A series of poly(methy1 methacrylate) formulations differing widely in chemical
and physical properties was employed for the evaluation of primary screening
methods for the assessment of acute toxicity. Materials and USP extracts of
materials were tested in parallel. Tissue culture, hemolysis, intradermal irritation,
systemic toxicity, muscle implant and histopathologic responses were
determined for each of 27 formulations. A determination of the nonvolatile
methanol extractable components was carried out on each formulation. The
formulations varied with respect to percent, w/w, methyl methacrylate, N,Ndimethyl-
p-toluidine, stannous octoate, 3,4-diamino-toluene and, also, with
respect to curing conditions. Volatile components, primarily methyl methacrylate,
of three selected formulations were determined quantitatively by vacuum
distillation and mass spectrographic analysis.
Statistical analysis of the primary data indicated a significant correlation of
residue weight (methanol extractable) with hemolytic activity (r = 0.93) and
with the cumulative biological response (r = 0.9). Multiple linear regression
analysis of residue weights with hemolysis and intradermal irriation responses
gave the highest overall correlation (r = 0.96). Hemolytic activity and tissue
culture responses were significantly correlated (r = 0.87). It was concluded
that the observed variation of biological test results reflected significant differences
in the toxicity of the test materials. The poly(methy1 methacrylate)
series examined was relatively low in toxicity and the biological tests examined,
particularly the in vitro tests, were found to be responsive to formulation and
curing conditions which indicated their suitability for primary toxicity screening.
Spectrophotometric Estimation of Drugs Using Potassium Permanganate and Saffr...iosrjce
IOSR Journal of Applied Chemistry (IOSR-JAC) is a double blind peer reviewed International Journal that provides rapid publication (within a month) of articles in all areas of applied chemistry and its applications. The journal welcomes publications of high quality papers on theoretical developments and practical applications in Chemical Science. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
This document reviews various sources of impurities that can arise during the development and manufacturing of drug products. It discusses impurities that originate from starting materials, solvents, intermediates, byproducts, formulation excipients, storage conditions, and processing methods. Specific examples of impurity types are provided, such as crystallization-related impurities, stereochemistry-related impurities, residual solvents, synthetic intermediates and byproducts, formulation-related impurities, degradation impurities from hydrolysis, oxidation and photolysis. The sources and formation of impurities are an important consideration in ensuring the quality, safety and efficacy of drug products.
Introduction,Drug- Excipient Compatibility Experimental Design ,Excipient role in drug destabilization,DRUG EXCIPIENT COMPATIBILTY IN PARENTERAL PRODUCTS.This topic are described.
This document provides guidance on preformulation studies for new drug substances. It outlines the key steps in preclinical testing including pharmacology, toxicology, and preformulation. Preformulation involves characterizing the physicochemical properties of the drug, including solubility, pKa, partition coefficient, stability, and crystal properties. The goal is to design an optimal drug delivery system through understanding the physical and chemical attributes of the new molecule.
Preformulation testing involves investigating a drug's physical and chemical properties alone and with excipients. This helps formulators develop stable and bioavailable dosage forms. Tests examine properties like solubility, stability, and purity which provide information on developing solid dosage forms. Understanding these properties is the first step in rational drug development.
This document discusses drug-excipient compatibility studies. It begins by explaining the importance of these studies in maximizing dosage form stability and avoiding formulation problems. It then describes the goals of compatibility studies and various mechanisms of drug-excipient interactions including physical, chemical, and physiological interactions. Finally, it outlines several analytical methods used in compatibility studies, including thermal techniques like DSC, spectroscopic techniques like vibrational spectroscopy, and chromatographic techniques like HPLC.
Combined effects of PEGylation and particle size on uptake of PLGA particles ...Nanomedicine Journal (NMJ)
Abstract
Objective:
At the present study, relationship between phagocytosis of PLGA particles and combined effects of particle size and surface PEGylation was investigated.
Materials and Methods:
Microspheres and nanospheres (3500 nm and 700 nm) were prepared from three types of PLGA polymers (non-PEGylated and PEGylation percents of 9% and 15%). These particles were prepared by solvent evaporation method. All particles were labeled with FITC-Albumin. Interaction of particles with J744.A.1 mouse macrophage cells, was evaluated in the absence or presence of 7% of the serum by flowcytometry method.
Results:
The study revealed more phagocytosis of nanospheres. In the presence of the serum, PEGylated particles were phagocytosed less than non-PEGylated particles. For nanospheres, this difference was significant (P<0/05) and their uptake was affected by PEGylation degree. In the case of microsphere formulation, PEGylation did not affect the cell uptake. In the serum-free medium, the bigger particles had more cell uptake rate than smaller ones but the cell uptake rate was not influenced by PEGylation.
Conclusion:
The results indicated that in nanosized particles both size and PEgylation degree could affect the phagocytosis, but in micron sized particles just size, and not the PEGylation degree, could affect this.
Spectrophotometric Estimation of Drugs Using Potassium Permanganate and Saffr...iosrjce
IOSR Journal of Applied Chemistry (IOSR-JAC) is a double blind peer reviewed International Journal that provides rapid publication (within a month) of articles in all areas of applied chemistry and its applications. The journal welcomes publications of high quality papers on theoretical developments and practical applications in Chemical Science. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
This document reviews various sources of impurities that can arise during the development and manufacturing of drug products. It discusses impurities that originate from starting materials, solvents, intermediates, byproducts, formulation excipients, storage conditions, and processing methods. Specific examples of impurity types are provided, such as crystallization-related impurities, stereochemistry-related impurities, residual solvents, synthetic intermediates and byproducts, formulation-related impurities, degradation impurities from hydrolysis, oxidation and photolysis. The sources and formation of impurities are an important consideration in ensuring the quality, safety and efficacy of drug products.
Introduction,Drug- Excipient Compatibility Experimental Design ,Excipient role in drug destabilization,DRUG EXCIPIENT COMPATIBILTY IN PARENTERAL PRODUCTS.This topic are described.
This document provides guidance on preformulation studies for new drug substances. It outlines the key steps in preclinical testing including pharmacology, toxicology, and preformulation. Preformulation involves characterizing the physicochemical properties of the drug, including solubility, pKa, partition coefficient, stability, and crystal properties. The goal is to design an optimal drug delivery system through understanding the physical and chemical attributes of the new molecule.
Preformulation testing involves investigating a drug's physical and chemical properties alone and with excipients. This helps formulators develop stable and bioavailable dosage forms. Tests examine properties like solubility, stability, and purity which provide information on developing solid dosage forms. Understanding these properties is the first step in rational drug development.
This document discusses drug-excipient compatibility studies. It begins by explaining the importance of these studies in maximizing dosage form stability and avoiding formulation problems. It then describes the goals of compatibility studies and various mechanisms of drug-excipient interactions including physical, chemical, and physiological interactions. Finally, it outlines several analytical methods used in compatibility studies, including thermal techniques like DSC, spectroscopic techniques like vibrational spectroscopy, and chromatographic techniques like HPLC.
Combined effects of PEGylation and particle size on uptake of PLGA particles ...Nanomedicine Journal (NMJ)
Abstract
Objective:
At the present study, relationship between phagocytosis of PLGA particles and combined effects of particle size and surface PEGylation was investigated.
Materials and Methods:
Microspheres and nanospheres (3500 nm and 700 nm) were prepared from three types of PLGA polymers (non-PEGylated and PEGylation percents of 9% and 15%). These particles were prepared by solvent evaporation method. All particles were labeled with FITC-Albumin. Interaction of particles with J744.A.1 mouse macrophage cells, was evaluated in the absence or presence of 7% of the serum by flowcytometry method.
Results:
The study revealed more phagocytosis of nanospheres. In the presence of the serum, PEGylated particles were phagocytosed less than non-PEGylated particles. For nanospheres, this difference was significant (P<0/05) and their uptake was affected by PEGylation degree. In the case of microsphere formulation, PEGylation did not affect the cell uptake. In the serum-free medium, the bigger particles had more cell uptake rate than smaller ones but the cell uptake rate was not influenced by PEGylation.
Conclusion:
The results indicated that in nanosized particles both size and PEgylation degree could affect the phagocytosis, but in micron sized particles just size, and not the PEGylation degree, could affect this.
Interaction of drug with excipient residuesMeghana Gowda
Excipients are not perfectly pure and may contain low levels of residues and impurities that can interact with drug substances. Common excipient residues include peroxides, aldehydes, reducing sugars, and antioxidants. Interactions between drug and excipient residues can accelerate drug degradation through processes like oxidation, hydrolysis, and Maillard reactions. Vigilance is needed to avoid interactions that compromise product quality, performance, or safety, especially for biopharmaceutical products where even minor interactions could damage protein structures. Information on potentially degrading excipient residues is often lacking but could help avoid undesirable interactions during product development.
Preformulation part 1- Preformulation- Crystal, Amorphous, Polymorphism, Pseu...vijaysrampur
The document provides an introduction to preformulation, which involves studying the physical and chemical properties of a drug substance prior to formulation development. The goals of preformulation are to generate information to develop stable, bioavailable dosage forms and establish parameters that may affect drug performance. Key physical properties studied include organoleptic characteristics, bulk properties like solubility and polymorphism, and chemical properties like hydrolysis and oxidation. Understanding these characteristics is essential for designing optimal drug delivery systems. Preformulation is the first step in rational development of a dosage form.
This document discusses key considerations for dosage form design and formulation. It outlines the need to consider the physical and chemical properties of drug substances and ensure compatibility between ingredients. Preformulation studies are important to characterize drug properties like solubility, dissolution rate, and stability. These studies help determine the appropriate dosage form and ensure the drug is delivered effectively and safely. The goals of a proper design are to provide patient benefit while protecting drug integrity throughout production, storage, and use.
The impurities in pharmaceuticals are unwanted chemicals that remain with the active pharmaceutical ingredients
(APIs) or develop during formulation or upon aging of both API and formulation.
Preformulation studies investigate the physical, chemical, and mechanical properties of a new drug substance. This is done to develop a safe, effective, and stable dosage form and is an integral part of drug development. The main goals of preformulation studies are to establish the drug's physicochemical properties, determine its kinetic profile and stability, determine compatibility with excipients, and know appropriate processing and storage methods. To achieve these goals, preformulation studies examine parameters like the drug's organoleptic properties, bulk characters, solubility, and stability. This provides essential information to formulate the drug into a dosage form that can be safely administered.
Impact of Steam and Gamma Processing on Extractableijsrd.com
In Pharma application various elastomeric components are used as primary packaging and fluid transportation. Several methods are available for sterilization and among all steam & gamma sterilization are most suitable methods for elastomeric components. In this study the effect of steam & gamma sterilization has been compared with non sterile components. Steam and gamma which has been used as a source for sterilization that may affect the molecular chain & crosslink density of elastomeric components. This study serves to help understand the potential deterioration of physical and chemical properties, the possible impact to functionality and the potential changes to the extractable/leachable profile as a result of sterilization.
