This document discusses pharmaceutical suspensions. It defines suspensions as dispersions of solid drug particles in a liquid vehicle. Suspensions are classified based on particle size as molecular dispersions (<1nm), colloidal dispersions (1nm-0.5um) or coarse dispersions (>0.5um). Most pharmaceutical suspensions are coarse dispersions. The document outlines factors to consider in suspension formulation including particle wetting and size, sedimentation rate, electrokinetic properties, and methods of controlling flocculation. Structured vehicles and controlled flocculation are described as methods for producing stable suspensions. Key qualities of ideal suspensions are also provided such as resistance to settling and caking.
Suspension, interfacial properties of suspended particles, settling in suspensions, formulation of flocculated and deflocculated suspensions. Emulsions and theories of emulsification, microemulsion and multiple emulsions; Stability of emulsions, preservation of emulsions, rheological properties of emulsions.
The document discusses four methods of dispersion for preparing colloids: 1) Mechanical dispersion uses grinding to break large particles into smaller colloidal particles, 2) Electrical dispersion applies an electric arc to vaporize and disperse metal particles, 3) Peptization dispersion converts a precipitate into a colloidal sol using an electrolyte, and 4) Homogenization emulsifies substances like milk or cream to form a stable colloid.
This document discusses factors that affect the flow properties of powders. It describes three common tests to evaluate powder flowability: Carr's compressibility index, Hausner ratio, and angle of repose. Carr's index and Hausner ratio indicate flow based on tapped density measurements. Angle of repose measures the slope of a powder pile. The document also outlines factors like particle size, shape, surface forces, and additives that influence flow and methods to improve powder flow properties.
1. The document discusses different types of deformation that solids undergo when external forces are applied, including elastic deformation, plastic deformation, and breaking.
2. Elastic deformation is reversible and follows Hooke's Law, relating stress to strain linearly. Plastic deformation is irreversible and leads to a permanent change in shape.
3. The document also defines moduli that quantify a material's resistance to different types of deformation, including Young's modulus, shear modulus, and bulk modulus. These properties depend on the material and can be used to characterize its stiffness.
pellets can be defined as multi particulate system or multiunit system
They are spherical particulates manufactured by agglomeration of the powder granules containing drug substance and excipients.
Pellets can be prepared by a special technique called Pelletization.
This technique is referred to an agglomeration process that convert fine powder or granules of bulk drug or excipient in to small , free flowing , spherical or semi spherical pellets .
Multi particular drug delivery system especially suitable for achieving controlled delay released oral formulation with low risk of dose dumping, flexibility of blending to attain different release patterns as well as reproducible and short gastric residence time.
Multi particulate drug delivery system are mainly oral dosage form consisting of a multiplicity of small discrete units each exhibiting some desire characteristics.
Rotational Viscometers,
The viscometers that used to measure the viscosity using retarding force due to the viscous drag.
typers and sub-types, advantages,disadvantages,working of different rotational viscometers.
1.cup and bob viscometer,
2.cone and plate viscometer,
plug flow development, etc.
Chapter: Rheology
4th semester B.Pharm.
Physical Pharmacuetics,
B.pharm, As per the PCI semester syllabus,
!THIS SLIDE IS SIMPLIFIED BULLETINS, USE THIS SLIDE AND REFER MORE RESPECTIVE TEXTBOOKS!.
THANK YOU:
This document discusses different methods for purifying colloidal dispersions, including dialysis, electrodialysis, and ultrafiltration. Dialysis involves diffusing low molecular weight impurities out of a colloidal solution through a semi-permeable membrane. Electrodialysis enhances this diffusion process by applying an electric potential. Ultrafiltration uses an ultrafilter membrane with small pores to retain colloidal particles while filtering out smaller solutes under pressure.
Coarse dispersions are heterogeneous systems where the dispersed particles are larger than 1000 nm. They are characterized by relatively fast sedimentation. The dispersed phase may be easily separated from the continuous phase by filtration. A pharmaceutical suspension is a coarse dispersion where the internal phase is uniformly dispersed throughout the external phase. The internal phase typically has particle sizes between 0.5-5 microns. Suspensions demonstrate properties like pseudoplasticity and thixotropy which influence stability during manufacture and storage.
