This document discusses release kinetics and various drug release mechanisms and models. It begins by outlining the objectives of studying release kinetics, including predicting in vitro release and release profiles. It then covers key topics like modified Noyes-Whitney equation, drug release mechanisms, and theoretical models for diffusion, swelling, and erosion controlled systems. Specific models discussed in detail include zero order, first order, Hixson-Crowell, and various swelling and erosion models. The document provides information on interpreting release kinetics data using these mathematical models.
it describes the controlled drug release by diffusion or dissolution or both or swelling or erosion and which kinetics it follows either zero,first , higuchi or peppas
The document discusses various kinetic models that can be used to describe drug release from pharmaceutical formulations, including zero-order, first-order, Higuchi, Korsmeyer-Peppas, Hixson-Crowell, Weibull, Baker-Lonsdale, Hopfenberg, Gompertz, and sequential layer models. It provides the key equations and applications of each model, with graphics to analyze drug release over time. The models can help optimize drug release kinetics, predict effects of design parameters on release rates, and improve therapeutic efficacy and safety.
This document summarizes a seminar on oral controlled drug delivery systems presented by Sonam M. Gandhi. It discusses advantages and disadvantages of controlled delivery systems. Key types discussed include dissolution controlled, diffusion controlled, and combined dissolution/diffusion controlled systems using coatings or matrices. Other methods covered are ion exchange resins, pH dependent formulations, osmotic pressure controlled systems, and hydrodynamically balanced systems. Specific examples and equations are provided to explain the drug release mechanisms and rate determinations for several of these approaches.
GRDDS-Modulation to GI transit time,Approach to extend GI transit timeRESHMAMOHAN24
This document discusses approaches to extend gastrointestinal transit time by modulating gastric retention through gastroretentive drug delivery systems. It describes the physiology and motility patterns of the GI tract. Common approaches to prolong gastric retention time include high density systems, floating drug delivery systems, and effervescent systems. Floating drug delivery systems can remain buoyant in the stomach for extended periods without affecting gastric emptying.
The document discusses the physics of tablet compression. It describes the processes of compaction, consolidation and compression that tablets undergo in their production. It outlines the main stages of compression including particle rearrangement, deformation, fragmentation and bonding. It also discusses the forces involved and common compaction profiles and equations used to describe the process, including the Heckel and Kawakita equations. The document provides an overview of the key concepts and stages in understanding the physics behind tablet production through compression.
Preparation & stability of large & small volume parentralsROHIT
This document discusses parenteral formulations, including definitions, advantages, disadvantages, and classifications. It provides details on the preparation of small volume parenterals and large volume parenterals, including vehicles, buffers, preservatives, and other excipients used. It also covers the stability considerations for parenteral formulations and factors that influence syringeability, injectability, clogging, drainage, resuspendibility, and sedimentation of suspensions.
This document discusses rate-controlled drug delivery systems. It defines sustained release and controlled release, with controlled release implying predictability and reproducibility in drug release kinetics. An ideal controlled delivery system delivers drugs at predetermined rates for specified times. Rate-preprogrammed systems release drugs at pre-set rates through polymer membranes, matrices, or microreservoirs. Activation-modulated systems activate drug release through physical, chemical, or biochemical processes. Examples of activation methods include osmotic pressure, hydrodynamic pressure, vapor pressure, and magnetism.
it describes the controlled drug release by diffusion or dissolution or both or swelling or erosion and which kinetics it follows either zero,first , higuchi or peppas
The document discusses various kinetic models that can be used to describe drug release from pharmaceutical formulations, including zero-order, first-order, Higuchi, Korsmeyer-Peppas, Hixson-Crowell, Weibull, Baker-Lonsdale, Hopfenberg, Gompertz, and sequential layer models. It provides the key equations and applications of each model, with graphics to analyze drug release over time. The models can help optimize drug release kinetics, predict effects of design parameters on release rates, and improve therapeutic efficacy and safety.
This document summarizes a seminar on oral controlled drug delivery systems presented by Sonam M. Gandhi. It discusses advantages and disadvantages of controlled delivery systems. Key types discussed include dissolution controlled, diffusion controlled, and combined dissolution/diffusion controlled systems using coatings or matrices. Other methods covered are ion exchange resins, pH dependent formulations, osmotic pressure controlled systems, and hydrodynamically balanced systems. Specific examples and equations are provided to explain the drug release mechanisms and rate determinations for several of these approaches.
GRDDS-Modulation to GI transit time,Approach to extend GI transit timeRESHMAMOHAN24
This document discusses approaches to extend gastrointestinal transit time by modulating gastric retention through gastroretentive drug delivery systems. It describes the physiology and motility patterns of the GI tract. Common approaches to prolong gastric retention time include high density systems, floating drug delivery systems, and effervescent systems. Floating drug delivery systems can remain buoyant in the stomach for extended periods without affecting gastric emptying.
The document discusses the physics of tablet compression. It describes the processes of compaction, consolidation and compression that tablets undergo in their production. It outlines the main stages of compression including particle rearrangement, deformation, fragmentation and bonding. It also discusses the forces involved and common compaction profiles and equations used to describe the process, including the Heckel and Kawakita equations. The document provides an overview of the key concepts and stages in understanding the physics behind tablet production through compression.
Preparation & stability of large & small volume parentralsROHIT
This document discusses parenteral formulations, including definitions, advantages, disadvantages, and classifications. It provides details on the preparation of small volume parenterals and large volume parenterals, including vehicles, buffers, preservatives, and other excipients used. It also covers the stability considerations for parenteral formulations and factors that influence syringeability, injectability, clogging, drainage, resuspendibility, and sedimentation of suspensions.
This document discusses rate-controlled drug delivery systems. It defines sustained release and controlled release, with controlled release implying predictability and reproducibility in drug release kinetics. An ideal controlled delivery system delivers drugs at predetermined rates for specified times. Rate-preprogrammed systems release drugs at pre-set rates through polymer membranes, matrices, or microreservoirs. Activation-modulated systems activate drug release through physical, chemical, or biochemical processes. Examples of activation methods include osmotic pressure, hydrodynamic pressure, vapor pressure, and magnetism.
Dissolution kinetics and dissolutition modeslsagar Aher
This document discusses various mathematical models that can be used to determine the kinetics of drug release from pharmaceutical dosage forms, including zero-order, first-order, Hixon-Crowell, Higuchi, Korsemeyer-Peppas, and Weibull models. It provides the key equations for each model and describes scenarios in which each model is applicable, such as matrix tablets, coated forms, transdermal systems, and others. The models can be used to analyze drug dissolution data and understand the mechanisms of drug release.
This document discusses the formulation and evaluation of microspheres as drug delivery carriers. It defines microspheres as structures made up of one or more polymers in which drug particles are dispersed. Various types of microspheres are described, including bioadhesive, magnetic, floating, and radioactive microspheres. Methods for preparing microspheres include emulsion solvent evaporation, emulsion crosslinking, coacervation, spray drying, and ionic gelation. The document provides formulations for diclofenac-loaded sodium alginate microspheres and ethyl cellulose microspheres. Microspheres are evaluated for assay and in vitro drug release properties. Advantages of microspheres include controlled release, protein stability, drug targeting
In this presentation I have mentioned whatever the possible relevant content required for the Mucoadhesive drug delivery system.
Citation Is done at the end of slide.
Content is up to date & true to my belief.
Thanks & Best Regards.
Anurag Pandey
B.Pharm (FACULTY OF PHARMACY, INVERTIS UNIVERSITY)
M.Pharm (INSTITUTE OF PHARMACY, NIRMA UNIVERSITY)
Email :- anurag.dmk05@gmail.com
This presentation includes the detail information about the physics of tablet compression and compaction, Compression, Effect of friction, distribution of forces, compaction profiles,solubility.