The document discusses drug-excipient interactions, which can occur through physical, chemical, or biopharmaceutical mechanisms. Excipients are inactive ingredients that are formulated alongside drugs, and ideal excipients are pharmacologically inert and do not interact with the drug. Drug-excipient interactions can decrease drug stability and bioavailability if they lead to the formation of insoluble complexes, chemical degradation, or influence drug absorption. It is important to study drug-excipient compatibility to maximize dosage form stability and ensure safety. Analytical techniques like DSC, TLC, and HPLC can be used to detect these interactions.
This document summarizes research on immobilizing the enzyme laccase in an alginate-gelatin mixed gel and using it to decolorize synthetic dyes like crystal violet. Key findings include:
1) Spherical beads were formed using various alginate concentrations, with 5% alginate beads having the highest mechanical stability.
2) Both free and immobilized laccase worked best at pH 8-9 and 50°C for crystal violet decolorization.
3) The immobilized laccase retained 85% activity after 5 reuse cycles and effectively decolorized various dyes like amido black and malachite green.
This document describes the synthesis and properties of a new urea-formaldehyde (UF) resin modified with hydroxymethyl furfural (HMF). HMF was introduced to replace some of the formaldehyde in order to improve thermal stability, reduce formaldehyde emissions, and utilize a bio-based monomer. UF and urea-HMF-formaldehyde (UHF) resins were synthesized using an alkaline-acid method and characterized. Particleboards made with UHF resin showed improved mechanical properties, lower water absorption and thickness swelling, and reduced formaldehyde emissions compared to UF resin particleboards. The UHF resin demonstrated potential as an alternative adhesive for wood panels with benefits over traditional UF resin.
Excipients play an important role in drug formulations by acting as bulking agents, protective agents, and improving drug bioavailability. Excipients can interact with active pharmaceutical ingredients through physical, chemical, and biopharmaceutical interactions. These interactions can affect properties like drug stability, release, and absorption. It is important to select excipients that do not interact with drugs and understand how excipients may influence drug performance and safety after administration.
This document discusses excipients and their interactions with active pharmaceutical ingredients. It begins by defining excipients as inactive substances that are formulated alongside active ingredients for purposes such as bulking up medications. Excipients can affect properties like drug release, bioavailability, stability, and ease of administration. The document then examines ideal excipient properties and classifications. It proceeds to discuss four types of drug-excipient interactions: physical interactions which do not involve chemical changes; chemical interactions where ingredients react to form new compounds; biopharmaceutical interactions affecting absorption; and excipient-excipient interactions which can be undesirable or advantageous. Specific examples are provided to illustrate each type of interaction.
Spectroscopic-Based Chemometric Models for Quantifying Low Levels of Solid-St...Dhaval shah
This document describes the development and validation of chemometric models using Raman and near infrared spectroscopy (NIR) to quantify low levels (less than 5% of total content) of solid-state transitions between theophylline anhydrous form II (THA) and theophylline monohydrate (TMO) in extended release theophylline formulations. Calibration samples containing mixtures of THA and TMO formulations from 0-25% TMO were used to develop partial least squares and principal component regression models after pretreating the spectroscopic data with scatter removal and derivatization techniques. The models were assessed based on diagnostic statistics and shown to have good fit and performance for quantifying TMO content, demonstrating their potential
This research article investigates the bioactivity of the ethanolic leaf extract of Boehmeria macrophylla (BMET). Phytochemical screening revealed the presence of various compounds including alkaloids, tannins, and flavonoids in BMET. In vitro assays found the extract exhibited antioxidant, analgesic, cytotoxic, and antibacterial activities. Specifically, BMET showed free radical scavenging activity in the DPPH assay with an IC50 value of 39.76 μg/mL, comparable to ascorbic acid. In mice, BMET demonstrated 32.91% and 54.2% reductions in acetic acid-induced writhing at doses of 250 and 500 mg/kg, respectively. In br
Degradation of poly-L-lactide. Part 1, IMechE, 2004Dr Neill Weir
The document summarizes a study that evaluated the in vitro and in vivo degradation of poly-L-lactide (PLLA) over time. PLLA samples were processed into rods and tensile specimens, sterilized, and degraded in both physiological buffer solution and implanted subcutaneously in rats. Properties like molecular weight, crystallinity, mechanical strength, and thermal properties were evaluated at various time points. The results showed degradation proceeded at the same rate in both environments, suggesting enzymes did not accelerate degradation in vivo. Additionally, the lack of inflammatory response indicated good biocompatibility of PLLA over the 44-week study period before mass loss was observed.
Preformulation is the stage of development where the physicochemical properties of a drug substance are characterized and established. The objectives of preformulation study are to develop an elegant, stable, effective and safe dosage form by establishing the kinetic rate profile, compatibility with other ingredients, and physicochemical parameters of new drug substances. The physicochemical properties of a drug, such as its ability to elicit a pharmacological effect, are related to how those properties influence the biomolecule it interacts with.
This document provides an overview of preformulation studies for developing drug formulations. It discusses the importance of studying the physical and chemical properties of drug substances alone and when combined with excipients. The summary is:
1) Preformulation studies investigate the physical and chemical properties of drugs and how they interact with excipients. This helps formulators develop stable, bioavailable drug products.
2) Key properties studied include solubility, particle size, solid state properties, and how the drug behaves under different conditions like temperature, light and pH.
3) The results of preformulation studies guide formulation development and ensure the final product has the desired quality, performance and safety.
Physico chemical nature of drug, 1.Crystallinity:Amorphous
Effects of flow property
It affects compaction
Important in aerosol.
Effects chemical stability
This document summarizes a research article about the biocompatibility of resin-modified filling materials. It discusses how resin-based dental materials release components like monomers into the oral environment that can cause local and systemic adverse effects. The article reviews methods used to evaluate the cytotoxicity and biological effects of these materials, including cell culture experiments and standardized tests. It concludes that more research is needed to understand the interactions between resin components and tissues and the potential clinical consequences.
This document summarizes the development and evaluation of an in situ gelling system for the treatment of periodontitis using tinidazole as the model drug. Tinidazole was incorporated into gellan gum and poloxamer 407 polymer matrices using a 32 full factorial design to optimize the formulation variables. Nine formulations were developed varying the concentration of gellan gum (0.5-1.5% w/v) and poloxamer 407 (10-20% w/v). The formulations were characterized for appearance, gelling capacity, pH, viscosity, gelation temperature, drug content, syringeability and in vitro drug release. The optimized formulation with maximum desirability contained 0.5% w/
Interaction of drug with excipient residuesMeghana Gowda
Excipients are not perfectly pure and may contain low levels of residues and impurities that can interact with drug substances. Common excipient residues include peroxides, aldehydes, reducing sugars, and antioxidants. Interactions between drug and excipient residues can accelerate drug degradation through processes like oxidation, hydrolysis, and Maillard reactions. Vigilance is needed to avoid interactions that compromise product quality, performance, or safety, especially for biopharmaceutical products where even minor interactions could damage protein structures. Information on potentially degrading excipient residues is often lacking but could help avoid undesirable interactions during product development.
Preformulation part 1- Preformulation- Crystal, Amorphous, Polymorphism, Pseu...vijaysrampur
The document provides an introduction to preformulation, which involves studying the physical and chemical properties of a drug substance prior to formulation development. The goals of preformulation are to generate information to develop stable, bioavailable dosage forms and establish parameters that may affect drug performance. Key physical properties studied include organoleptic characteristics, bulk properties like solubility and polymorphism, and chemical properties like hydrolysis and oxidation. Understanding these characteristics is essential for designing optimal drug delivery systems. Preformulation is the first step in rational development of a dosage form.
This document discusses key considerations for dosage form design and formulation. It outlines the need to consider the physical and chemical properties of drug substances and ensure compatibility between ingredients. Preformulation studies are important to characterize drug properties like solubility, dissolution rate, and stability. These studies help determine the appropriate dosage form and ensure the drug is delivered effectively and safely. The goals of a proper design are to provide patient benefit while protecting drug integrity throughout production, storage, and use.
The impurities in pharmaceuticals are unwanted chemicals that remain with the active pharmaceutical ingredients
(APIs) or develop during formulation or upon aging of both API and formulation.
Preformulation studies investigate the physical, chemical, and mechanical properties of a new drug substance. This is done to develop a safe, effective, and stable dosage form and is an integral part of drug development. The main goals of preformulation studies are to establish the drug's physicochemical properties, determine its kinetic profile and stability, determine compatibility with excipients, and know appropriate processing and storage methods. To achieve these goals, preformulation studies examine parameters like the drug's organoleptic properties, bulk characters, solubility, and stability. This provides essential information to formulate the drug into a dosage form that can be safely administered.
Impact of Steam and Gamma Processing on Extractableijsrd.com
In Pharma application various elastomeric components are used as primary packaging and fluid transportation. Several methods are available for sterilization and among all steam & gamma sterilization are most suitable methods for elastomeric components. In this study the effect of steam & gamma sterilization has been compared with non sterile components. Steam and gamma which has been used as a source for sterilization that may affect the molecular chain & crosslink density of elastomeric components. This study serves to help understand the potential deterioration of physical and chemical properties, the possible impact to functionality and the potential changes to the extractable/leachable profile as a result of sterilization.
The document discusses drug-excipient interactions, which can occur through physical, chemical, or biopharmaceutical mechanisms. Excipients are inactive ingredients that are formulated alongside drugs, and ideal excipients are pharmacologically inert and do not interact with the drug. Drug-excipient interactions can decrease drug stability and bioavailability if they lead to the formation of insoluble complexes, chemical degradation, or influence drug absorption. It is important to study drug-excipient compatibility to maximize dosage form stability and ensure safety. Analytical techniques like DSC, TLC, and HPLC can be used to detect these interactions.
This document summarizes research on immobilizing the enzyme laccase in an alginate-gelatin mixed gel and using it to decolorize synthetic dyes like crystal violet. Key findings include:
1) Spherical beads were formed using various alginate concentrations, with 5% alginate beads having the highest mechanical stability.
2) Both free and immobilized laccase worked best at pH 8-9 and 50°C for crystal violet decolorization.
3) The immobilized laccase retained 85% activity after 5 reuse cycles and effectively decolorized various dyes like amido black and malachite green.
This document describes the synthesis and properties of a new urea-formaldehyde (UF) resin modified with hydroxymethyl furfural (HMF). HMF was introduced to replace some of the formaldehyde in order to improve thermal stability, reduce formaldehyde emissions, and utilize a bio-based monomer. UF and urea-HMF-formaldehyde (UHF) resins were synthesized using an alkaline-acid method and characterized. Particleboards made with UHF resin showed improved mechanical properties, lower water absorption and thickness swelling, and reduced formaldehyde emissions compared to UF resin particleboards. The UHF resin demonstrated potential as an alternative adhesive for wood panels with benefits over traditional UF resin.
Excipients play an important role in drug formulations by acting as bulking agents, protective agents, and improving drug bioavailability. Excipients can interact with active pharmaceutical ingredients through physical, chemical, and biopharmaceutical interactions. These interactions can affect properties like drug stability, release, and absorption. It is important to select excipients that do not interact with drugs and understand how excipients may influence drug performance and safety after administration.