Suspension, interfacial properties of suspended particles, settling in suspensions, formulation of flocculated and deflocculated suspensions. Emulsions and theories of emulsification, microemulsion and multiple emulsions; Stability of emulsions, preservation of emulsions, rheological properties of emulsions.
The document discusses four methods of dispersion for preparing colloids: 1) Mechanical dispersion uses grinding to break large particles into smaller colloidal particles, 2) Electrical dispersion applies an electric arc to vaporize and disperse metal particles, 3) Peptization dispersion converts a precipitate into a colloidal sol using an electrolyte, and 4) Homogenization emulsifies substances like milk or cream to form a stable colloid.
This document discusses factors that affect the flow properties of powders. It describes three common tests to evaluate powder flowability: Carr's compressibility index, Hausner ratio, and angle of repose. Carr's index and Hausner ratio indicate flow based on tapped density measurements. Angle of repose measures the slope of a powder pile. The document also outlines factors like particle size, shape, surface forces, and additives that influence flow and methods to improve powder flow properties.
1. The document discusses different types of deformation that solids undergo when external forces are applied, including elastic deformation, plastic deformation, and breaking.
2. Elastic deformation is reversible and follows Hooke's Law, relating stress to strain linearly. Plastic deformation is irreversible and leads to a permanent change in shape.
3. The document also defines moduli that quantify a material's resistance to different types of deformation, including Young's modulus, shear modulus, and bulk modulus. These properties depend on the material and can be used to characterize its stiffness.
pellets can be defined as multi particulate system or multiunit system
They are spherical particulates manufactured by agglomeration of the powder granules containing drug substance and excipients.
Pellets can be prepared by a special technique called Pelletization.
This technique is referred to an agglomeration process that convert fine powder or granules of bulk drug or excipient in to small , free flowing , spherical or semi spherical pellets .
Multi particular drug delivery system especially suitable for achieving controlled delay released oral formulation with low risk of dose dumping, flexibility of blending to attain different release patterns as well as reproducible and short gastric residence time.
Multi particulate drug delivery system are mainly oral dosage form consisting of a multiplicity of small discrete units each exhibiting some desire characteristics.
Rotational Viscometers,
The viscometers that used to measure the viscosity using retarding force due to the viscous drag.
typers and sub-types, advantages,disadvantages,working of different rotational viscometers.
1.cup and bob viscometer,
2.cone and plate viscometer,
plug flow development, etc.
Chapter: Rheology
4th semester B.Pharm.
Physical Pharmacuetics,
B.pharm, As per the PCI semester syllabus,
!THIS SLIDE IS SIMPLIFIED BULLETINS, USE THIS SLIDE AND REFER MORE RESPECTIVE TEXTBOOKS!.
THANK YOU:
This document discusses different methods for purifying colloidal dispersions, including dialysis, electrodialysis, and ultrafiltration. Dialysis involves diffusing low molecular weight impurities out of a colloidal solution through a semi-permeable membrane. Electrodialysis enhances this diffusion process by applying an electric potential. Ultrafiltration uses an ultrafilter membrane with small pores to retain colloidal particles while filtering out smaller solutes under pressure.
Coarse dispersions are heterogeneous systems where the dispersed particles are larger than 1000 nm. They are characterized by relatively fast sedimentation. The dispersed phase may be easily separated from the continuous phase by filtration. A pharmaceutical suspension is a coarse dispersion where the internal phase is uniformly dispersed throughout the external phase. The internal phase typically has particle sizes between 0.5-5 microns. Suspensions demonstrate properties like pseudoplasticity and thixotropy which influence stability during manufacture and storage.
Liquid oral topic in Industrial Pharmacy contains many topics like solution, elixirs, syrups, emulsion, and suspension. This topic includes general introduction, types, formulation, components, uses, and Quality control tests. These are also beneficial in other subjects like Pharmaceutics.