Buccal drug delivery systems provide a promising route for drug administration. They allow drugs to bypass first-pass metabolism by absorbing through the buccal mucosa into the systemic circulation via the facial veins. This presentation discusses buccal tablets, patches, films, gels and ointments as potential dosage forms. Key advantages are ease of administration, termination of therapy, and localization of drug in the oral cavity. However, drugs must not irritate oral tissues and must be stable at buccal pH levels. Evaluation parameters for these systems include residence time, permeation, swelling, release rate and toxicity studies. Some commercial buccal products are used to treat nausea, angina and oral infections.
This document discusses various aspects of drug release and dissolution. It begins by defining the five types of dosage forms that can be characterized by in vitro release, including solid oral dosage forms. It then discusses key concepts like drug products, drug substances, drug release mechanisms for different release types (immediate, delayed, extended), and modified-release dosage forms. The document also provides the definitions and differences between dissolution-controlled systems, diffusion-controlled systems, and combined dissolution-diffusion systems. It introduces mathematical models for drug dissolution like the Noyes-Whitney equation and Hixson-Crowell cube root equation. Finally, it discusses factors that affect drug dissolution and release rates.
mechanism of drug delivery from sr&cr.pptxPawanDhamala1
Modified release drug delivery systems are designed to release drugs at predetermined rates to maintain consistent drug levels over time and minimize side effects. Controlled release formulations deliver drugs locally or systemically at controlled rates for specified periods. Sustained release approaches include matrix systems, reservoir systems, diffusion-controlled systems, and dissolution-controlled systems using polymers, coatings, or osmotic pressure to control drug release rates. Factors like drug properties, dosage, and pharmacokinetics influence release rates from these modified systems.
The document discusses dissolution modeling and its importance in predicting drug release kinetics. It describes 10 common dissolution models including diffusion layer, Danckwert's, interfacial barrier, zero-order, first-order, Higuchi, Korsmeyer-Peppas, Hixson-Crowell, Baker-Lonsdale, and Weibull models. Each model has a unique equation to characterize drug release based on factors like solubility, surface area, diffusion coefficients and particle size. Understanding these models helps optimize formulations and develop in vitro-in vivo correlations to reduce bioequivalence studies.
This document provides an overview of different controlled release polymer systems, including diffusion-controlled systems, solvent-activated systems, and chemically controlled systems. Diffusion-controlled systems use a reservoir or matrix to control the diffusion of a drug. Solvent-activated systems use osmotic pressure or polymer swelling to control drug release. Chemically controlled systems link drugs to polymers or use biodegradable polymers so the drug releases as the polymer breaks down. Magnetically controlled systems can also be used to selectively and controllably release drugs using magnetic fields.
This document summarizes a seminar presentation on microspheres as a novel drug delivery system. It discusses the needs for microspheres, their ideal characteristics, advantages and disadvantages. It also outlines different methods for preparing microspheres, including solvent evaporation, hot melt microencapsulation, solvent extraction, hydrogel microspheres, and spray drying. The document provides details on the materials and evaluation of microspheres and their applications in marketed formulations.
PREFORMULATION CONCEPTS AND OPTIMIZATION IN PHARMACEUTICAL FORMULATIONJayeshRajput7
This document discusses preformulation concepts related to pharmaceutical dosage forms. It covers topics like drug-excipient interactions, kinetics of stability, stability testing, theories of dispersions/pharmaceutical dispersions, and preparation and stability of large and small volume parenterals. Drug-excipient interactions can be physical, chemical, biopharmaceutical, or between excipients. Stability is influenced by factors like temperature, light, and concentration. Kinetics examines the rate of change of drugs over time according to models like zero-order and first-order reactions. Stability testing ensures quality and establishes shelf life. Dispersions are classified by particle size and include emulsions, suspensions, and colloids. Self-
Introduction
Structure
Niosomes Vs. Liposome
Advantages & Disadvantages
Properties of Niosomes
Method of Manufacturing
Evaluation of Niosomes
Applications
Marketed products
Oral sustained and controlled release dosage forms Dr Gajanan Sanap
This document discusses oral sustained and controlled release dosage forms. It begins with an introduction and overview of rationality in designing sustained release drug formulations. It defines sustained release as formulations that continuously release medication over an extended period after a single dose to achieve prolonged therapeutic effects. Controlled release aims to deliver drug at a predetermined rate for a specified time period to maintain constant drug levels. The document outlines the differences between controlled and sustained release. It discusses objectives and advantages of sustained release formulations as well as challenges and factors to consider in design.
POLYMERS IN SOLID STATE, PHARMACEUTICAL APPLICATIONS OF POLYMERS AND RECENT A...Priyanka Modugu
A description on polymers in solid state, solid state properties of polymers, mechanical properties of polymers, heat of crystallization & fusion, thermodynamics of fusion & crystallization, pharmaceutical applications of polymers and recent advances in the use of polymers for drug delivery system
This document summarizes different types of diffusion controlled drug delivery systems. It describes reservoir and matrix devices. Reservoir devices consist of a drug core surrounded by a polymeric membrane, and drug release follows Fick's law of diffusion. Matrix devices involve drug dispersed throughout a polymer matrix, with drug on the surface dissolving first before diffusing out. The document provides the Higuchi equation that describes drug release from a matrix. It notes advantages like zero-order release for reservoir devices and lower risk of leakage for matrix devices, as well as disadvantages like need for removal after drug release. Methods for fabricating these devices like spray drying and coacervation are also summarized.
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.
Transdermal drug delivery system sonamSonam Gandhi
This document summarizes four main types of transdermal drug delivery systems (TDDS): 1) membrane moderated systems, 2) adhesive diffusion controlled systems, 3) matrix dispersion systems, and 4) micro reservoir systems. It provides details on the design and drug release kinetics of each system. In vitro and in vivo evaluation methods are discussed, including diffusion cell studies using animal or human skin to analyze permeation rates of different TDDS formulations.
permeation enhancers by Hemant Chalaune ist M pharm Gaule Jeevan
This document discusses skin as a drug delivery route and permeation enhancers. It begins with an overview of skin structure and properties that create a barrier to drug delivery. It then discusses permeation enhancers, classifying them as chemical or physical and describing examples from each class. The document explains several specific permeation enhancers in depth, including their proposed mechanisms of action, such as disrupting lipid packing or increasing hydration. It concludes that permeation enhancers are crucial components for improving drug bioavailability through the skin.
“It is a process by which a drug leaves a drug product
& is subjected to ADME & eventually becoming
available for pharmacological action.”
It involves the study of drug release rate, dissolution
/diffusion/erosion studies and the study of factors
affecting release rate of the drug.
This document provides an overview of 11 mathematical models that are commonly used to study drug release from pharmaceutical drug delivery systems: 1) Diffusion Model, 2) Zero Order Kinetics Model, 3) First Order Kinetics Model, 4) Higuchi Model, 5) Korsmeyer–Peppas Model, 6) Hixson–Crowell Model, 7) Weibull Model, 8) Baker–Lonsdale Model, 9) Hopfenberg Model, 10) Gompertz model, and 11) Sequential Layer Model. Each model is described in terms of the equations used and their typical applications. The models can help understand drug release mechanisms and optimize drug delivery system design and performance.
Dissolution kinetics and dissolutition modeslsagar Aher
This document discusses various mathematical models that can be used to determine the kinetics of drug release from pharmaceutical dosage forms, including zero-order, first-order, Hixon-Crowell, Higuchi, Korsemeyer-Peppas, and Weibull models. It provides the key equations for each model and describes scenarios in which each model is applicable, such as matrix tablets, coated forms, transdermal systems, and others. The models can be used to analyze drug dissolution data and understand the mechanisms of drug release.