This document discusses excipients and their interactions with active pharmaceutical ingredients. It begins by defining excipients as inactive substances that are formulated alongside active ingredients for purposes such as bulking up medications. Excipients can affect properties like drug release, bioavailability, stability, and ease of administration. The document then examines ideal excipient properties and classifications. It proceeds to discuss four types of drug-excipient interactions: physical interactions which do not involve chemical changes; chemical interactions where ingredients react to form new compounds; biopharmaceutical interactions affecting absorption; and excipient-excipient interactions which can be undesirable or advantageous. Specific examples are provided to illustrate each type of interaction.
Spectroscopic-Based Chemometric Models for Quantifying Low Levels of Solid-St...Dhaval shah
This document describes the development and validation of chemometric models using Raman and near infrared spectroscopy (NIR) to quantify low levels (less than 5% of total content) of solid-state transitions between theophylline anhydrous form II (THA) and theophylline monohydrate (TMO) in extended release theophylline formulations. Calibration samples containing mixtures of THA and TMO formulations from 0-25% TMO were used to develop partial least squares and principal component regression models after pretreating the spectroscopic data with scatter removal and derivatization techniques. The models were assessed based on diagnostic statistics and shown to have good fit and performance for quantifying TMO content, demonstrating their potential
This research article investigates the bioactivity of the ethanolic leaf extract of Boehmeria macrophylla (BMET). Phytochemical screening revealed the presence of various compounds including alkaloids, tannins, and flavonoids in BMET. In vitro assays found the extract exhibited antioxidant, analgesic, cytotoxic, and antibacterial activities. Specifically, BMET showed free radical scavenging activity in the DPPH assay with an IC50 value of 39.76 μg/mL, comparable to ascorbic acid. In mice, BMET demonstrated 32.91% and 54.2% reductions in acetic acid-induced writhing at doses of 250 and 500 mg/kg, respectively. In br
Degradation of poly-L-lactide. Part 1, IMechE, 2004Dr Neill Weir
The document summarizes a study that evaluated the in vitro and in vivo degradation of poly-L-lactide (PLLA) over time. PLLA samples were processed into rods and tensile specimens, sterilized, and degraded in both physiological buffer solution and implanted subcutaneously in rats. Properties like molecular weight, crystallinity, mechanical strength, and thermal properties were evaluated at various time points. The results showed degradation proceeded at the same rate in both environments, suggesting enzymes did not accelerate degradation in vivo. Additionally, the lack of inflammatory response indicated good biocompatibility of PLLA over the 44-week study period before mass loss was observed.
Preformulation is the stage of development where the physicochemical properties of a drug substance are characterized and established. The objectives of preformulation study are to develop an elegant, stable, effective and safe dosage form by establishing the kinetic rate profile, compatibility with other ingredients, and physicochemical parameters of new drug substances. The physicochemical properties of a drug, such as its ability to elicit a pharmacological effect, are related to how those properties influence the biomolecule it interacts with.
This document provides an overview of preformulation studies for developing drug formulations. It discusses the importance of studying the physical and chemical properties of drug substances alone and when combined with excipients. The summary is:
1) Preformulation studies investigate the physical and chemical properties of drugs and how they interact with excipients. This helps formulators develop stable, bioavailable drug products.
2) Key properties studied include solubility, particle size, solid state properties, and how the drug behaves under different conditions like temperature, light and pH.
3) The results of preformulation studies guide formulation development and ensure the final product has the desired quality, performance and safety.
Physico chemical nature of drug, 1.Crystallinity:Amorphous
Effects of flow property
It affects compaction
Important in aerosol.
Effects chemical stability
This document summarizes a research article about the biocompatibility of resin-modified filling materials. It discusses how resin-based dental materials release components like monomers into the oral environment that can cause local and systemic adverse effects. The article reviews methods used to evaluate the cytotoxicity and biological effects of these materials, including cell culture experiments and standardized tests. It concludes that more research is needed to understand the interactions between resin components and tissues and the potential clinical consequences.
This document summarizes the development and evaluation of an in situ gelling system for the treatment of periodontitis using tinidazole as the model drug. Tinidazole was incorporated into gellan gum and poloxamer 407 polymer matrices using a 32 full factorial design to optimize the formulation variables. Nine formulations were developed varying the concentration of gellan gum (0.5-1.5% w/v) and poloxamer 407 (10-20% w/v). The formulations were characterized for appearance, gelling capacity, pH, viscosity, gelation temperature, drug content, syringeability and in vitro drug release. The optimized formulation with maximum desirability contained 0.5% w/
FORMULATION AND INVITRO EVALUATION OF COLON SPECIFIC DRUG DELIVERY SYSTEM BY ...alok prakash kar
The document describes the formulation and in vitro evaluation of a colon-specific drug delivery system containing metronidazole. Metronidazole tablets were prepared using different polymers like ethyl cellulose, cellulose acetate butyrate, and Eudragit polymers. The tablets were then coated with various polymer coating suspensions. The coated tablets were evaluated for film thickness, weight gain, hardness, disintegration time, and drug release. The results showed that the coating thickness and weight gain increased with increasing polymer concentration in the coating suspension. The coated tablets had suitable hardness and disintegration times while sustaining drug release in the acidic environment of the stomach.
This document summarizes ongoing research into the development of an aliphatic polycarbonate polymer vector for targeted gene therapy delivery. The polymer is synthesized via ring-opening polymerization of cyclic monomers using a non-toxic catalyst, resulting in polymers that are biocompatible, biodegradable, and exhibit controlled molecular weight and low polydispersity. Future work includes adding a clickable group to allow fixation of muscle cell-targeting agents, then evaluating cytotoxicity and transfection efficiency of the targeted nanoparticles. The goal is a safe and effective synthetic polymer system for delivery of antisense oligonucleotides to treat neuromuscular disorders.
This document describes chemical surface modification of poly(ethylene terephthalate) (PET) fibers through aminolysis and grafting of carbohydrates. PET fibers were treated with diamines to introduce amino groups on the surface via aminolysis. Various diamines, temperatures, times and concentrations were tested to optimize the reaction. Amino-functionalized PET fibers were then used to graft carbohydrates like maltose, maltotriose and maltohexaose via reductive amination or amidation. The grafting yield depended on the initial amino group concentration and carbohydrate molecular weight. Sugar-coated PET fibers could have applications in biomedical areas.
This document examines the thermal stability, antioxidant activity, and photo-oxidation of natural polyphenols. Specifically, it investigates standard polyphenol solutions (catechin, gallic acid, vanillic acid) and vegetal extracts from spruce bark and grape seeds. The key findings are:
1) Polyphenols showed relative thermal stability when exposed to temperatures from 60-100°C, with degradations ranging from 15-30% after 4 hours.
2) Gallic acid and catechin exhibited the highest antioxidant activity based on DPPH radical scavenging assays.
3) UV exposure caused significant degradation of polyphenols, removing around 40% of vanillic acid, 50%
Xenobiotics are compounds foreign to the body that are metabolized. They can affect many body systems like the immune, neurological, and endocrine systems and cause issues like immune dysfunction, cancer, and reproductive problems. Common sources include the petrochemical, plastic, pesticide, paint, and electronic industries. Xenobiotics are metabolized through oxidation, reduction, hydrolysis, and conjugation reactions involving enzymes like cytochrome P450 and uridine diphosphate glucuronosyltransferases. This metabolism can produce toxic intermediates like epoxides that bind to DNA. Fluoride is a toxic substance added to food and water that accumulates in bones and the pineal gland, and may be
Impact of formulation and process variables on solid-state stability of theop...Dhaval shah
This study investigated the impact of formulation and processing variables on the solid-state stability of theophylline in controlled-release formulations over 3 months of storage. Twelve formulations were prepared using a full factorial design to examine the effects of polymer type, diluent, granulation method (wet vs. dry), and granulation fluid (water vs. isopropanol) on the transition of anhydrous theophylline to the monohydrate form. Physicochemical analysis revealed a decrease in tablet hardness and increase in moisture content for all wet-granulated formulations, which underwent a solid-state transition to the monohydrate, compared to no transition in dry-compressed or isopropanol granulated formulations. The transition decreased
folic acid chitosan conjugate nanoparticle containing azithromycin for the tr...shivamgupta1083
The document presents a research proposal for developing folic acid-chitosan conjugate nanoparticles containing azithromycin for treating colorectal diseases. The objectives are to prepare drug-loaded conjugates with desired release characteristics and assess their targeting efficacy and bio-distribution. The plan involves preformulation studies, preparing the folic acid-chitosan conjugate, loading the conjugate with azithromycin, and characterizing the nanoparticles. In vitro and in vivo studies will evaluate particle properties, drug release, cytotoxicity, and the ability to treat colorectal inflammation in a rat model.
The document discusses preformulation of sterile products. It covers key areas of preformulation including bulk characterization, solubility analysis, and stability analysis. Bulk characterization involves assessing properties like crystallinity, polymorphism, particle size, powder flow, and hygroscopicity. Solubility analysis includes studying aqueous solubility, drug ionization at physiological pH, partition coefficient, and thermal effects. Stability analysis focuses on stability in toxicology formulations, solution stability, and solid state stability under various conditions. The goal of preformulation is to characterize important physicochemical properties of drug substances to aid in developing appropriate formulations.
Research by Mahendra Kumar Trivedi - Physical, Thermal and Spectroscopic Char...john henrry
Research on Trivedi Effect - The aim of present study was to evaluate the impact of Biofield treatment on physical, thermal and spectroscopic properties of MTA. MTA sample was divided into two groups that served as treated and control. The treated group received Mr. Mahendra Kumar Trivedi’s Biofield treatment.to read nmore visit http://www.academicroom.com/article/physical-thermal-and-spectroscopic-characterization-m-toluic-acid-impact-biofield-treatment-0
The document discusses key differences between biotherapeutics (large molecule medicines produced from living cells) and small molecule medicines. Biotherapeutics are much larger and more complex structures than small molecules. Their development, manufacturing, and regulatory evaluation require specialized considerations and standards due to their sensitivity, potential for immunogenicity, and structural complexity. The document outlines the complex manufacturing processes required for biotherapeutics, regulatory frameworks for evaluating manufacturing changes and ensuring comparability over the product lifecycle, and calls for dedicated legislation and guidance to appropriately regulate biotherapeutic development, approval, and post-marketing activities.
Biocompatibility of Polymethylmethacrylate resinsHashmat Gul
This document provides a summary of the biocompatibility of polymethylmethacrylate (PMMA) resins. It discusses the various uses of PMMA in dentistry and daily life. It then examines the composition of PMMA resins and how they are classified. The document analyzes the release of substances from PMMA resins like residual monomers, formaldehyde, and other components. It also evaluates the systemic and local toxicity of PMMA as well as its tissue compatibility, microbial effects, implantation studies, reactions in pulp and oral tissues, and potential to cause allergies.
it provide a brief note on the drug excipient interaction and various technique to find it which is a part of preformulation studies. it gives help to mpharm(pharmaceutics) students. i.