An emulsion is a dispersion of one liquid into another immiscible liquid. The key types are oil-in-water (O/W) and water-in-oil (W/O) emulsions. Emulsions have various pharmaceutical applications like masking unpleasant tastes and enhancing drug absorption. Emulsion stability and type depend on factors like the emulsifying agent used, its HLB value, and emulsion preparation method. Common tests are used to identify the emulsion type and stability must be ensured through proper preservation, packaging, and storage.
The document discusses accelerated stability testing which uses exaggerated storage conditions to rapidly assess a drug product's stability over time. It describes the Arrhenius equation which relates reaction rate to temperature and activation energy. Common accelerated tests involve storing samples at elevated temperatures, humidity, oxygen, or light levels. While useful, accelerated testing has limitations when degradation depends on other factors like microbes or diffusion. ICH guidelines provide standard methods for stability testing and data analysis.
This document summarizes several theories of emulsions:
- The monomolecular adsorption theory explains how emulsifying agents reduce interfacial tension by adsorbing at the oil-water interface to form monolayer films. Combinations of hydrophilic and hydrophobic emulsifiers are often used to form complex films.
- The oriented-wedge theory describes how emulsifying agents curve around emulsion droplets, with their structure "fitting" the curvature.
- The plastic or interfacial film theory views emulsifying agents forming a thin layer surrounding droplets, with water-soluble agents favoring oil-in-water emulsions and vice versa.
- Other theories addressed include the surface tension theory, inter
This document provides information about pharmaceutical suspensions. It begins by defining a suspension as a disperse system where an insoluble solid internal phase is uniformly dispersed throughout an external liquid phase. Particle size is important for suspensions to be classified as coarse or colloidal. Suspensions differ from solutions in that particles remain dispersed rather than dissolving. Sedimentation occurs over time due to particle size and density. Suspending agents are added to prevent sedimentation by increasing viscosity. The document discusses formulation, applications, advantages, and disadvantages of suspensions.
This theory is explain by Derjaguin , Landau , Verway , Overbeek So it is known as DLVO Theory.
According to this theory , The forces on colloidal particles in a dispersion medium are due to –
1. Electrostatic Repulsion
2. London type Vander Waals Attraction
Micromeritics, the science of small particles, is important for drug formulation and delivery. Particle size influences properties like surface area, dissolution rate, absorption and drug action. It also impacts physical stability of suspensions and emulsions. Various methods can determine particle size, including microscopy, sieving, and sedimentation. Derived powder properties like porosity, density, bulkiness, and flowability depend on particle size, shape, and surface properties. Tests like Carr's index and angle of repose evaluate powder flowability. Altering particle features and adding glidants can improve powder flow in formulations.
A comprehensive interpretation of pellets based on their definitions, advantages, disadvantages, mechanism of pellet formation and growth, pelletization techniques, formulation requirements, and the equipment system for manufacture of pellets.
This document discusses the solubility of drugs and defines key terms like solute, solvent, and solution. It explains that solubility is the concentration of a substance that dissolves in a solvent to form a homogeneous mixture. The mechanism of solute-solvent interactions is discussed, noting that "like dissolves like" and factors like temperature, pressure, and pH influence solubility. Solubility expressions are provided to classify solubility from very soluble to practically insoluble. The document also discusses solubility of gases, liquids, ideal and non-ideal solutions, azeotropes, and Nerst's distribution law.
Pharmaceutical Emulsions are thermodynamically unstable mixtures of two immiscible liquids stabilized by an emulsifying agent. They can be oil-in-water (O/W) or water-in-oil (W/O) emulsions depending on the dispersed and continuous phases. Emulsifying agents like surfactants, hydrocolloids, and solid particles form protective films around droplets and increase viscosity to prevent coalescence. Stability issues include creaming, cracking, and phase inversion. Methods to enhance stability are reducing droplet size, increasing viscosity, using emulsifying agents, and controlling storage temperature.