This document discusses the formulation and evaluation of microspheres as drug delivery carriers. It defines microspheres as structures made up of one or more polymers in which drug particles are dispersed. Various types of microspheres are described, including bioadhesive, magnetic, floating, and radioactive microspheres. Methods for preparing microspheres include emulsion solvent evaporation, emulsion crosslinking, coacervation, spray drying, and ionic gelation. The document provides formulations for diclofenac-loaded sodium alginate microspheres and ethyl cellulose microspheres. Microspheres are evaluated for assay and in vitro drug release properties. Advantages of microspheres include controlled release, protein stability, drug targeting
In this presentation I have mentioned whatever the possible relevant content required for the Mucoadhesive drug delivery system.
Citation Is done at the end of slide.
Content is up to date & true to my belief.
Thanks & Best Regards.
Anurag Pandey
B.Pharm (FACULTY OF PHARMACY, INVERTIS UNIVERSITY)
M.Pharm (INSTITUTE OF PHARMACY, NIRMA UNIVERSITY)
Email :- anurag.dmk05@gmail.com
This presentation includes the detail information about the physics of tablet compression and compaction, Compression, Effect of friction, distribution of forces, compaction profiles,solubility.
Buccal drug delivery systems provide a promising route for drug administration. They allow drugs to bypass first-pass metabolism by absorbing through the buccal mucosa into the systemic circulation via the facial veins. This presentation discusses buccal tablets, patches, films, gels and ointments as potential dosage forms. Key advantages are ease of administration, termination of therapy, and localization of drug in the oral cavity. However, drugs must not irritate oral tissues and must be stable at buccal pH levels. Evaluation parameters for these systems include residence time, permeation, swelling, release rate and toxicity studies. Some commercial buccal products are used to treat nausea, angina and oral infections.
This document discusses various aspects of drug release and dissolution. It begins by defining the five types of dosage forms that can be characterized by in vitro release, including solid oral dosage forms. It then discusses key concepts like drug products, drug substances, drug release mechanisms for different release types (immediate, delayed, extended), and modified-release dosage forms. The document also provides the definitions and differences between dissolution-controlled systems, diffusion-controlled systems, and combined dissolution-diffusion systems. It introduces mathematical models for drug dissolution like the Noyes-Whitney equation and Hixson-Crowell cube root equation. Finally, it discusses factors that affect drug dissolution and release rates.
mechanism of drug delivery from sr&cr.pptxPawanDhamala1
Modified release drug delivery systems are designed to release drugs at predetermined rates to maintain consistent drug levels over time and minimize side effects. Controlled release formulations deliver drugs locally or systemically at controlled rates for specified periods. Sustained release approaches include matrix systems, reservoir systems, diffusion-controlled systems, and dissolution-controlled systems using polymers, coatings, or osmotic pressure to control drug release rates. Factors like drug properties, dosage, and pharmacokinetics influence release rates from these modified systems.
The document discusses dissolution modeling and its importance in predicting drug release kinetics. It describes 10 common dissolution models including diffusion layer, Danckwert's, interfacial barrier, zero-order, first-order, Higuchi, Korsmeyer-Peppas, Hixson-Crowell, Baker-Lonsdale, and Weibull models. Each model has a unique equation to characterize drug release based on factors like solubility, surface area, diffusion coefficients and particle size. Understanding these models helps optimize formulations and develop in vitro-in vivo correlations to reduce bioequivalence studies.
This document provides an overview of different controlled release polymer systems, including diffusion-controlled systems, solvent-activated systems, and chemically controlled systems. Diffusion-controlled systems use a reservoir or matrix to control the diffusion of a drug. Solvent-activated systems use osmotic pressure or polymer swelling to control drug release. Chemically controlled systems link drugs to polymers or use biodegradable polymers so the drug releases as the polymer breaks down. Magnetically controlled systems can also be used to selectively and controllably release drugs using magnetic fields.
This document summarizes a seminar presentation on microspheres as a novel drug delivery system. It discusses the needs for microspheres, their ideal characteristics, advantages and disadvantages. It also outlines different methods for preparing microspheres, including solvent evaporation, hot melt microencapsulation, solvent extraction, hydrogel microspheres, and spray drying. The document provides details on the materials and evaluation of microspheres and their applications in marketed formulations.
PREFORMULATION CONCEPTS AND OPTIMIZATION IN PHARMACEUTICAL FORMULATIONJayeshRajput7
This document discusses preformulation concepts related to pharmaceutical dosage forms. It covers topics like drug-excipient interactions, kinetics of stability, stability testing, theories of dispersions/pharmaceutical dispersions, and preparation and stability of large and small volume parenterals. Drug-excipient interactions can be physical, chemical, biopharmaceutical, or between excipients. Stability is influenced by factors like temperature, light, and concentration. Kinetics examines the rate of change of drugs over time according to models like zero-order and first-order reactions. Stability testing ensures quality and establishes shelf life. Dispersions are classified by particle size and include emulsions, suspensions, and colloids. Self-
Introduction
Structure
Niosomes Vs. Liposome
Advantages & Disadvantages
Properties of Niosomes
Method of Manufacturing
Evaluation of Niosomes
Applications
Marketed products
Oral sustained and controlled release dosage forms Dr Gajanan Sanap
This document discusses oral sustained and controlled release dosage forms. It begins with an introduction and overview of rationality in designing sustained release drug formulations. It defines sustained release as formulations that continuously release medication over an extended period after a single dose to achieve prolonged therapeutic effects. Controlled release aims to deliver drug at a predetermined rate for a specified time period to maintain constant drug levels. The document outlines the differences between controlled and sustained release. It discusses objectives and advantages of sustained release formulations as well as challenges and factors to consider in design.
POLYMERS IN SOLID STATE, PHARMACEUTICAL APPLICATIONS OF POLYMERS AND RECENT A...Priyanka Modugu
A description on polymers in solid state, solid state properties of polymers, mechanical properties of polymers, heat of crystallization & fusion, thermodynamics of fusion & crystallization, pharmaceutical applications of polymers and recent advances in the use of polymers for drug delivery system
This document summarizes different types of diffusion controlled drug delivery systems. It describes reservoir and matrix devices. Reservoir devices consist of a drug core surrounded by a polymeric membrane, and drug release follows Fick's law of diffusion. Matrix devices involve drug dispersed throughout a polymer matrix, with drug on the surface dissolving first before diffusing out. The document provides the Higuchi equation that describes drug release from a matrix. It notes advantages like zero-order release for reservoir devices and lower risk of leakage for matrix devices, as well as disadvantages like need for removal after drug release. Methods for fabricating these devices like spray drying and coacervation are also summarized.
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.
Transdermal drug delivery system sonamSonam Gandhi
This document summarizes four main types of transdermal drug delivery systems (TDDS): 1) membrane moderated systems, 2) adhesive diffusion controlled systems, 3) matrix dispersion systems, and 4) micro reservoir systems. It provides details on the design and drug release kinetics of each system. In vitro and in vivo evaluation methods are discussed, including diffusion cell studies using animal or human skin to analyze permeation rates of different TDDS formulations.
permeation enhancers by Hemant Chalaune ist M pharm Gaule Jeevan
This document discusses skin as a drug delivery route and permeation enhancers. It begins with an overview of skin structure and properties that create a barrier to drug delivery. It then discusses permeation enhancers, classifying them as chemical or physical and describing examples from each class. The document explains several specific permeation enhancers in depth, including their proposed mechanisms of action, such as disrupting lipid packing or increasing hydration. It concludes that permeation enhancers are crucial components for improving drug bioavailability through the skin.