The document summarizes research into developing tamoxifen citrate-loaded nanoparticles using the biodegradable polymer PLGA for breast cancer treatment. PLGA nanoparticles containing tamoxifen citrate were prepared using emulsion solvent evaporation techniques. Process parameters like drug-polymer ratio and homogenization speed were optimized. Characterization studies showed the nanoparticles were spherical and smooth. In vitro drug release was evaluated over time, with release profiles varying by centrifugation speed. Drug loading efficiency ranged from 18.6-71.98%. The nanoparticles showed potential as a controlled drug delivery system for tamoxifen citrate.
1.preformulation concept in Modern pharmaceutics.pptxPNMallikarjun
Preformulation is defined as the investigation of physical and chemical properties of a drug substance alone and when combined with excipients. The goal is to generate information to help formulators develop stable and safe dosage forms with good bioavailability. Some key tests include determining the drug's solubility, stability, and compatibility with various excipients using techniques like DSC, TLC, and HPLC. This provides critical data to guide the rational selection of dosage form and formulation components.
Formulation and evaluation of folding film in a capsule for gastroretentive d...Bashant Kumar sah
This document describes research into developing a gastroretentive drug delivery system for losartan potassium using folding films enclosed in capsules. Sustained release films were prepared using polymers like HPMC and ethyl cellulose with polyethylene glycol as a plasticizer, through a solvent casting method. The films were evaluated for parameters like weight variation, thickness, folding endurance, tensile strength, drug content uniformity, surface pH and dissolution. A 2^3 factorial design was used to optimize the formulations, evaluating the effects of polymer amount, plasticizer amount, and coating solution concentration on drug release. The optimized formulations showed sustained drug release and remained stable over 30 days in accelerated stability studies.
This document discusses drug-excipient interactions. It begins by introducing excipients and their important roles in drug formulations. It then describes common types of excipients and outlines four main types of drug-excipient interactions: physical, chemical, biopharmaceutical, and excipient-excipient. Several analytical techniques for detecting interactions are also discussed, including thermal methods like DSC and DTA, spectroscopy like FT-IR, and chromatography like TLC and HPLC. The document emphasizes the importance of studying drug-excipient compatibility to ensure formulation stability and safety.
Similar to Dillingham1975.biological evaluation of polymers (20)
Using recycled concrete aggregates (RCA) for pavements is crucial to achieving sustainability. Implementing RCA for new pavement can minimize carbon footprint, conserve natural resources, reduce harmful emissions, and lower life cycle costs. Compared to natural aggregate (NA), RCA pavement has fewer comprehensive studies and sustainability assessments.
Embedded machine learning-based road conditions and driving behavior monitoringIJECEIAES
Car accident rates have increased in recent years, resulting in losses in human lives, properties, and other financial costs. An embedded machine learning-based system is developed to address this critical issue. The system can monitor road conditions, detect driving patterns, and identify aggressive driving behaviors. The system is based on neural networks trained on a comprehensive dataset of driving events, driving styles, and road conditions. The system effectively detects potential risks and helps mitigate the frequency and impact of accidents. The primary goal is to ensure the safety of drivers and vehicles. Collecting data involved gathering information on three key road events: normal street and normal drive, speed bumps, circular yellow speed bumps, and three aggressive driving actions: sudden start, sudden stop, and sudden entry. The gathered data is processed and analyzed using a machine learning system designed for limited power and memory devices. The developed system resulted in 91.9% accuracy, 93.6% precision, and 92% recall. The achieved inference time on an Arduino Nano 33 BLE Sense with a 32-bit CPU running at 64 MHz is 34 ms and requires 2.6 kB peak RAM and 139.9 kB program flash memory, making it suitable for resource-constrained embedded systems.
CHINA’S GEO-ECONOMIC OUTREACH IN CENTRAL ASIAN COUNTRIES AND FUTURE PROSPECTjpsjournal1
The rivalry between prominent international actors for dominance over Central Asia's hydrocarbon
reserves and the ancient silk trade route, along with China's diplomatic endeavours in the area, has been
referred to as the "New Great Game." This research centres on the power struggle, considering
geopolitical, geostrategic, and geoeconomic variables. Topics including trade, political hegemony, oil
politics, and conventional and nontraditional security are all explored and explained by the researcher.
Using Mackinder's Heartland, Spykman Rimland, and Hegemonic Stability theories, examines China's role
in Central Asia. This study adheres to the empirical epistemological method and has taken care of
objectivity. This study analyze primary and secondary research documents critically to elaborate role of
china’s geo economic outreach in central Asian countries and its future prospect. China is thriving in trade,
pipeline politics, and winning states, according to this study, thanks to important instruments like the
Shanghai Cooperation Organisation and the Belt and Road Economic Initiative. According to this study,
China is seeing significant success in commerce, pipeline politics, and gaining influence on other
governments. This success may be attributed to the effective utilisation of key tools such as the Shanghai
Cooperation Organisation and the Belt and Road Economic Initiative.
Introduction- e - waste – definition - sources of e-waste– hazardous substances in e-waste - effects of e-waste on environment and human health- need for e-waste management– e-waste handling rules - waste minimization techniques for managing e-waste – recycling of e-waste - disposal treatment methods of e- waste – mechanism of extraction of precious metal from leaching solution-global Scenario of E-waste – E-waste in India- case studies.
TIME DIVISION MULTIPLEXING TECHNIQUE FOR COMMUNICATION SYSTEMHODECEDSIET
Time Division Multiplexing (TDM) is a method of transmitting multiple signals over a single communication channel by dividing the signal into many segments, each having a very short duration of time. These time slots are then allocated to different data streams, allowing multiple signals to share the same transmission medium efficiently. TDM is widely used in telecommunications and data communication systems.
### How TDM Works
1. **Time Slots Allocation**: The core principle of TDM is to assign distinct time slots to each signal. During each time slot, the respective signal is transmitted, and then the process repeats cyclically. For example, if there are four signals to be transmitted, the TDM cycle will divide time into four slots, each assigned to one signal.
2. **Synchronization**: Synchronization is crucial in TDM systems to ensure that the signals are correctly aligned with their respective time slots. Both the transmitter and receiver must be synchronized to avoid any overlap or loss of data. This synchronization is typically maintained by a clock signal that ensures time slots are accurately aligned.
3. **Frame Structure**: TDM data is organized into frames, where each frame consists of a set of time slots. Each frame is repeated at regular intervals, ensuring continuous transmission of data streams. The frame structure helps in managing the data streams and maintaining the synchronization between the transmitter and receiver.
4. **Multiplexer and Demultiplexer**: At the transmitting end, a multiplexer combines multiple input signals into a single composite signal by assigning each signal to a specific time slot. At the receiving end, a demultiplexer separates the composite signal back into individual signals based on their respective time slots.
### Types of TDM
1. **Synchronous TDM**: In synchronous TDM, time slots are pre-assigned to each signal, regardless of whether the signal has data to transmit or not. This can lead to inefficiencies if some time slots remain empty due to the absence of data.
2. **Asynchronous TDM (or Statistical TDM)**: Asynchronous TDM addresses the inefficiencies of synchronous TDM by allocating time slots dynamically based on the presence of data. Time slots are assigned only when there is data to transmit, which optimizes the use of the communication channel.
### Applications of TDM
- **Telecommunications**: TDM is extensively used in telecommunication systems, such as in T1 and E1 lines, where multiple telephone calls are transmitted over a single line by assigning each call to a specific time slot.
- **Digital Audio and Video Broadcasting**: TDM is used in broadcasting systems to transmit multiple audio or video streams over a single channel, ensuring efficient use of bandwidth.
- **Computer Networks**: TDM is used in network protocols and systems to manage the transmission of data from multiple sources over a single network medium.
### Advantages of TDM
- **Efficient Use of Bandwidth**: TDM all
Using recycled concrete aggregates (RCA) for pavements is crucial to achieving sustainability. Implementing RCA for new pavement can minimize carbon footprint, conserve natural resources, reduce harmful emissions, and lower life cycle costs. Compared to natural aggregate (NA), RCA pavement has fewer comprehensive studies and sustainability assessments.
Harnessing WebAssembly for Real-time Stateless Streaming PipelinesChristina Lin
Traditionally, dealing with real-time data pipelines has involved significant overhead, even for straightforward tasks like data transformation or masking. However, in this talk, we’ll venture into the dynamic realm of WebAssembly (WASM) and discover how it can revolutionize the creation of stateless streaming pipelines within a Kafka (Redpanda) broker. These pipelines are adept at managing low-latency, high-data-volume scenarios.
A SYSTEMATIC RISK ASSESSMENT APPROACH FOR SECURING THE SMART IRRIGATION SYSTEMSIJNSA Journal
The smart irrigation system represents an innovative approach to optimize water usage in agricultural and landscaping practices. The integration of cutting-edge technologies, including sensors, actuators, and data analysis, empowers this system to provide accurate monitoring and control of irrigation processes by leveraging real-time environmental conditions. The main objective of a smart irrigation system is to optimize water efficiency, minimize expenses, and foster the adoption of sustainable water management methods. This paper conducts a systematic risk assessment by exploring the key components/assets and their functionalities in the smart irrigation system. The crucial role of sensors in gathering data on soil moisture, weather patterns, and plant well-being is emphasized in this system. These sensors enable intelligent decision-making in irrigation scheduling and water distribution, leading to enhanced water efficiency and sustainable water management practices. Actuators enable automated control of irrigation devices, ensuring precise and targeted water delivery to plants. Additionally, the paper addresses the potential threat and vulnerabilities associated with smart irrigation systems. It discusses limitations of the system, such as power constraints and computational capabilities, and calculates the potential security risks. The paper suggests possible risk treatment methods for effective secure system operation. In conclusion, the paper emphasizes the significant benefits of implementing smart irrigation systems, including improved water conservation, increased crop yield, and reduced environmental impact. Additionally, based on the security analysis conducted, the paper recommends the implementation of countermeasures and security approaches to address vulnerabilities and ensure the integrity and reliability of the system. By incorporating these measures, smart irrigation technology can revolutionize water management practices in agriculture, promoting sustainability, resource efficiency, and safeguarding against potential security threats.
Batteries -Introduction – Types of Batteries – discharging and charging of battery - characteristics of battery –battery rating- various tests on battery- – Primary battery: silver button cell- Secondary battery :Ni-Cd battery-modern battery: lithium ion battery-maintenance of batteries-choices of batteries for electric vehicle applications.
Fuel Cells: Introduction- importance and classification of fuel cells - description, principle, components, applications of fuel cells: H2-O2 fuel cell, alkaline fuel cell, molten carbonate fuel cell and direct methanol fuel cells.
Understanding Inductive Bias in Machine LearningSUTEJAS
This presentation explores the concept of inductive bias in machine learning. It explains how algorithms come with built-in assumptions and preferences that guide the learning process. You'll learn about the different types of inductive bias and how they can impact the performance and generalizability of machine learning models.