Accelerated stability studies, Arrhenius equation, steps involved in prediction of shelf life, climatic zones as per the ICH guidelines, limitations of Accelerated stability study
This document discusses colloidal dispersions and their characteristics. It begins by defining colloidal dispersions as polyphasic systems where at least one dimension of the dispersed phase measures between 1 nm and 1 micrometer. It then discusses various types of colloidal dispersions including lyophilic, lyophobic, and association colloids. The document also covers characteristics of the dispersed phase such as particle size, shape, surface area, and surface charge. It discusses techniques for studying colloidal dispersions such as optical properties, kinetic properties, electrical properties, and more. In summary, the document provides an overview of colloidal dispersion systems and methods used to analyze their properties.
This document discusses rheology, which is the branch of physics dealing with the deformation and flow of liquids. It provides definitions and examples of different types of fluid flow, including Newtonian, plastic, pseudoplastic, and dilatant flow. Key aspects covered include viscosity, shear stress, yield value, and the effects of temperature, particle concentration, and other factors on rheological properties. Common instruments used to measure viscosity, such as capillary, falling sphere, cup and bob, and cone and plate viscometers are also described.
This document discusses surface and interfacial phenomena. It defines interfaces and divides them into solid and liquid interfaces. Liquid interfaces deal with liquid-gas or liquid-liquid phases and have applications in infiltration, biopharmaceuticals, and suspensions/emulsions. Surface tension exists between solid-gas and liquid-gas phases, while interfacial tension exists between immiscible liquids. Various methods are described to measure surface tension, interfacial tension, and surface free energy. Surfactants are also discussed, including how they lower tensions and are used in products. Adsorption at interfaces and isotherms are briefly covered.
Pharmaceutical aerosols are therapeutic active ingredients packaged in a pressurized system. They have advantages like direct delivery to affected areas without contamination. Aerosols consist of a propellant, container, valve, and product concentrate. Common propellants include hydrocarbons and gases. Containers must withstand high pressure and are often metal or glass. Valves meter doses and come in types like spray or foam. Formulations contain an active ingredient and propellant to achieve desired properties. Quality is ensured through testing of components, dosage, leakage and other parameters.
This document discusses rheological properties of emulsions. It explains that emulsions often exhibit non-Newtonian flow, making their rheological properties complex. The factors that influence emulsion rheology include properties of the dispersed phase like volume fraction, particle size, and viscosity, properties of the continuous phase like viscosity, and the type and concentration of emulsifying agent used. Understanding how formulation impacts rheology allows pharmacists to develop emulsions with appropriate flow properties for their intended uses and manufacturing processes.
R. VIJAYAKUMAR., M Pharm,
Research Scholar
department of Pharmaceutical Technology.
Anna university- BIT
Tiruchirappalli
III Semester.
UNIT-IV / Micromeritics
The document discusses various properties of powders including porosity, density, bulkiness, and flow properties. It defines porosity as the ratio of void volume to bulk volume. There are three types of densities: true density, bulk density, and granule density. Bulkiness is defined as the reciprocal of bulk density. Flow properties are important for pharmaceutical dosage forms and can be evaluated using tests like Carr's compressibility index and Hausner ratio. Factors like particle size, shape, surface forces, addition of fines, and flow activators affect powder flowability.
The document discusses thixotropy, which is defined as the reversible transformation of a semi-solid material from a solid state to a liquid state and back again due to applied stress over time. Examples of thixotropic materials include ketchup, paints, and yogurt. A key characteristic of thixotropic materials is their hysteresis loop, which is formed on a rheogram by the upcurve and downcurve of viscosity with increasing and decreasing shear rates. The area of the hysteresis loop can be used to measure the degree of thixotropic breakdown. Thixotropy is a desirable property for liquid pharmaceuticals as it allows the material to have a high consistency at rest but flow easily upon shaking before reg
This document provides an overview of pharmaceutical emulsions. It defines emulsions as dispersions of one liquid in another immiscible liquid, stabilized by an emulsifying agent. The key topics covered include the classification of emulsions as oil-in-water or water-in-oil, theories of emulsification, common emulsifying agents like surfactants and hydrocolloids, and factors affecting the stability of emulsions such as flocculation and creaming. Pharmaceutical applications of emulsions include lotions, creams, and ointments.