“It is a process by which a drug leaves a drug product
& is subjected to ADME & eventually becoming
available for pharmacological action.”
It involves the study of drug release rate, dissolution
/diffusion/erosion studies and the study of factors
affecting release rate of the drug.
This document provides an overview of 11 mathematical models that are commonly used to study drug release from pharmaceutical drug delivery systems: 1) Diffusion Model, 2) Zero Order Kinetics Model, 3) First Order Kinetics Model, 4) Higuchi Model, 5) Korsmeyer–Peppas Model, 6) Hixson–Crowell Model, 7) Weibull Model, 8) Baker–Lonsdale Model, 9) Hopfenberg Model, 10) Gompertz model, and 11) Sequential Layer Model. Each model is described in terms of the equations used and their typical applications. The models can help understand drug release mechanisms and optimize drug delivery system design and performance.
Dissolution: how to calculate dissolution calculation in excel sheetSagar Savale
The document describes how to calculate drug dissolution in an Excel sheet. It involves creating a standard calibration curve by measuring the absorbance of drug solutions with known concentrations. An equation is generated from the calibration curve graph that relates absorbance to concentration. This equation is then used to calculate the concentration of test solutions from their absorbance readings over time during a dissolution test. The concentrations are used to determine the percentage of drug dissolved at each time point.
The document discusses comparison of dissolution profiles through different methods and establishing an IVIVC (in vitro-in vivo correlation). It provides definitions of dissolution profile and objectives of comparing profiles. Various methods for comparing profiles are described, including graphical, statistical, and model-dependent/independent methods. Key factors for determining similarity between dissolution profiles using statistical methods like difference factor and similarity factor are outlined. The importance of developing an IVIVC to reduce costs and the need for bioavailability studies is also mentioned. A research article comparing different brands of metformin tablets using tests like dissolution rate, drug content and disintegration is briefly summarized.
The document summarizes a study evaluating the dissolution behavior of 500mg Paracetamol tablets according to USP guidelines using the paddle method. The study found that 126.2% of the Paracetamol dissolved within 30 minutes, meeting the USP and BP standards of dissolving at least 80% within 30 minutes. The paddle apparatus and UV spectrophotometry were used to test six tablets and obtain dissolution profiles. The results indicate the tested Paracetamol tablets meet pharmacopeial standards for dissolution.
DISSOLUTION
Dissolution is defined as a process in which a solid substance solubilises in a given solvent.
(i.e. mass transfer from the solid surface to the liquid phase.)
Three Theories:
Diffusion layer model / Film theory
Danckwert’s model / Penetration or Surface renewal theory
Interfacial barrier model / Double barrier or Limited solvation theory
Dissolution, factors affecting drug dissolution, methods to evaluate dissolution, advantages and disadvantages, recent approaches--these are the topics covered in this presentation.
This document discusses different types of controlled release drug delivery systems. It describes rate preprogrammed systems which release drugs at predetermined rates, including polymer membrane and matrix diffusion systems. It also covers feedback regulated systems where drug release is activated by biological triggers, including bioerosion, bioresponsive, and self-regulating systems. The advantages of controlled release include improved patient convenience and safety, while disadvantages can include reduced systemic availability and difficulty retrieving drugs in emergencies.
This document discusses targeted drug delivery systems. It defines targeted drug delivery as selectively delivering medication to its site of action to increase concentration in tissues of interest while reducing it in other tissues, improving efficacy and reducing side effects. The document outlines various strategies for targeted delivery including passive, active, ligand-mediated and physical targeting. It also describes several types of targeted delivery systems including liposomes, dendrimers, nanotubes, nanoshells and others. The goal is to achieve the desired pharmacological response at selected sites with minimal side effects.
The document summarizes guidelines from JNC 8 (2014) on the management of hypertension. It provides 3 key recommendations from JNC 8:
1) Treatment should begin for general population aged ≥60 years with SBP ≥150 mmHg or DBP ≥90 mmHg, and for those <60 years with SBP ≥140 mmHg or DBP ≥90 mmHg.
2) The treatment goal for non-diabetic, non-CKD patients is SBP <150 mmHg and DBP <90 mmHg. Lower goals may apply if no adverse effects.
3) Initial treatment should include ACE inhibitors, angiotensin receptor blockers, calcium channel blockers or thiaz
This document discusses different methods for approximating zero-order and first-order drug release from sustained release drug formulations, including encapsulated beads or granules, tablet formulations, and approaches based on modifying the drug's properties. It describes factors that influence drug release rates such as solubility, absorption rates, and enzymatic metabolism and provides examples of complexation, adsorbates, and prodrugs for achieving sustained release. In vitro drug release testing methods aim to simulate drug passage through the gastrointestinal tract and ensure batch uniformity.
This document discusses the challenges of developing multicompartment drug delivery systems. It outlines three main challenges: 1) defining the architecture so aggregates have distinct containers and self-terminate, 2) enabling defined communication between compartments, and 3) achieving defined encapsulation of drugs. DNA-mediated self-assembly may help address the first challenge of creating well-defined, self-assembled and self-terminated aggregates. Future work is still needed to solve challenges around compartment communication and encapsulation to realize the benefits of multicompartment drug delivery systems.
Prodrugs are inactive derivatives of active drug molecules that undergo biotransformation in the body to release the active drug. They are designed to improve drug solubility, stability, absorption, distribution, and reduce toxicity and side effects. Prodrugs can be classified as carrier-linked or bioprecursor types. The carrier-linked type attaches the active drug to an inert carrier molecule through a metabolically labile bond. Bioprecursor prodrugs rely on metabolic activation like oxidation or phosphorylation to release the active drug. Key steps in prodrug design involve identifying delivery problems and selecting a carrier to impart the desired properties while releasing the active drug in the target area. Common applications of prodrugs include targeting the brain
This document summarizes current management of hypertension. It begins by stating the high worldwide prevalence of hypertension and its attributable risk for death. It then discusses definitions and classifications of hypertension according to guidelines. Target blood pressure goals for optimal management are outlined, along with evaluating for target organ damage. The importance of lifestyle modifications and pharmacological therapy to reduce cardiovascular events is emphasized.
The document discusses various approaches to designing implantable drug delivery systems. It describes systems that use diffusion processes like polymer membrane permeation or matrix diffusion to control drug release. It also covers systems that use activation processes like osmotic pressure, vapor pressure, hydration or hydrolysis to control drug release. Finally, it mentions systems that use feedback regulated mechanisms, where drug release is activated and controlled by the concentration of biochemical substances detected at the implant site.
This document provides an overview of fundamentals of modified release formulations. It discusses different mechanisms for controlling drug release including diffusion controlled, dissolution controlled, and erosion controlled systems. It describes key aspects of reservoir and matrix devices for diffusion controlled release as well as encapsulation and matrix systems for dissolution controlled release. The document also covers erosion controlled delivery, hybrid systems, relevant mathematical models, and some examples of marketed modified release products.
This document discusses approaches to controlled release oral drug delivery systems using hydrodynamically balanced systems. It describes various gastrointestinal anatomy and physiology factors that influence gastric retention time such as size, density, and food intake. Several mechanistic approaches to achieve prolonged gastric retention are outlined, including high-density systems, bioadhesive systems, swelling and expanding systems, magnetic systems, superporous hydrogels, and floating systems. Floating drug delivery systems that form rafts or generate gas are described as important approaches to obtain sufficient drug bioavailability through gastric retention.