The presentation also covers the positive and negative aspects of inductive bias, along with strategies for mitigating potential drawbacks. We'll explore examples of how bias manifests in algorithms like neural networks and decision trees.
By understanding inductive bias, you can gain valuable insights into how machine learning models work and make informed decisions when building and deploying them.
DEEP LEARNING FOR SMART GRID INTRUSION DETECTION: A HYBRID CNN-LSTM-BASED MODELgerogepatton
As digital technology becomes more deeply embedded in power systems, protecting the communication
networks of Smart Grids (SG) has emerged as a critical concern. Distributed Network Protocol 3 (DNP3)
represents a multi-tiered application layer protocol extensively utilized in Supervisory Control and Data
Acquisition (SCADA)-based smart grids to facilitate real-time data gathering and control functionalities.
Robust Intrusion Detection Systems (IDS) are necessary for early threat detection and mitigation because
of the interconnection of these networks, which makes them vulnerable to a variety of cyberattacks. To
solve this issue, this paper develops a hybrid Deep Learning (DL) model specifically designed for intrusion
detection in smart grids. The proposed approach is a combination of the Convolutional Neural Network
(CNN) and the Long-Short-Term Memory algorithms (LSTM). We employed a recent intrusion detection
dataset (DNP3), which focuses on unauthorized commands and Denial of Service (DoS) cyberattacks, to
train and test our model. The results of our experiments show that our CNN-LSTM method is much better
at finding smart grid intrusions than other deep learning algorithms used for classification. In addition,
our proposed approach improves accuracy, precision, recall, and F1 score, achieving a high detection
accuracy rate of 99.50%.
Comparative analysis between traditional aquaponics and reconstructed aquapon...bijceesjournal
The aquaponic system of planting is a method that does not require soil usage. It is a method that only needs water, fish, lava rocks (a substitute for soil), and plants. Aquaponic systems are sustainable and environmentally friendly. Its use not only helps to plant in small spaces but also helps reduce artificial chemical use and minimizes excess water use, as aquaponics consumes 90% less water than soil-based gardening. The study applied a descriptive and experimental design to assess and compare conventional and reconstructed aquaponic methods for reproducing tomatoes. The researchers created an observation checklist to determine the significant factors of the study. The study aims to determine the significant difference between traditional aquaponics and reconstructed aquaponics systems propagating tomatoes in terms of height, weight, girth, and number of fruits. The reconstructed aquaponics system’s higher growth yield results in a much more nourished crop than the traditional aquaponics system. It is superior in its number of fruits, height, weight, and girth measurement. Moreover, the reconstructed aquaponics system is proven to eliminate all the hindrances present in the traditional aquaponics system, which are overcrowding of fish, algae growth, pest problems, contaminated water, and dead fish.
Comparative analysis between traditional aquaponics and reconstructed aquapon...
Dillingham1975.biological evaluation of polymers
1. J. BIOMED. MATER. RES. VOL. 9, PP. 569-596 (1975)
Biological Evaluation of Polymers
I. Poly(methy1 Methacylate)
E. 0. DILLINGHAM, N. WEBB, W. H. LAWRENCE, and J.
AUTIAN, Materials Science Toxicology Laboratories, The University
of Tennessee,Centerfor the Health Sciences, Memphis, Tennessee 38163
Summary
A series of poly(methy1 methacrylate) formulations differing widely in chemical
and physical properties was employed for the evaluation of primary screening
methods for the assessment of acute toxicity. Materials and USP extracts of
materials were tested in parallel. Tissue culture, hemolysis, intradermal irrita-
tion, systemic toxicity, muscle implant and histopathologic responses were
determined for each of 27 formulations. A determination of the nonvolatile
methanol extractable components was carried out on each formulation. The
formulations varied with respect to percent, w/w, methyl methacrylate, N,N-
dimethyl-p-toluidine, stannous octoate, 3,4-diamino-toluene and, also, with
respect to curing conditions. Volatile components, primarily methyl methacry-
late, of three selected formulations were determined quantitatively by vacuum
distillation and mass spectrographic analysis.
Statistical analysis of the primary data indicated a significant correlation of
residue weight (methanol extractable) with hemolytic activity (r = 0.93) and
with the cumulative biological response (r = 0.9). Multiple linear regression
analysis of residue weights with hemolysis and intradermal irriation responses
gave the highest overall correlation (r = 0.96). Hemolytic activity and tissue
culture responses were significantly correlated (r = 0.87). It was concluded
that the observed variation of biological test results reflected significant differ-
ences in the toxicity of the test materials. The poly(methy1 methacrylate)
series examined was relatively low in toxicity and the biological tests examined,
particularly the in vitro tests, were found to be responsive to formulation and
curing conditions which indicated their suitability for primary toxicity screening.
INTRODUCTION
Synthetic polymeric materials have found wide use in medical
practice as restorative structural substances and as components of
implanted prosthetic devices. At the present time, the selection
569
@ 1975by John Wiley & Sons, Inc.
2. 570 DILLINGHAM ET AL.
and use of a specific polymer material rests primarily on the judg-
ment of the investigator or practitioner, since there are no generally
accepted criteria or standards for preclinical evaluation. The
variable clinical success with a given polymer material, and the fact
that many different sources and formulations are available, points
to the need for evaluation prior to introduction into medical or dental
practice. Thisstudy was directed toward an evaluation of procedures
for preclinical evaluation.
Poly(methy1 methacrylate), PMMA, a polymer which has been
widely used as a restorative material and as a componcnt of pros-
thetic devices, was employed in an investigation of physical, chemical,
and toxicological properties with respect to formulation variables.
The principal objective of the work was the discrimination of test
methods providing the highest correlation between formulation and
toxicological parameters.
Biological Compatibilityof Poly(methy1Methacrylate)
Poly(methy1 methacrylate) has been used extensively as a pros-
thetic material in dental and mandibular corrections, and as a bone
cement in hip joint restructure. When used as a dental restorative
material, there are reports of little or no inflammatory response,1-4
while others have reported inflammation, formation of connective
tissue, and loss of bon~.~-'O Studies of orthopedic restorations
(1960-1970) indicated no lasting adverse effects of PMMA.11-13
Two long-term studies reported carcinomas associated with PMMA
restorati~ns.'~-'~Adverse response was noted in some cases of
"cold cured" restorations which suggested toxicity from the residual,
unpolymcrized, methyl methacrylate monomer. The clinical use of
PMMA in orthopedic surgery was approved by the Food and Drug
Administration in October, 1971. Since that time, many adverse
effects of PMMA bone cement have been Cardiac
arrests and pulmonary complications during hip joint repair with
PMMA have been noted; the adverse responses, e.g., hypotension16.
18,23,24928*30,35 or pulmonary embolism, 21,22e25-27 were in some cases
attributed to free monomer. Other reports have cited contact
dermatiti~,~Zchanges in urinary level of amino nitrogen,33 and
histological response of tissues with respect to blood levels.34 Homsy
et a1.35determined blood levels and clearance of methyl methacrylate
monomer in humans and canines exposed to subcutaneous PMh4A
implants and intravenous administration of the monomer.
3. BIOLOGICAL EVALUATION OF PMMA 571
Adverse biological response to plastic materials is primarily re-
lated to the kind and quantity of low molecular weight residual
components having adequate solubility in tissue fluids to leach from
the material into adjacent tissues and the systemic circulation.
The physical properties and chemical composition of the surface of
the material also influmce compatibility with tissues, hemolytic
activity and thrombogenic activity.
A polymeric material such as PMMA can possess a wide range of
toxic potentials, depending upon the kind and quantity of starting
materials usrd in its formulation and the physical history of the
polymer. Each polymer formulation must, therefore, be considered
to have a unique potential toxic liability.
MATERIALS AND METHODS
Formulationof Poly(methy1Methacrylate)
The starting materials for PMMA formulations are given in
Table I. The formulations were varied systematically with respect
to methyl methacrylate (MMA) and N,N-dimethyl-p-toluidinr
(DPT) concentrations. Stannous octoate (SO) and 3,4-diaminoto-
luene (DAT) were each used in two formulations. Details of for-
mulations were designed to provide diversity of final polymer proper-
TABLE I
Starting Materials: Poly(methy1Methacrylate) Formulations
Component Source
Hue-Lon Clear: poly(methy1methacrylate);
polymer beads with initiator, benzoyl
peroxide ( <2%)
Hue-Lon Liquid: methyl methacrylate (MMA)
with stabilizer, hydroquinone (<0.006%),
and crosslinkingagent, ethylene di-methacry-
late (l-Z%)
N,N-dimethyl-p-toluidine (DPT)
3,4-diaminotoluene(DAT)
Stannous octoate (SO)
L. D. Caulk Company
P. 0.Box 359
Milford, Delaware
J. T. Baker Chemical Co.
Phillipsburg, New Jersey
Eastman Chemical Co.
343 State Street
Rochester, New York
Dow-Corning
P. 0. Box 5074
Atlanta, Georgia
4. 572 DILLINGHAM ET AL.
ties and have no direct relationship to specific end uses, although
highly cured formulations without additives approximated those
employed in the fabrication of prosthetic devices such as dentures.
The basic formulation procedurc consisted of mixing monomer
(Hue-Lon Liquid, MMA) and polymer beads (Hue-Lon Powder),
1:2, w/w, until the product reached a nontacky dough stage. Thr
dough was transferrrd to standard dental stone molds lined with
aluminum foil and pressure (20psi) was applied. The press asscmbly
was heatrd in a 65°C water bath 45 rnin and quenched in an ice bath
for 1hr (Table11, Code 1). The product, a hard, transparent plastic
sheet 5 mm thick, was stored at 4°Cuntil usrd. Table I1 describes
the variations in curing conditions and additives employed in the
formulation of PMRIA test materials. Additives, including excess
TABLE I1
Formulation and Curing of Poly(methy1 Methacry1ate)a
Formulation
Code Additives, O/~(W/W)~
______ _ ~
No. I I1 Method
1
2
3
4
5
6
7
8 IMMAc
6.0 DPT
4.0 DAT
4.0 SO
.6.0SO
Monomer pipetted into polymer powder (1 :2,
w/w) with stirring (20 min) ;'dough placed in
dental press (20psi, 65"C, 45 min) followed by
O'C, 1hr.
# I procedure except cured at 65"C, 18 hr,
followed by lOO"C, 1 hr, and cooled 15 min
with tap water.
#1 Procedure
# 1 procedure except DPT added 5 min after
initiating stirring.
DAT added to monomer and suspension
added to polymer powder (monomer: polymer,
l:l, w/w); stirred until dough-like (about 20
rnin); cured 65"C, 18 hr, cooled (tap water).
# 1procedure except SO added at 5 min.
#6 Procedure
Monomer added to polymer powder (l:l,
w/w), stirred 65 min; cured (room temp.,
1hr) followed by O"C, 1 hr.