This document provides information about pharmaceutical suspensions. It defines a suspension as a coarse dispersion where an insoluble solid active ingredient is uniformly dispersed throughout an external aqueous or non-aqueous liquid phase. Suspensions are formulated when drugs are insoluble, to mask bitter tastes, increase stability, or achieve sustained release. Key factors in formulating stable suspensions include particle size, shape, wettability, and use of suspending agents to decrease interparticle attraction and impart viscosity. Proper manufacturing controls suspension quality.
Liquid oral topic in Industrial Pharmacy contains many topics like solution, elixirs, syrups, emulsion, and suspension. This topic includes general introduction, types, formulation, components, uses, and Quality control tests. These are also beneficial in other subjects like Pharmaceutics.
An emulsion is a dispersion of one liquid into another immiscible liquid. The key types are oil-in-water (O/W) and water-in-oil (W/O) emulsions. Emulsions have various pharmaceutical applications like masking unpleasant tastes and enhancing drug absorption. Emulsion stability and type depend on factors like the emulsifying agent used, its HLB value, and emulsion preparation method. Common tests are used to identify the emulsion type and stability must be ensured through proper preservation, packaging, and storage.
The document discusses accelerated stability testing which uses exaggerated storage conditions to rapidly assess a drug product's stability over time. It describes the Arrhenius equation which relates reaction rate to temperature and activation energy. Common accelerated tests involve storing samples at elevated temperatures, humidity, oxygen, or light levels. While useful, accelerated testing has limitations when degradation depends on other factors like microbes or diffusion. ICH guidelines provide standard methods for stability testing and data analysis.
This document summarizes several theories of emulsions:
- The monomolecular adsorption theory explains how emulsifying agents reduce interfacial tension by adsorbing at the oil-water interface to form monolayer films. Combinations of hydrophilic and hydrophobic emulsifiers are often used to form complex films.
- The oriented-wedge theory describes how emulsifying agents curve around emulsion droplets, with their structure "fitting" the curvature.
- The plastic or interfacial film theory views emulsifying agents forming a thin layer surrounding droplets, with water-soluble agents favoring oil-in-water emulsions and vice versa.
- Other theories addressed include the surface tension theory, inter
This document provides information about pharmaceutical suspensions. It begins by defining a suspension as a disperse system where an insoluble solid internal phase is uniformly dispersed throughout an external liquid phase. Particle size is important for suspensions to be classified as coarse or colloidal. Suspensions differ from solutions in that particles remain dispersed rather than dissolving. Sedimentation occurs over time due to particle size and density. Suspending agents are added to prevent sedimentation by increasing viscosity. The document discusses formulation, applications, advantages, and disadvantages of suspensions.
This theory is explain by Derjaguin , Landau , Verway , Overbeek So it is known as DLVO Theory.
According to this theory , The forces on colloidal particles in a dispersion medium are due to –
1. Electrostatic Repulsion
2. London type Vander Waals Attraction
Micromeritics, the science of small particles, is important for drug formulation and delivery. Particle size influences properties like surface area, dissolution rate, absorption and drug action. It also impacts physical stability of suspensions and emulsions. Various methods can determine particle size, including microscopy, sieving, and sedimentation. Derived powder properties like porosity, density, bulkiness, and flowability depend on particle size, shape, and surface properties. Tests like Carr's index and angle of repose evaluate powder flowability. Altering particle features and adding glidants can improve powder flow in formulations.
A comprehensive interpretation of pellets based on their definitions, advantages, disadvantages, mechanism of pellet formation and growth, pelletization techniques, formulation requirements, and the equipment system for manufacture of pellets.
This document discusses the solubility of drugs and defines key terms like solute, solvent, and solution. It explains that solubility is the concentration of a substance that dissolves in a solvent to form a homogeneous mixture. The mechanism of solute-solvent interactions is discussed, noting that "like dissolves like" and factors like temperature, pressure, and pH influence solubility. Solubility expressions are provided to classify solubility from very soluble to practically insoluble. The document also discusses solubility of gases, liquids, ideal and non-ideal solutions, azeotropes, and Nerst's distribution law.