Prodrug approaches for cns delivery ppt finished copyAtul Thakur
This document discusses prodrug approaches for central nervous system (CNS) drug delivery. It covers various prodrug concepts including increasing lipophilicity to enhance passive diffusion across the blood-brain barrier (BBB), utilizing endogenous transporters for carrier-mediated delivery, overcoming efflux transport, and antibody or gene-directed targeted therapies. The key roles of prodrug bioconversion kinetics and competing elimination processes are also addressed. Overall, the document provides an overview of rational chemistry and biology-based strategies to improve brain delivery of CNS therapeutics.
An emulsion is a mixture of two immiscible liquids, where one liquid is dispersed as globules in the other. There are two types: oil-in-water (O/W) and water-in-oil (W/O). Emulsions have advantages like masking unpleasant tastes and sustained drug release, but are thermodynamically unstable with a short shelf life. Emulsions contain a dispersed internal phase and a continuous external phase, and emulsifying agents are used to stabilize the emulsion by reducing interfacial tension at the boundary between the two liquids.
This document discusses methods for comparing drug dissolution profiles, which provide information about how completely and quickly an active pharmaceutical ingredient is released from its dosage form. Graphical and statistical methods are described for directly comparing dissolution curves. Model-dependent approaches apply kinetic models like zero-order, first-order, and Higuchi models to the data. Model-independent methods calculate similarity factors f1 and f2 that provide single values for comparing profiles. Comparing dissolution profiles is important for evaluating drug release and bioequivalence of pharmaceutical formulations.
This document provides an overview of fundamental concepts in controlled drug delivery systems. It discusses factors that influence the design of controlled release systems such as solubility, partition coefficient, molecular size, dose size, and drug stability. It also covers classifications of controlled release systems including dissolution controlled, diffusion controlled, and chemically controlled systems. The document concludes with a discussion of mathematical models used to evaluate the kinetics and mechanisms of drug release, including zero-order, first-order, Hixson-Crowell, Higuchi, and Korsmeyer-Peppas models.
This presentation discusses the correlation of dissolution with In-vitro In-vivo correlation, Effect of Selection of Dissolution Apparatus and Dissolution Medium on IVIVC, BCS classification and levels of IVIVC.
This document discusses different types of rate controlled drug delivery systems. It begins by introducing controlled release drug delivery and distinguishing it from sustained release. It then classifies controlled release systems into three main categories: rate programmed, activation modulated, and feedback regulated systems. Within each category it describes several examples of systems, identifying how drug release is controlled in each case. Key factors that can affect controlled release are also listed. The document aims to provide an overview of controlled drug delivery technologies with classifications and examples.
Group 9 Biopharmaceutical & Pharmacokinetic Considerations.pptxfariahqaiser1
The document discusses considerations for designing controlled release drug delivery systems. It describes four main mechanisms for controlling drug release: dissolution control, diffusion control, osmotic pressure control, and ion exchange control. Factors that influence the design of controlled release systems include biopharmaceutical characteristics of the drug like molecular weight, solubility, partition coefficient, and pKa, as well as pharmacokinetic characteristics. The biopharmaceutical properties that are most important to consider are molecular size, diffusion coefficient, aqueous solubility, partition coefficient, and ionization state of the drug at physiological pH levels. Controlled release systems aim to optimize how the body processes a drug to maximize its effects.
This document provides an overview of osmotically controlled drug delivery systems. It discusses the principles of osmosis that these systems utilize. Key components include a drug, osmotic agent, and semipermeable membrane. Factors that can affect the drug release rate include drug solubility, osmotic pressure, membrane characteristics, and orifice size. Various types of osmotic pumps are classified and described, including oral and implantable versions. Commercial applications and evaluation methods are also mentioned.
These systems are capable of controlling the rate of drug delivery, sustaining the duration of therapeutic efficacy, and/or targeting the delivery of drug to a tissue. Depending upon the technical sophistication, these rate-control drug delivery systems can be classified into three major categories: (i) pre-programmed drug delivery, (ii) activation-controlled drug delivery, and (iii) feedback-regulated drug delivery.
Controlled Release Oral Drug Delivery System
Controlled drug delivery is one which delivers the drug at a predetermined rate, for locally or systemically, for a specified period of time.
Controlled Release Drug Delivery Systems - Types, Methods and ApplicationsSuraj Choudhary
This document discusses factors affecting the design of controlled release drug delivery systems (CRDDS). It outlines several key considerations for CRDDS design including selection of the drug candidate, medical and biological rationale, and physicochemical properties. It also discusses important physicochemical factors such as solubility, partition coefficient, molecular size and diffusivity, dose size, complexation, ionization constant, drug stability, and protein binding that influence CRDDS design. Finally, it briefly describes dissolution-controlled and diffusion-controlled release approaches for developing CRDDS.
This document summarizes key concepts related to diffusion, dissolution, and pharmacokinetic parameters. It defines diffusion as the spontaneous migration of molecules from high to low concentration regions driven by Brownian motion. Fick's laws describe the rate of diffusion being proportional to the concentration gradient. Dissolution is defined as a solid solute dissolving in a solvent to form a solution. Several parameters influence dissolution rate including surface area, diffusion coefficient, and concentration gradient. Pharmacokinetics describes the absorption, distribution, metabolism, and excretion of drugs and key parameters include Cmax, Tmax, and AUC which describe the concentration of drugs in plasma over time.
This document provides information on factors affecting the design of controlled release drug delivery systems (CRDDS). It discusses selection of drug candidates, medical and biological rationales, physicochemical properties, in vitro and in vivo evaluation, and regulatory considerations. Dissolution-controlled and diffusion-controlled delivery systems are described. Key factors like solubility, partition coefficient, molecular size, dose size, and stability are explained. Different approaches for controlled release like matrix systems, encapsulation, reservoir devices are summarized.
COMPOUNDS THAT CANNOT BE FORMULATED AS CONTROLLED RELEASE SYSTEMArunpandiyan59
This document discusses compounds that are unsuitable for controlled release drug delivery systems. It provides terminology for different types of modified release products and discusses advantages and disadvantages of controlled release forms. Key factors that make drugs unsuitable for controlled release include short or long elimination half-lives, narrow therapeutic indices, poor absorption, extensive metabolism, variable bioavailability, and absorption issues related to solubility, stability, molecular size, and transport mechanisms. The document also discusses physiological factors such as distribution, metabolism, and protein binding that impact controlled release drug design.
This document discusses solubility and dissolution of solids in liquids, which are important processes in pharmaceutical solutions. It describes dissolution as a process where a substance goes into solution. Solubility is defined as the capacity of a solute to dissolve in a pure solvent. The document then discusses key steps in the dissolution process including removal of drug molecules from the solid state, formation of solvent cavities, and accommodation of drug molecules into the cavities. It presents the Noyes-Whitney equation, which describes dissolution rate in terms of surface area, concentration gradient, and diffusion coefficient. Finally, it notes that quality control dissolution testing is required by the FDA to ensure batch-to-batch uniformity of pharmaceutical formulations.
This document discusses polymer membrane permeation controlled drug delivery systems. It defines controlled release as delivering drugs at predetermined rates over long periods from a single dose. Controlled release implies predictable and reproducible drug release kinetics. A key example is a system where a drug reservoir is covered by a rate-controlling polymeric membrane. The membrane thickness and drug properties determine the release rate. Applications include the Norplant implant and Ocusert ocular insert.
This document discusses various approaches to developing implantable drug delivery systems, including controlled drug delivery via diffusion, activation processes, and feedback regulation. It describes systems that use polymer membranes, matrices, microreservoirs, and hybrid designs to control drug release rates. Activation methods include osmotic pressure, vapor pressure, magnetism, hydration, and hydrolysis. Feedback systems can be regulated by bioerosion and bioresponses to biochemical factors. The document provides examples of implantable systems and discusses how drug and system properties influence release kinetics.