~~
(continued)
5. BIOLOGICAL EVALUATION OF PMMA 573
TABLE 11-(Continued)
Formulation
Code Additives,
No. I
9 SMMA
10 SMMA
11 PMMA
12 2MMA
13 2MMA
14 SMMA
15 2MMA
16 2MMA
17 4 MMA
18 4MMA
19 4MMA
20 GMMA
21 GMMA
22 GMMA
23 GMMA
24 GMMA
25 GMMA
26 6MMA
27 GMMA
28 2MMA
%(W/WP
I1
0.25 DPT
0.75 DPT
1.25 DPT
0.25 DPT
0.75 DPT
1.25 DPT
0.25 DPT
0.75 DPT
1.25 DPT
6.0 DPT
0.25 DAT
0.5 DAT
Method
# 1procedure except cured at room tempera-
ture, 1hr, followed by O'C, 1 hr.
#2 Procedure
# 1 procedure except cured at 65"C, 90 min;
100°C, 1 hr, and cooled (tap water) 15 min.
# 1 procedure execpt cured at 65"C, 90 min;
lOO"C, 1 hr; cooled, room temperature.
# I Procedure
#4 Procedure
#4 Procedure
#4 Procedure
#4 Procedure
#4 Procedure
#4 Procedure
# 1Procedure
#1 Procedure
#4 Procedure
#4 Procedure
#4 Procedure
#4 Procdeure
# 1 procedure except DAT mixed with poly-
mer powder before adding monomer.
# 26 Procedure
#9 Procedure
*Abbreviations: MMA = methyl methacrylate; DPT = N,N-dimethyl-p-
bAmount added &s a percent of the total weight of the stated base formulation.
OExcess MMA was added to the MMA of the base formulation before mixing.
toluidine; DAT = 3,4-diaminotoluene;SO = stannous octoate.
monomer, were added as a wt '% of the total weight of the basic
formulation.
Biological Tests
Agar Overlay Tissue Culture Test.-Tissue culture toxicity was
evaluated using nonreplicating mouse fibroblast cells.36 Monolayers
of cells in Petri dishes were covered with a thin layer of agar contain-
ing minimum nutrients to maintain cell viability. The cells were
6. 574 DILLINGHAM ET AL.
vitally stained with neutral red and the test samples were applied
to the surface of the agar, 2 samples per Petri dish, along with one
positive (toxic) control material and one negative (nontoxic) control
material.* The standard assay consisted of duplicate test plates.
Solid samples were applied as squares of approximately 1 cm.
Liquid samples (USP extracts) were applied to 1cm filter paper assay
disks, 0.2 ml per disk. The test plates were incubated for 24 hr
and the monolayer responses reported in the form of a Response
Index (RI), as shown in Table 111. A toxic response was detected
by loss of the vital dye followed by lysis if the concentration of leach-
able toxic components was high enough. The zone size and percent
of cells lysed within the zone were determined microscopically,
although zones were apparent macroscopically.
Extraction of Materials for Biological Tests.-The USP procedure37
for extraction of materials (4g materials/20 ml extraction medium,
121"C, 1 hr) was employed to obtain extracts for both in vitro and
in vivo tests. The PRIMA material was prepared for extraction by
breaking the 5 mm thick sheet into small pieces. Four or 5 pieces
of approximately equal dimensions totaling 4 g were selected for
extraction. Cottonseed oil (C), polyethylene glycol-400 (P), and
saline (S) extracts were prepared for tissue culture (TC), intradermal
irritation (ID) and systemic toxicity tests (IV or IP), Table IV.
All tests were carried out on each extract within 6 hr of extraction.
Hemolysis Test.-Five g of material (prepared as for USP extraction
was added to 10 ml of saline (0.9% sodium chloride, aqueous) in
.16 X 150 mm assay tubes and equilibrating at 37°C for 30 min.
Freshly collected rabbit blood (1ml of 2y0 sodium oxalate per 20 ml
of blood) was diluted with saline to a positive control optical density
of 0.9-1.0. Two-tenths ml was added to each assay tube and mixed
by gentle inversion, followedby incubation, 37°C for 1hr. The tubes
were centrifuged, 500 X 9, 5 min, and the supernatant removed for
determination of optical density (O.D.) at 545 nm (saline reference).
The negative control was saline and blood only. The positive control
(loo'%hemolysis) was obtained by addition of 0.2 ml blood to 10 ml
of 0.1% sodium carbonate. Treated and control tubes were handled
* Positive control: Poly(viny1 chloride) tubing demonstrated to be consistently
Negative control: Polyethylene film demonstrated to be consistentlycytotoxic.
noncytotoxic.
7. BIOLOGICAL EVALUATION OF PMMA 57.5
TABLE 111
Rating Scales For Biological Response
Agar Overlay Tissue Culture Test:
Zone Index (ZI)
0 No detectable zone around or under sample
1 Zone limited to area under sample
2 Zone not greater than 0.5 cm in extension from sample
3 Zone not greater than 1.0 cm in extension from sample
4 Zone greater than 1 cm in extension from sample but not
5 Zone involving the entire plate
0 No observable lysis
1 Less than 20% of zone lysed
2 Less than 40% of zone lysed
3 Less than 60% of zone lysed
4 Less than 80% of zone lysed
5 Greater than 80% lysis within zone
involving the entire plate
Lysis Index (LI)
Response Index (RI) = ZI/LI
Percent Hemolysis (HY,): 0 to l0Oy'
Percent Inhibition fo Cell Growth (ICGY,): 0 to 100%
Rating Scalea
Hemolysis Test:
Inhibition of Cell Growth:
Intradermal Irritation (I. D.):
0 No detectable irritation
1
2, 3, 4
Systemic Toxicity (I. V. or I. P.):
Intramuscular Implant Test (IM):
.5 Minimal irritation detected
Very slight but distinct irritation
Increasing intensity of inflammation and wheal
Rating Scale = Number of deaths after 7 days: 0 to 5
Rating scale was analagous to that for I. D.: intensity of gross visible
inflammation and necrosis around implant primary factors.
Histopathologic Rating (HR) :
Rating Scale:
0
1 Minimal response detected
2, 3, 4
Not different from negative control
Increasing tissue reaction around implant; the degree
of necrosis primary factor
UOriginal data converted as follows for computer analysis:
0 = 0 ; % = .5, f = 1 , 1 = 2 , 2 = 3 , 3 = 4 , > 3 = 5
10. 578 DILLINGHAM ET AL.
TABLE IV-A
Explanation of Headings: Table IVa
M = Material sample
C = USP cottonseed oil extract
P = USP polyethylene glycol-400 extract
S = USP saline extract
H = Hemolysis, % (polymer test sample)
MI = Intramuscular implant response
I D = Intradermal irritation response
IP = Systemic toxicity, I. P. administration
IV = Systemic toxicity, I. V. administration
HR = Histopathologic rating of MI
CI = Cumulative biological index (see under “Statistical Analysis”)
ICG = Inhibition of cell growth, %; tissue culture
HE^ = Hemolysis, yo(USP saline extract of polymer)
IRW = Weight of methanol extractable substances,%
93ee Table I11for rating scales.
alike. The assay was carried out with 5-fold replication, and the
percent hemolysis was estimated using the average O.D. values:
Hemolysis yo =
O.D. (treated) - O.D. (negative control)
x 100
O.D. (positive control) - O.D. (negative control)
The hemolytic activity of USP saline extracts was carried out in
the above manner except that the blood was added directly to the
saline extract.
The influence of surface properties of materials on hemolytic
activity was determined by carrying a set of assay tubes in parallel
with a standard assay of a material, but without the addition of blood.
At the end of the 1 hr incubation period, the standard set with blood
was centrifuged and assayed normally. The set without blood was
decanted into new assay tubes, taking care not to transfer any of the
material test sample, 0.2 ml blood was added to the decantate,
incubated for 1 hr at 37”C, and assayed normally.
Inhibition of Cell Growth.-Distilled water extracts of materials,
USP, were incorporated into Eagle’s medium* 38 at a final extract
* Modified Basal Medium Eagle supplemented with 5% newborn calf serum,
1% tglutamine, and 50 mcg/ml of streptomycin sulfate, magnesium being
added as magnesium chloride, 177 mg/l.
11. BIOLOGICAL EVALUATION OF PMMA 579
concentration of 50% with respect to the original extract by mixing
equal volumes of double strength Eagle’s medium and distilled
water extract. Growth in the extract-treated medium was compared
to growth in the untreated Eagle’s medium. Two X 105 mouse
fibroblast cells (strain L-929) in Eagle’s medium were added to each
of 20 assay tubes. The tubes were centrifuged, 500 X g, 5 min,
and the medium decanted, taking care to maintain asepsis and not to
lose cells. Ten received 2 ml Eagle’s medium and ten received 2 ml
treated medium. Five of the treated set and 5 of the control set
were centrifuged, decanted, washed twice with saline (centrifugation),
and stored at 4°C until assayed for cell protein by the Lowry modifi-
cation of the Oyama and Eagle 40,41 protein assay procedure (zero-
time controls). The remaining 10 tubes were incubated for 72 hr
(37OC, 5% COn-air atmosphere), centrifuged, washed, and assayed
for total protein along with the zero-time controls. The inhibition
of cell growth was calculated as the decrease in net (72 hr minus zero-
time) cell protein in the treated set as a percent of the net cell protein
of the control set.
Intradermal Irritation Test.-Irritant response42was determined
by injection of 0.2 ml of a USP extract (C, P, or S) of a test material
intracutaneously into 10 sites of each of 2 rabbits, previously clipped
of hair on the dorsal surface. Two-tenths ml of a negative control
solution (saline) and a positive control solution (20% ethyl alcohol)
were injected intracutaneously in each animal. After 3 days the
irritant response was rated on a 6-point scale (Table 111) with respect
to intensity. The protocol was essentially that described in the
United States Pharmacopeia, XVIII.37
Systemic Toxicity Test.-Extracts were administered to 5 mice with
5 control mice receiving the untreated extraction solution. Saline
extracts were administered intravenously (IV), 50 ml/kg. Poly-
ethylene glycol-400 and cottonseed oil extracts were administered
intraperitoneally (IP), 50 ml/kg and 10 ml/kg, respectively. The
animals were observed for signs of toxicity and mortality at 1 week
(0-5 scale, Table 111).
Intramuscular Implantation Tests.-The protocol was essentially
that described in the United States Pharmacopeia, XVIII.37 A
trocar needle was employed to implant thin sections of the test mate-
rial into the paravertebral muscle of rabbits, lightly anesthetized
with sodium pentothal and shaved on the dorsal surface. Each
12. $80 DILLINGHAM ET AL.
animal received 2 negative (nontoxic), 2 positive (toxic) control
implants, same control materials as used in tissue culture, and 6
implants of the test material. After 1week the rabbits were sacri-
ficed; the implant sites were surgically removed and examined for
grosstoxicity. The intensity of response was recorded using a 6-point
scale (Table 111). The tissue including the implantation site was
preserved in formalin, examined histologically, and a Histopatho-
logic Rating, HR,41was recorded on a &point scale (0-4, Table 111).