Pharmaceutical Emulsions are thermodynamically unstable mixtures of two immiscible liquids stabilized by an emulsifying agent. They can be oil-in-water (O/W) or water-in-oil (W/O) emulsions depending on the dispersed and continuous phases. Emulsifying agents like surfactants, hydrocolloids, and solid particles form protective films around droplets and increase viscosity to prevent coalescence. Stability issues include creaming, cracking, and phase inversion. Methods to enhance stability are reducing droplet size, increasing viscosity, using emulsifying agents, and controlling storage temperature.
Accelerated stability studies, Arrhenius equation, steps involved in prediction of shelf life, climatic zones as per the ICH guidelines, limitations of Accelerated stability study
This document discusses colloidal dispersions and their characteristics. It begins by defining colloidal dispersions as polyphasic systems where at least one dimension of the dispersed phase measures between 1 nm and 1 micrometer. It then discusses various types of colloidal dispersions including lyophilic, lyophobic, and association colloids. The document also covers characteristics of the dispersed phase such as particle size, shape, surface area, and surface charge. It discusses techniques for studying colloidal dispersions such as optical properties, kinetic properties, electrical properties, and more. In summary, the document provides an overview of colloidal dispersion systems and methods used to analyze their properties.
This document discusses rheology, which is the branch of physics dealing with the deformation and flow of liquids. It provides definitions and examples of different types of fluid flow, including Newtonian, plastic, pseudoplastic, and dilatant flow. Key aspects covered include viscosity, shear stress, yield value, and the effects of temperature, particle concentration, and other factors on rheological properties. Common instruments used to measure viscosity, such as capillary, falling sphere, cup and bob, and cone and plate viscometers are also described.
This document discusses surface and interfacial phenomena. It defines interfaces and divides them into solid and liquid interfaces. Liquid interfaces deal with liquid-gas or liquid-liquid phases and have applications in infiltration, biopharmaceuticals, and suspensions/emulsions. Surface tension exists between solid-gas and liquid-gas phases, while interfacial tension exists between immiscible liquids. Various methods are described to measure surface tension, interfacial tension, and surface free energy. Surfactants are also discussed, including how they lower tensions and are used in products. Adsorption at interfaces and isotherms are briefly covered.
Pharmaceutical aerosols are therapeutic active ingredients packaged in a pressurized system. They have advantages like direct delivery to affected areas without contamination. Aerosols consist of a propellant, container, valve, and product concentrate. Common propellants include hydrocarbons and gases. Containers must withstand high pressure and are often metal or glass. Valves meter doses and come in types like spray or foam. Formulations contain an active ingredient and propellant to achieve desired properties. Quality is ensured through testing of components, dosage, leakage and other parameters.
This document discusses rheological properties of emulsions. It explains that emulsions often exhibit non-Newtonian flow, making their rheological properties complex. The factors that influence emulsion rheology include properties of the dispersed phase like volume fraction, particle size, and viscosity, properties of the continuous phase like viscosity, and the type and concentration of emulsifying agent used. Understanding how formulation impacts rheology allows pharmacists to develop emulsions with appropriate flow properties for their intended uses and manufacturing processes.
R. VIJAYAKUMAR., M Pharm,
Research Scholar
department of Pharmaceutical Technology.
Anna university- BIT
Tiruchirappalli
III Semester.
UNIT-IV / Micromeritics
The document discusses various properties of powders including porosity, density, bulkiness, and flow properties. It defines porosity as the ratio of void volume to bulk volume. There are three types of densities: true density, bulk density, and granule density. Bulkiness is defined as the reciprocal of bulk density. Flow properties are important for pharmaceutical dosage forms and can be evaluated using tests like Carr's compressibility index and Hausner ratio. Factors like particle size, shape, surface forces, addition of fines, and flow activators affect powder flowability.