Concept and systems of design for rate controlled drug delivery systemEknath Babu T.B.
This document describes different types of rate-controlled drug delivery systems. It discusses rate preprogrammed systems which release drug at a predetermined rate, including polymer membrane, polymer matrix, and microreservoir systems. It also covers activation-modulated systems where drug release is activated by physical, chemical, or biochemical processes like osmotic pressure. The key advantages of controlled drug delivery systems are maintaining consistent drug levels, reducing dosing frequency, and improving patient convenience and compliance.
Rate Controlled Drug Delivery Systems, Activation Modulated Drug Delivery Systems, Mechanically activated, pH activated, Enzyme activated, Osmotic activated Drug Delivery Systems, Feedback regulated Drug Delivery Systems systems are discussed here.
This document discusses rate-controlled drug delivery systems. It begins by classifying these systems into four categories: rate pre-programmed, activation modulated, feedback regulated, and site targeting. Rate pre-programmed systems include polymer membrane, polymer matrix, and microreservoir designs. Activation modulated systems use physical, chemical, or biochemical processes to activate drug release, such as osmotic pressure, pH, or enzymes. Feedback regulated systems sense physiological parameters and release drug accordingly. Site targeting systems deliver drugs specifically to certain tissues. The document provides examples like transdermal patches and implants to illustrate these concepts.
The document provides an overview of drug dissolution including:
- Definitions of dissolution rate and intrinsic dissolution rate.
- Theories of drug dissolution including the diffusion layer model, Danckwert's model, and the interfacial barrier model.
- Factors that affect drug dissolution related to the physicochemical properties of drugs, drug product formulation, processing factors, dissolution apparatus and test parameters.
- Importance and applications of drug dissolution testing in product development, quality assurance, stability assessment, and biowaivers.
This document discusses various parameters used to characterize drug release from pharmaceutical formulations. It describes diffusion parameters defined by Higuchi's equation and plots. Dissolution parameters like the effects of agitation, pH, temperature, and medium properties are outlined. Pharmacokinetic parameters including Cmax, Tmax, and AUC are defined. The Heckel equation is presented as a method to analyze powder compaction. Similarity factors f1 and f2 are introduced to compare dissolution profiles. The Higuchi and Korsmeyer-Peppas models for drug release are presented.
Similar to Release kinetics By subhakanta Dhal (20)
5-hydroxytryptamine or 5-HT or Serotonin is a neurotransmitter that serves a range of roles in the human body. It is sometimes referred to as the happy chemical since it promotes overall well-being and happiness.
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The skin is the largest organ and its health plays a vital role among the other sense organs. The skin concerns like acne breakout, psoriasis, or anything similar along the lines, finding a qualified and experienced dermatologist becomes paramount.
10 Benefits an EPCR Software should Bring to EMS Organizations Traumasoft LLC
The benefits of an ePCR solution should extend to the whole EMS organization, not just certain groups of people or certain departments. It should provide more than just a form for entering and a database for storing information. It should also include a workflow of how information is communicated, used and stored across the entire organization.
Histololgy of Female Reproductive System.pptxAyeshaZaid1
Dive into an in-depth exploration of the histological structure of female reproductive system with this comprehensive lecture. Presented by Dr. Ayesha Irfan, Assistant Professor of Anatomy, this presentation covers the Gross anatomy and functional histology of the female reproductive organs. Ideal for students, educators, and anyone interested in medical science, this lecture provides clear explanations, detailed diagrams, and valuable insights into female reproductive system. Enhance your knowledge and understanding of this essential aspect of human biology.
Adhd Medication Shortage Uk - trinexpharmacy.comreignlana06
The UK is currently facing a Adhd Medication Shortage Uk, which has left many patients and their families grappling with uncertainty and frustration. ADHD, or Attention Deficit Hyperactivity Disorder, is a chronic condition that requires consistent medication to manage effectively. This shortage has highlighted the critical role these medications play in the daily lives of those affected by ADHD. Contact : +1 (747) 209 – 3649 E-mail : sales@trinexpharmacy.com
Mercurius is named after the roman god mercurius, the god of trade and science. The planet mercurius is named after the same god. Mercurius is sometimes called hydrargyrum, means ‘watery silver’. Its shine and colour are very similar to silver, but mercury is a fluid at room temperatures. The name quick silver is a translation of hydrargyrum, where the word quick describes its tendency to scatter away in all directions.
The droplets have a tendency to conglomerate to one big mass, but on being shaken they fall apart into countless little droplets again. It is used to ignite explosives, like mercury fulminate, the explosive character is one of its general themes.
Cell Therapy Expansion and Challenges in Autoimmune DiseaseHealth Advances
There is increasing confidence that cell therapies will soon play a role in the treatment of autoimmune disorders, but the extent of this impact remains to be seen. Early readouts on autologous CAR-Ts in lupus are encouraging, but manufacturing and cost limitations are likely to restrict access to highly refractory patients. Allogeneic CAR-Ts have the potential to broaden access to earlier lines of treatment due to their inherent cost benefits, however they will need to demonstrate comparable or improved efficacy to established modalities.
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8 Surprising Reasons To Meditate 40 Minutes A Day That Can Change Your Life.pptxHolistified Wellness
We’re talking about Vedic Meditation, a form of meditation that has been around for at least 5,000 years. Back then, the people who lived in the Indus Valley, now known as India and Pakistan, practised meditation as a fundamental part of daily life. This knowledge that has given us yoga and Ayurveda, was known as Veda, hence the name Vedic. And though there are some written records, the practice has been passed down verbally from generation to generation.
2. 1. To study prediction of in vitro release.
2. To study prediction release kinetics of excipients .
3. To support data of IVIVC.
4. Study helps in pharmacokinetic model.
5. To correlate pharmacokinetic parameter.
6. To study mechanism of enzyme as well as receptor
kinetics.
7. To study acclerated stability kinetic model.
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Objective of Kinetics
3. Release Rates : IR, SR, CR
Release Profiles : Dissolution Models
Release Times : Rapid onset, Delayed Release etc
Release Sites : One or More Sites of GI Tract
Design of Release Controlling
Formulation
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4. a
Dissolution Rate
Modified Noyes and Whitney Equation:
Diffusion Rate Constant = D
Surface Area = S
Volume of the Dissolution Media = v
Thickness of the Saturated Layer = h
Concentration of the API at Saturation = Cs
Dissolution Rate Constant = k
Concentration of the Bulk Solution = Ct
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6. Drug Release Mechanisms
• Wetting of the system’s surface with water.
• Water penetration into the device (e.g., via pores and/or through
continuous polymeric networks).
• Phase transitions of (polymeric) excipients (e.g., glassy-to rubbery-phase
transitions).
• Drug and Excipient dissolution.
• Hindrance of rapid and complete drug and Excipient dissolution due to
limited solubility and/or dissolution rates under the given conditions.
• Drug and/or Excipient degradation.
• Dissolution and/or precipitation of degradation products.
• Creation of water-filled pores.
• Pore closing due to polymer swelling.
• Creation of significant hydrostatic pressure within the delivery system,
e.g. in the case of coated dosage forms.
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7. • Creation of cracks within release rate limiting membranes.
• Creation of acidic or basic microenvironments within the dosage forms
due to degradation products.
• Changes in the rate of drug and/or Excipient degradation rate due to
changes in the microenvironmental pH.
• Physical drug-Excipient interactions (e.g., ion–ion attraction/repulsion
and Van der Waals forces), which might significantly vary with time and
position due to changes in the microenvironmental conditions, such as
the pH, presence of counter ions and ionic strength.