Twelve-Week Intramuscular Implantation Test.-This test followed
the identical protocol for the 1week implantation test, except that
14rabbits were implanted with material tested and 1rabbit sacrificed
and evaluated each week.
Physical and Chemical Analytical Procedures
VolatileComponentsof PMMA Formulations.-Volatile components
of 3 selected PMMA Samples (4,7, and 27, Table 11)were obtained
by heating 1.5-2.5 g of polymer under vacuum (85°C f 3"C, 10-3
torr) in an all glass system for 90 min. The collection vessel, a
5 mm i. d. glass tube (- 180°C)was heat-sealed, removed from the
system, the weight of volatile material determined and the contents
analyzed by gas chromatography and mass spectrometry, Table V.
Extraction of Polymer Formulations.-Methanol was used for the
extraction of all PMMA formulations (Table 11). The test sample
was broken into small pieces and 20-25 pieces of approximately
equal size totaling 10 g (=I=0.1mg) were extractedin 150ml of meth-
anol with continuous agitation, 23"C, for 24 hr. After extraction,
the solvent was decanted and held at 4°C until used.
Three samples (4, 7, and 27, Table 11)employed for the determina-
tion of volatile components were subsequently extracted with 100ml
of methanol for 15 hr by refluxing under ambient conditions (bp
64.5 =t0.3"C). The solvent was decanted and evaporated at 50°C.
The residue was weighed and analyzed by infrared and mass spec-
trometry.
Quantitation of Methanol Extractable Residue.-Eighty to 90 ml of
the 24 hr extract used in the biological tests was reduced to approx-
imately 10ml under reduced pressure in a rotary evaporator (40°C).
The concentrate was quantitatively transferred to a tared crucible,
reduced to dryness (25"C, 4 days, 15-20 mm Hg), and weighed. The
14. 582 DILLINGHAM ET AL.
amount of residue (RW, % w/w) was calculated as a percent of the
original sample weight.
Gas Chromatographic Analysis of Methanol Extract.-Fifty ml of
methanol extract was concentrated to 10 ml on a rotary evaporator,
and further reduced to approximately 2 ml under a stream of dry
nitrogen in a graduated cylinder. The final volume was recorded
(=t0.05ml). The sample was filtered on Whatman No. 1 filter paper
and chromatographed on a Varian Model 2100 Gas Chromatograph
with flame ionization detection.
StatisticalAnalysis
A stepwise multiple linear regression45was performed on residue
weight %, versus the 9 biological test results showing significant
variation. A similar analysis of hemolysis % versus other biological
tests was carried out. A test was also made of the correlation betwecn
the Cumulative Biological Index (CI) and residue weight %. CI
was defined as the sum of all biological test results, except inhibition
of cell growth %, normalized to a value of 100 for the maximum or
positive control response. In the case of tissue culture data, the
sum of Zone Index (ZI, maximum of 5) plus Lysis Index (LI, maxi-
mum of 5 ) was normalized to 100 (e.g., the sum was multiplied by
10).
RESULTSAND DISCUSSION
Twenty-seven formulations of PMMA were tested for toxicity.
Table I1 presents the formulation data, and Table IV, the primary
biological test results, along with residue weight yoof the methanol
extractable components. The PMMA formdations gave a wide
range of toxic responses in vitro, but relatively little response in vivo.
The residue weight yo showed sufficient systematic quantitative
variation for statistical analysis. Gas chromatography and infrared
and ultraviolet absorption data obtained on extracts or residues
were qualitatively related to formulation and curing protocols, but
were not sufficiently quantitative for statistical analysis.
CumulativeBiological Index
The correlation of the Cumulative Biological Index (CI)” with
The apparentresidue weight % was significant (r = 0.9), Figure 1.
*Defined under “statistical analysis.”
15. BIOLOGICAL EVALUATION OF PMMA 583
CUMULATIVE BIOLOGICAL INDEX
Fig. 1. Poly(methy1methacrylate):regression of residue weight on cumulative
The curves indicate the approximate upper andbiological response (T = 0.90).
lower limits of biological response.
upper and lower limits of CI, indicated by the 2 linear curves,
differed by approximately 150 CI units over the observed range of
residue weights. The formulations that included N,N-dimethyl-p-
toluidine (DPT), an activator of the polymerization reaction, showed
uniformly low biological response and residue weights of 1% or less,
which was consistent with the assumption that free monomer contrib-
utes significantly to biological response. The addition of 6% DPT
(formulation 4) resulted in one of the lowest values of CI. DPT
was detected by gas chromatography in methanol extracts of all
samples formulated with 20.75% DPT. Biological response was
significantly affected by the presence of DAT (formulations 5, 26,
and 27).
Benzoyl peroxide and its degradation products may contribute
to biological response and residual benzoyl peroxide would be expected
to be greatest in the less polymerized formulations which showed the
highest biological response. Benzoic acid, a primary degradation
product of benzoyl peroxide, should be greatest in the more highly
polymerized formulations. Hydroquinone, and unstable compound,
16. 584 DILLINGHAM ET AL.
was also present. The presence of these compounds and their
relative leachability may contribute to the 150 CI variation of CI
observed.
The influence of curing conditions was evident in formulations
9-13 (Table VI), which were identical in composition, but,were cured
TABLE VI
Influence of Curing Conditions on Biological Response
Poly(methy1Methacrylate)*
Degree of Tissue
Sampleb Curing Culture Hemolysis CI
9 Lowest 4/3 84 394
13 2/2 61 191
11 1/1 1 116
12 o/o 0 30
10 Highest 0/0 1 81
a2y0 excess monomer.
bSee Table 11.
under different conditions. The degree of curing increased in the
order 9, a highly quenched formulation, 13, 11, 12 and 10. The
latter two were raised to 100°C for the last hr of curing and were
considered highly cured. The CI values for those formulations were
394, 191, 116, 30 and 81, respectively, which further supported the
assumption that free monomer, a function of curing conditions, was
a significant factor in the biological response of PMMA formulations.
Curing conditions were also found to be correlated with the hemolytic
activity of both the materials and USP saline extractsof the materials;
see Tables I1 and IV.
The regression of RW on CI and the empirical correlation of CI
with curing conditions and type of additives in the formulations in-
dicated that the biological tests employed provided a sensitive index
of leachable toxic components. The fact that the lower limits of CI
showed a linear regression through the origin (Fig. 1) supported the
conclusion that little or no biologically inert substances (e.g., polymer)
contributed to RW. It is also consistent with the conclusion that the
variability of CI at a given RW reflects differences in biological
activity resulting from differential leachability of low molecular
weight components of diffcrent formulations.
17. BIOLOGICAL EVALUATION OF PMMA 585
The results of a 5 week study of reproducibility of biological test
results are given in Table VII. The major part of the variation
could be accounted for on the basis of decreasing biological activity
with respect to time, particularly apparentin the in vivo andhemolysis
results. It was concluded that the principal component of variation
was differences in biological activity of samples rather than the
variability of test results.
The Influence of SampleAge on Biological Test Results
Table VIII summarizes tissue culture and hemolysis test results
obtained on samples of different ages. The tissue culture test
results varied little for tests on materials and on extracts of materials.
However, the hemolysis test results declined significantly with time,
with the exception of formulation 5 which contained a high (4%)
level of DAT. There was an overall correlation of 0.87 between
tissue culture and hemolysis test results for samples assayed within
the first 50 days after formulation. Residual hemolytic activity of
1.9% or higher (128 to 206 days after formulation ) was consistently
associated with a distinct tissue culture response (RI = 2/2 or
higher). The relative insensitivity of tissue culture test results with
regard to sample age supports the selection of tissue culture tests for
comparative studies, although under fixed conditions the hemolysis
test provides essentially the same relative information and is con-
siderably easier to perform.
Chronic Toxicity of PMMA Implants
The results of a 12 week study of muscle implants of formulations
3, 5, 6, and 24 are shown in Table IX. The highly cured sample
(formulation 5) showed the lowest overall response in spite of the
presence of DAT, which in other tests gave a very high overall re-
sponse (CI = 474). There was no significant response after 1week
for any of the formulations, and only formulation 6 with stannous
octoate gave a distinct response (HR = 2) at 1week. H R ratings
of 2 for all samples at 3 days indicated a significant degree of initial
tissue reaction (primarily due to trauma);however, chronic toxicity
was not great for the 4 samples tested.
CorrelationsBetween Tests
The multivariate correlation of residue weight % (RW) with
biological tests (Fig. 2) indicated that residue weight was most
19. BIOLOGICAL EVAL,UATION OF PMMA 587
D
W
>
W
m
0
a
m
c
2
RW=0.65(H,o/o)t .93 (lD,C) + .29
r = 0.96
I I I I I I I 1 I
0 I 2 3 4 ' 5 6 7 8 9 10 I1 12
RW, PREDICTED
Fig. 2. Prediction of residue weight using hemolytic activity of material
The
Formulation numbers are indicated for
samples and the cottonseed oil extract intradermal irritation responses.
curve is the line of perfect correlation.
selected data points.
highly correlated with hemolysis and intradermal irritation of cotton-
seed oil extracts.
RW % = 0.65(H %) +0.93(ID,C) +0.29 T = 0.96
Intradermal irritation (ID,C) contributed to the correlation only
slightly. The univariate correlation coefficient of RW % with H %
was 0.93.
The correlation of H '% with all other biological tests (Fig. 3)
indicated it to be most highly correlated with tissue culture param-
eters.
H % = 14.9 (ZI) + 11.4 (LI) - 12.2 T = 0.87
23. BIOLOGICAL EVALUATION OF PMMA
100
90
80
70
60
50
40
30
20
10
591
-
-
-
-
-
-
-
-
-
-
(3)
-@-
-10 0 lo I 2
0
W
>
[L
W
v)
0
m
8
I
0
0
H ,X PREDICTED
Fig. 3. Prediction of hemolytic activity using tissue culture response: ZI(M) =
Zone index of material samples; LI(S-1) = Lysis index of USP saline extracts.
The curve is the line of perfect correlation. Numbers in parentheses indicate
the number of values at the indicated point.
The PMMA formulations employed in this study were relatively
low in toxicity, showing few significant in vivo responses, which
accounts for their lack of significant contribution to the above
correlations. The correlations obtained with polymer formulations
of higher toxicity will be presented in a second publication.
Inhibition of Cell Growth by Extracts.-A striking difference was
observed between the percent inhibition of cell growth (% ICG) by
extracts and the other biological data. All 12 extracts assayed com-
pletely inhibited growth (131-253%) and showed no signficant
trend regarding formulation variables (least significant difference,
95% confidence = 12%). The ID5, (concentration producing 50%
inhibition of growth) of MMA was determined to be 2.0 X M
24. 592 DILLINGHAM ET AL.
(moles/liter). The intrinsic toxicity (slope of the dose-response
curve) was 3.7 X lo2% inhibition/mole. On the assumption that
methyl methacrylate was the active component in the ICG extracts,
concentrations in excess of 10" M were indicated for the extracts.
Mir et a1.4+48 reported 17% inhibition of contraction of guinea pig
illeum at 4.6 x 10-3 M ; 42% depression of blood pressure, 9.6%
depression of heart rate, and 65% increase in respiration rate, in
male dogs at 1.4 X They also reported 50% depression
of heart rate (8 x M ) ,
and coronary flow (1 X M ) in isolated rabbit heart assays.
Approximately 2% ethylene dimethacrylate was present in the
monomer employed in the present study and those reported by Mir
et al. It was detected in some of the methanol extracts of less
well-polymerized formulations of PMMA, but its contribution to
biological response was not determined. Since the limit of gas
chromatographic detection was f 1 ng, it was unlikely that ethylene
dimethacrylate was a significant factor for the more highly cured
formulations where it was not found in the methanol extract.
M .
M ) ,force of heart contraction (1 X
The Influence of Additives on Hemolytic Activity
Fifteen selected formulations were assayed in parallel for hemo-
lytic activity of the material and USP saline extracts of the material
(Fig. 4). There is no significant difference in the rank order of
response in the 2 assay systems, which indicated that the hemolytic
activity was due to readily soluble components of the formulations,
and that the physical presence of the solid material in the assay system
had no apparent effect. In view of the very steep dose-response
curves typically obtained in the hemolysis assay, consistency of the
2 rank orders was excellent.
Physical and Chemical Analyses of PMMA
Volatile Components.-Since the routine extraction and concen-
tration procedure used for gas chromatographic analysis of the
methanol extracts did not recover the highly volatile components of
the extracts, a vacuum distillation procedure which permitted quan-
titative recovery of those components was used with 3 typical
formulations, 4, 7 and 27 (Table V). Formulation 4, which con-
tained 6% DPT and was very low in biologica1,responses (CI = 91),
gave 0% volatile material. Similar low biological responses were
25. BIOLOGICAL EVALUATION OF PMMA 593
100
40
20
W
OAT
Fig. 4. Poly(methy1 methacrylate) : Rank order of hemolytic activities of
M = methylUSP extracts and material samples with respect to additives.
methacrylate (see Table IV).
obtained with all formulations containing DPT or highly cured sam-
ples without additives other than excess monomer. Formulation
7, with 6% stannous octoate, contained 1.1% volatile components
and had moderate biological activity (CI = 130.7). Formulation
27, with 6% excess monomer and 0.5% DAT, contained 11.0%
volatile material and was very toxic (CI = 408). Comparison of the
biological response of the three formulations indicated the volatile
component, identified by infrared spectrophotometry and mass
spectrometry to be methyl methacrylate, contributed substantially
to the biological response and both parameters were correlated with
the level of methanol extractable components. The relatively com-
plete curing obtained with DPT under the conditions of curing
used in this study cannot be extrapolated to conditions of "cold
curing" employed in situ, since all formulations with DPT were
cured in a dental press at elevated temperatures. Formulations 8
and 9 (Table 11),which contained 1 and 2% excess monomer re-
spectively, and cured at ambient temperature, gave two of the
26. 594 DILLINGHAM ET AL.
highest biological responses (CI = 318 and 394, respectively), a
further indication of the importance of free monomer in influencing
biological response.
Gas Chromatographic Analysis of Extracts.-Methanol extracts
of formulations having 2 0.75% DPT contained quantities of DPT
correlated with concentrations in the initial formulation, The
quantity of ethylene dimethacrylate extracted by methanol was
inversely proportional to the degree of curing, none being found (less
than 1ng) in the extracts of highly cured samples. These two com-
pounds and MMA were the principal components found in methanol
extracts; other very minor unidentified components were sometimes
present.
CONCLUSIONS
The results of this investigation support the following conclusions.
1. The biological tests examined, particularly the in vitro tests,
are responsive to formulation and curing conditions of PMMA and
are suitable for primary toxicity screening.
The results of this study suggest that methanol-extractable
residues of PMMA formulations in excess of 0.7% are significantly
related to adverse (toxic) biological response, and that residue weights
might serve as a useful index of formulation viability in the quality
control of PiLIRIIA formulations when used in conjunction with
biological tests.
PMMA can be expected to vary widely in toxicity, depending
on formulation, curing conditions, and physical history of the
material, a higher degree of variability being expected for “cold
cured” formulations. A need for rigorous control of formulation
procedures and protocols, particularly for “cold curing,” is indicated.
In vitro tests, particularly tissue culture and hemolysis tests
on materials, are the most sensitive to formulation variables and yield
the greatest information on acute toxicity. Erst-round testing of
new formulations, especially those containing additives, should in-
clude the intramuscular implantation and the intracutancous irri-
tation test with a cottonseed oil extract. On the basis of this study,
it is unlikely that a formulation having significant acute toxicity
would not be detected using the above series of tests.
2.
3.
4.
27. BIOLOGICAL EVALUATION OF PMMA 595
5. The results of this investigation are pertinent primarily to the
evaluation of test procedures, and do not relate to specific end use
conditions of PMMA beyond the conclusions drawn above.
This study was supported through a research contract, no. 223-73-5231,of the
Food and Drug Administration, Washington, D. C.
The technical assistance of the staff of the Materials Science Toxicology
Laboratories, particularly Mrs. Alice Spralling, Mr. Michael Malik, Mrs. Eula
Baldwin, Mrs. Ramone Marquardt, and Dr. George Hung is gratefully acknowl-
edged. Computational serviceswere provided through USPHS Grant HL-09495.
References
1. S. Coronel, “Les RCsines Acryliques en Prothke et en Biologie,” Thesis,
Paris (1947).
2. M. Hodash, M. Povar, and G. Shklar, J . Periodontob, 39, 187 (1968).
3. M. Hadash, M. Povar, and G. Shklar, J . Prosthetic Dent., 22, 371 (1969).
4. W. A. Castelli, C. E. Nasjleti, D. F. Huelke, and R. Diax-PCrez, J. Dent.
Res., 50, 414 (1971).
5. D. E. Brown, Arch. Otolaryngol., 88, 283 (1968).
6. C. E. Nasjleti, W. A. Castelli, and B. E. Keller, J . Dent. Res., 51,1382 (1972).
7. J. Waerhaug and H. Zander, Oral Srug., Oral Med., Oral Path., 9,46 (1956).
8. R. Narang and H. Wells, Znt. Assoc. Dent. Res. Program and Abstracts of
Papers, 259, (1971).
9. J. C. Strain, J . Prosthetic Dent., 18,465 (1967).
10. T. E. Stungis and J. N. Fink, J. Prosthetic Dent., 22, 425 (1969).
11. J. Charnley, .I. Bone Joint Surg., 42B, 28 (1960).
12. J. Charnley, J . Bone Joint Surg., 50B. 288 (1968).
13. J, Charnley, Acrylic Cement in OrthopedicSurgery, Williams and Wilkins Co.,
Baltimore, 1970.
14. B. S. Oppenheimer, E. T. Oppenheimer, A. P. Stout, M. Willhite, and
I. Danishefsky, Cancer, 11, 204 (1958).
15. N. E. Stinson, Brit. J . Exp. Pathol., 45, 21 (1964).
16. T. A. Thomas, I. C. Sutherland, and T. D. Waterhouse, Anaesthesia, 26,
298 (1971).
17. P. Frost, Brit. Med. J., 3, 524 (1970).
18. H. Phillips, P. V. Cole, and A. W. Lettin, Brit. Med. J., 3, 460 (1971).
19. J. N. Powell, P. J. McGrath, S. K. Lahiri, and P. Hill, Brit. Med. J., 3, 326
(1970).
20. E. R. Kepes, P. S. Underwood, and L. Becsey, J. Am. Med. ASSOC.,222,576
(1972).
21. C. M. Evarts and R. J. Alfidi, J . Am. Med. Assoc., 225, 515 (1973).
22. C. A. Cohen and T. C. Smith, Anesthesiology, 35, 547 (1971).
23. A. F. Newens and R. G. Volz, Anesthesiology, 36, 298 (1972).
24. D. J. Peebles, R. H. Ellis, S. K. K. Stride, and B. R. J. Simpson, Brit. Med. J.,
1, 349 (1972).
28. 596 DILLINGHAM ET AL.
25. J. H. Adams, D. I. Graham, E. Mills, and T. G. Sprunt, Brit. Med. J., 3,740
(1972).
26. P. Cole, H. Phillips, A. Lettin, and D. Dandy, Brit. Med. J., 4, 231 (1972).
27. A. W. Fowler, Brit. Med. J., 4, 108 (1972).
28. G. J. C. Brittain and D. J. Ryan, Brit. Med. J., 4, 667 (1972).
29. M. J. Nicholson, Anesthesia and Analgesia, Current Res., 52, 298 (1973).
30. K. C. Kim and M. A. Ritter, Clin. Orthop., 88, 154 (1972).
31. R. H. Ellis, Brit. Med. J., 1, 236 (1973).
32. J. S. Pegum and F. A. Medhurst, Brit. Med. J., 2, 141 (1971).
33. A. P. Suvorov, Gig. Sanit., 35, 106 (1970) (Rus).
34. C. J. Holland, K. C. Kim, M. I. Malik, and M. A. Ritter, Clin. Orthop., 90,
262 (1973).
35. C.A. Homsy, H. S.Tullos,M. S. Anderson, N. M. Differante, and J. W. King,
Clin. Orthop., 83, 317 (1972).
36. W. L. Guess, S. A. Rosenbluth, B. Schmidt, and J. Autian, J . Pharm. Sci.,
54, 1545 (1965).
37. The United States Pharmacopeia, XVIZZ, Mack Publishing Company,
Easton, Pennsylvania, 1970.
38. T. C. Butler, J. Pharmacol. Exp. Ther., 92, 49 (1948).
39. V. Oyama and H. Eagle, Proc. SOC.Exptl. Biol. Med., 91, 305 (1956).
40. 0.H. Lowry, N. J. Rosebrough,A. L. Farr, and R. J. Randall, J . Biol. Chem.,
193, 265 (1951).
41. 0.Folin and U. Ciocalteau, J . Biol. Chem., 73, 627 (1927).
42. D. Powell, W. H. Lawrence, J. Turner, and J. Autian, J . Biomed. Mater.
Res., 4, 583 (1970).
43. J. E. Turner, W. H. Lawrence, and J. Autian, J . Biomed. Mater. Res., 7, 39
(1973).
44. J. Cornfield and N. Mantel, Amer. Stat. Assoc. J., 45, 181 (1950).
45. A. Ralston and H. Wilf, Mathematical Methodsfor Digital Compufers,Wiley,
New York, 191 (1964).
46. G. N. Mir, W. H. Lawrence, and J. Autian, J. Pharm. Sci., 62, 778 (1973).
47. G. N. Mir, W. H. Lawrence, and J. Autian, J. Pharm. Sci., 62, 1258 (1973).
48 C. N. Mir, W. H. Lawrence, and J. Autian, J . Pharm. Sci., 63, 376 (1974).
Received November 8,1974
Revised February 4, 1975