• Changes in drug and/or Excipient solubility due to altered micro
environmental conditions (e.g., pH, ionic strength, etc.).
• Diffusion of drugs and/or excipients out of the dosage form with
potentially time- and/or position-dependent diffusion coefficients.
Drug Release Mechanisms Cont…..
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8. The Mechanistic Realistic Theories
.
A mechanistic realistic mathematical model is based on equations that
describe real phenomena, e.g. mass transport by diffusion, dissolution of
drug and/or Excipient particles, and/or the transition of a polymer from
the glassy to the rubbery .
These equations form the basis of the mathematical theory,Often partial
differential equations are involved.
If the amount of drug released or release rate can be separated from all
other variables and parameters on one side of the equation, the solution
is called explicit and the effects of the considered formulation and
processing parameters can be (more or less) directly be seen. if it is not
possible to separate the amount/rate of drug release from the other
variables and parameters, only a so-called implicit solution can be derived,
and the effects of the formulation and processing parameters is often less
direct.
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9. The Mechanistic Realistic Theories
.
Based on the physical or chemical characteristics of polymer, drug
release mechanism from a polymer matrix can be categorized in
accordance to three main processes (systems).
Drug diffusion from the non-degraded polymer (diffusion-controlled
system).
Enhanced drug diffusion due to polymer swelling (swelling-
controlled system).
Drug release due to polymer degradation and erosion (erosion-
controlled system).
Drug release may be due to dissolution based.
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10. Diffusion - Controlled System
The boundary conditions are influenced by the mass transfer process
at the surface and the volume of the surrounding system. Based on
these conditions, there are three main cases which are commonly
considered
For diffusion-controlled drug release profile is obtained by solving
Fick's second law of diffusion subject to appropriate boundary
conditions.
For one-dimensional drug release from a Drug system, the second
Flick's law of diffusion is where D and C are the diffusion coefficient
and drug concentration in the polymer matrix.
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11. a
Diffusion - Controlled System Cont.…
The mass transfer resistance at the surface is negligible and the surrounding
release medium is infinitely large (perfect sink condition), implying that the
concentration on the surface of the matrix (Cs) is constant
(Cs=K .Cb=constant at r=R). Here, Cb is the drug concentration in
surrounding bulk medium and K is the drug partition coefficient between the
matrix and bulk medium.
The mass transfer resistance at the surface is finite and the surrounding
volume is in perfect sink condition, implying that the concentration of the
surrounding system is constant, but the convective mass transfer coefficient
(h) will determine the surface concentration.
The surrounding system is a well-stirred finite volume. This implies that the
concentration of the surrounding system changes with time. The surface
resistance may or may not be negligible.
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12. a
Diffusion - Controlled System Cont.…
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Schematic illustration of cross-section of drug-system of (a) reservoir system,
(b) dissolved drug system, and(c) dispersed drug system. In reservoir system,
drug is confined by a spherical shell of outer radius R and inner radius Ri;
therefore, the drug must diffuse through a polymer layer of thickness (R−Ri).
In dissolved drug system, drug is dissolved uniformly at loading concentration
C0 in the polymeric matrix. In dispersed drug system, the radius of inner
interface between “core” (non-diffusing) and matrix (diffusing) regions, r′(t),
shrinks with time. The “core” region is assumed to be at drug loading
concentration C0.
13. Based on the Above figure region where the drug diffusion primarily takes place, the
diffusion-controlled system can be further categorized to reservoir and matrix systems.
Reservoir Systems
The reservoir system consists of a drug reservoir surrounded by the polymer matrix shell.
The reservoir model is the simplest model of a solute of drug released from a sphere
It assumes that drug is confined by a spherical shell of outer radius R and inner radius Ri;
thus, the drug must diffuse through a layer of thickness (R−Ri).
Matrix System
In matrix system, the drug is incorporated in the polymer matrix in either dissolved or
dispersed condition.
Mathematical models for matrix systems are often valid for drug devices developed based on
no biodegradable polymers.
In these models, the drug is commonly assumed to be uniformly distributed inside the non-
biodegradable polymer matrix. There are two possible cases, which are (i) the initial drug
loading is lower than the solubility of the drug inside the polymer matrix (C0bCs), which
implies a dissolved drug system, and (ii) the initial drug loading is higher than the solubility
of the drug inside the polymer matrix (C0NCs), which implies a dispersed drug system.
Diffusion - Controlled System Cont.…
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14. a
Swelling - Controlled Systems
The idea of using a swelling polymer is to provide more control over the release of drug,
especially when its diffusivity in polymer is very low.
For this purpose, a swell able is commonly made using a hydrophilic polymer so that water
is able to imbibe into the polymer matrix and cause polymer disentanglement..
The imbibing water into the polymer matrix decreases the polymer concentration and
changes the level of polymer disentanglement.
The polymer matrix disentanglement also leads to matrix swelling that results in the
rubbery (gel layer) region, in which there is an “enhanced diffusion” where drug mobility
increases.
The polymer will also dissolve at the interface when the entanglement is weak since
polymer concentration is very low.
Thus, in this system, the deviation from Fickian model is observe when the drug release is
not only controlled by the diffusion of the drug inside the matrix, but also by the polymer
matrix disentanglement and dissolution process.
For swelling-controlled system, the hydrophilic polymer is susceptible to swelling as water
tends to penetrate and relax the polymer matrix. In this case, the composition of the
hydrophilic polymer will determine the extent of swelling.
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15. Typical Hydrophilic Polymers-Hydroxypropyl Methylcellulose (HPMC), Poly
(hydroxyethyl Methacrylate) or Pol (HEMA), and Poly (Vinyl Alcohol) (PVA).
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Swelling - Controlled Systems Cont...
16. a
Lee and Peppas Model
The swelling occurs to achieve thermodynamics equilibrium when water penetrates cross
linked region inside the polymer matrix due to a water concentration gradient.
As water penetrates and swelling takes place, a transformation of polymer from a glassy to
rubbery state occurs and the dimension of the matrix increases.
This change of state basically creates a gel layer of rubbery region for the drug to diffuse,
in which the drug diffusivity increases substantially.
Therefore, during the swelling, two different states, namely the glassy core and gel layer
(rubbery), exist in the polymer matrix.
Here, the concept of two moving fronts, namely the glassy– rubbery front (R) and the
rubbery–solvent front (S), is introduced. Initially during swelling, front R moves inwards,
whereas front S moves outward. When the polymer at interface S reaches its
thermodynamic equilibrium with the surrounding medium, interface S will start dissolving
and, therefore, front S moves inwards.
Both fronts will move inwards until the front R diminishes as the glassy core disappears.
Subsequently at later time, only the rubbery region is present and dissolution at interface S
eventually controls the shrinking process
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Swelling - Controlled Systems Cont...
17. a
Schematic illustration of one-dimensional swelling process due to solvent diffusion and
polymer dissolution as proposed by Lee (a) initial thickness of the carrier, (b) early-time
swelling when there are increasing position of the rubbery/solvent interface (S) and
decreasing position of the glassy/rubbery interface (R), (c) late-time swelling when
there are decreases of both interface S and R positions, and (d) final dissolution process
when the slab only comprises rubbery region with the decrease of interface S .
Swelling - Controlled Systems Cont...
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18. THE erosion kinetics can be altered by modifying copolymer composition or the
degree of crystallinIty as crystalline and amorphous polymers erode at different rates.
It is important to distinguish the two different terms commonly used in describing the
polymer erosion phenomena, namely degradation and erosion.
In a simplistic point of view, degradation refers to the polymer chain/bond
cleavage/scission reaction (chemical process), whereas the erosion designates the loss of
polymer material in either monomers or oligomers (chemical and physical process).
The erosion may consist of several chemical and physical steps, including degradation.
Since erosion is a more general term to capture the overall mechanism of the bio
erodible system, this section will mainly utilize the term erosion.
The term of degradation will still be used when specific degradation processes, e.g.
polymer backbone cleavage and autocatalytic process, are involved in the model.
Gel permeation chromatography (GPC) can be used to monitor the polymer molecular
weight changes during the drug release and erosion.
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Erosion - Controlled Systems
20. There are two ideal scenarios for polymer erosion, namely surface (heterogeneous) and
bulk (homogeneous) erosions
In bulk erosion, the system has a constant diameter size and external fluid is allowed to
penetrate into the during which erosion of the polymer occurs.
On the other hand, in surface erosion, the system has an evolving shrinking diameter as
the erosion of the polymer takes place at the external matrix boundary.
surface erosion polymer-- (1,3-bis-p-carboxyphenoxypropane-co-sebacic acid) (p(CPP-
SA)) and poly(1,6-bis-p-carboxyphenoxyhexane- co-sebacic acid) (p(CPH-SA)).
Bulk erosion polymer-- poly(lactic acid) (PLA), poly(lacticco- glycolic acid) (PLGA),
and poly(ε caprolactone)( PCL).
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Erosion - Controlled Systems Cont…
22. Release Kinetics
Release Kinetics:
Data obtained from in-vitro release studies were fitted to various kinetics
models to find out the mechanism of drug release Kinetics models used for in-
vitro drug release from are
Zero order release kinetic model
First order release kinetic model [1897]
Hixon-crowell model[1931]
Higuichi model [T. Higuichi 1963 & W. I Higuichi 1967]
Kosysmer-peppes model.
Other Model- Weibull model, Hopfenberg model, Gompertz, sequential
layer, Empirical models, reciprocal powered time model
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23. a
Zero Order Kinetics
According to this model, under standard condition of temperature and agitation, the dissolution
medium, the dissolution rate model can be described by the equation.
DQ/dt=K0
Or, in an integrated form
q= K0t
Where, q = Amount of drug released per unit surface area
K0 = Zero order release rate constant
T= Time
A plot ‘q’ vs. t’ gives a straight line.
CONDITION
Drug dissolution from pharmaceutical dosage forms that do not disaggregate and release the drug
slowly (assuming that area does not change and no equilibrium conditions are obtained).
APPLICATION
modified release pharmaceutical as in the case of some transdermal systems as well as matrix tablets
with low soluble drugs, coated forms, osmotic systems, etc. for prolonged action.
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24. First Order Release Kinetics
(Noyes Whitney’s Equation)
According to Noyes Whitney, under standard condition of agitation and temperature, the
dissolution rate process for solids can be described by the equation.
Dq/dt = K1 (Cs –Ct)
Under sink condition, i.e. when Ct<0. 15Cs, the equation becomes,
Dq/dt = K1Cs
Or, in an integrated form
In q0/q = K1t
Where, q= Amount of drug release per unit surface area
K1 = first order release rate constant
Q0 = Initial amount
Cs = saturation solubility
Ct = Concentration at time‘t’
A plot of log % remaining to be released vs. ‘time’ gives a straight line with a negative
slope.
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25. APPLICATION
The pharmaceutical dosage forms, such as those containing water-soluble
drugs in porous matrices release getting: the drug in a way that is
proportional to the amount of drug remaining in its interior . in such
way, that the amount of drug released by unit of time diminish.
First Order Release Kinetics
(Noyes Whitney’s Equation) Cont….
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26. Hixson – Crowell Model Kinetics
As solid dissolved the surface area S changes with time. The Hixon Crowell cube root
equation for dissolution kinetics is based on the assumption that:
Dissolution occurs normal to the surface of soluble particles.
Agitation is on the overall exposed surface and there is no stagnation.
The particles of solute retain its geometric shape.
For a non- dispersed powder with spherical particles a bit mathematical derivation leads
to the kinetics equation.
W01/3 – W 1/3 = KHCt
Where, W0 = Initial weight of the particles.
W = weight of the particles at t
KHC = Hixon – Crowell release rate constant.
T = Time
A plot of W01/3 – W 1/3 vs. time gives a straight line with a negative slope since
W increases with time.
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27. Hixon-crowel equation
0
1
2
3
0 50 100
tim e(in m in)
w01/3-w1/3
W01/3-
W1/3
APPLICATION
When this model is used, it is assumed that the release rate is limited by the drug particles
dissolution rate and not by the diffusion that might occur through the polymeric matrix.
This model has been used to describe the release characterize profile keeping in mind the
diminishing surface of the drug for values for a particles during the dissolution
Hixson – Crowell Model Kinetics Cont…
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28. Higuichi Model Kinetics
For coated or matrix type dosage form, the dissolution medium enters the dosage
form in order for the drug to be released and diffused into the bulk solution.
In such conditions, often the dissolution follows the equation proposed by
Higuichi
Q = [ DE (2A – Ecs) Cs/t]0.5
Or, Q = KHG t 0.5
Where, Q = Amount of drug released per unit area of the dosage form.
D = diffusion Coefficient of the drug.
E = porosity of the matrix
T = Tortuousity of the matrix
Cs = Saturation solubility of the drug in the surrounding liquid.
K HG = Higuichi Release Rate Constant.
Fitness of the data into various kinetics modes were assessed by determining the
correlation coefficient, the constants, for respective models were also calculated
from slope.
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29. Higuchi-equation
0
50
100
0 5 10
sqrt
%cdr
%cdr
APPLICATION
Higuchi describes drug release as a diffusion process based in the Fick’s law, square
root time dependant. This relation can be used to describe the drug dissolution
from several types of modified release pharmaceutical dosage forms, as in the case
of some transdermal and matrix tablets with water a soluble drugs
Higuichi Model Kinetics Cont….
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30. Koseymer-peppes model
The model explain that
Mt/Minf = ktn
Where Mt/Minf is a fraction of drug released at any time t;K is the release rate constant
incorporating the structural and geometric characteristics ; n is the diffusional exponent,
indicative of the release mechanism. (The value of n for a is <0.45 for Fickian release,
>0.45 and <0.89 for non-Fickian release, 0.89 for case II release, and >0.89 for super II
release) The values of K, n, and r (correlation co efficient), as obtained from the
dissolution data
KOSEMEYER-PEPPS
-1.5
-1
-0.5
0
0 2 4
LOG(TIME)
LOGMt/Minf
Series1
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31. Comparison of Dissolution Data
Dissimilarity Factor (f1) :
It was calculated in the comparison with reference or innovator product to
know the dissimilarity.
The dissimilarity factor (f1) should be always less than 10 (f1<10)
Rt - Tt
f1= ---------------× 100
Rt
Where
Rt = mean % dissolution of reference listed drug
Tt = mean % dissolution of our formulated product
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32. Similarity Factor (f2) :
The similarity factor (f2) was defined as the ‘logarithmic reciprocal
square root transformation of one plus the mean squared difference in
percent dissolved between the test and the reference products’. This
was calculated to compare the test with reference release profiles.
The similarity factor (f2) should be always greater than 50 (f2>50).
The method is more adequate to compare dissolution profiles when
more than three or four dissolution time points are available and can
only be applied if average difference between Rt and Tt is less than 100.
If this difference is higher than 100, normalization of data is required.
1
f2= 50 × log10 × ------------------------------- × 100
1+ 1/n × (Rt – Tt) 2
Where n= no. of sampling point
a
ALKEM
R & D
Comparison of Dissolution Data