The document discusses thixotropy, which is defined as the reversible transformation of a semi-solid material from a solid state to a liquid state and back again due to applied stress over time. Examples of thixotropic materials include ketchup, paints, and yogurt. A key characteristic of thixotropic materials is their hysteresis loop, which is formed on a rheogram by the upcurve and downcurve of viscosity with increasing and decreasing shear rates. The area of the hysteresis loop can be used to measure the degree of thixotropic breakdown. Thixotropy is a desirable property for liquid pharmaceuticals as it allows the material to have a high consistency at rest but flow easily upon shaking before reg
This document provides an overview of pharmaceutical emulsions. It defines emulsions as dispersions of one liquid in another immiscible liquid, stabilized by an emulsifying agent. The key topics covered include the classification of emulsions as oil-in-water or water-in-oil, theories of emulsification, common emulsifying agents like surfactants and hydrocolloids, and factors affecting the stability of emulsions such as flocculation and creaming. Pharmaceutical applications of emulsions include lotions, creams, and ointments.
This document provides information about pharmaceutical suspensions. It defines a suspension as a coarse dispersion where an insoluble solid active ingredient is uniformly dispersed throughout an external aqueous or non-aqueous liquid phase. Suspensions are formulated when drugs are insoluble, to mask bitter tastes, increase stability, or achieve sustained release. Key factors in formulating stable suspensions include particle size, shape, wettability, and use of suspending agents to decrease interparticle attraction and impart viscosity. Proper manufacturing controls suspension quality.
This document discusses pharmaceutical suspensions. It begins by defining suspensions as heterogeneous systems with one substance dispersed in small units throughout another substance. Suspensions are classified based on route of administration and electrokinetic nature. Benefits include masking unpleasant tastes and controlling drug release. Challenges include physical instability and accurate dosing. Key factors in developing suspensions are preventing sedimentation, achieving uniformity, and pleasing attributes. Formulation considers vehicle structure, controlled flocculation, suspending agents, viscosity, surface tension, wetting agents, and solvents.
If iced tea mix is stirred into water, it would form a homogeneous solution. The tea mix particles would be too small to separate out or filter from the water. Over several days, the drink would not separate into distinct layers. Solutions like this form a single phase because the solute particles are small enough to dissolve uniformly throughout the solvent.
Pharmaceutical suspensions... a brief reviewbk fatima
This document provides information on suspensions, including:
- Definitions of suspensions and their advantages over other dosage forms.
- Classification of suspensions based on factors like concentration, particle size, and sedimentation.
- Guidelines for formulating stable suspensions, such as using suspending agents and controlling flocculation.
- Methods for evaluating properties of suspensions like sedimentation, viscosity, and particle size over time to assess stability.
- Common suspending agents used to increase viscosity and prevent caking or sedimentation.
This document discusses suspensions, which are two-phase systems consisting of finely divided solid particles dispersed in a liquid vehicle. Suspensions can be classified based on administration route or particle size. They are useful for drugs with low solubility and can improve stability, release properties, and bioavailability compared to other dosage forms. However, suspensions are also prone to physical instability issues like sedimentation. The document outlines factors that affect sedimentation and strategies to improve suspension stability such as controlling particle size, viscosity, surface charge, and use of surfactants or flocculating agents. Wetting agents are also discussed which help disperse solid particles in the liquid vehicle by reducing surface tension.
The suspension system connects a vehicle to its wheels and serves two main purposes. It contributes to the vehicle's handling and braking while also protecting the vehicle and passengers from damage caused by bumps and vibrations in the road. The basic components of a suspension system include control arms, ball joints, springs, shock absorbers, and other linkages which work together to support the vehicle's weight and allow for steering and a smooth ride. Modern systems often use coil springs and shock absorbers in independent designs for each wheel.
This document discusses the classification of mixtures as solutions, suspensions, or colloids based on particle size. Solutions are homogeneous mixtures where particles are too small to scatter light or be filtered out. Suspensions are heterogeneous mixtures where particles are large enough to separate over time by settling or being filtered. Colloids have intermediate particle sizes that do not separate but can scatter light.
Pharmaceutical suspensions are heterogeneous mixtures containing solid particles dispersed in a liquid medium. They allow insoluble drugs to be formulated into liquid dosage forms. Suspensions are administered via several routes including orally, ocularly, parenterally, and topically. Qualities of a good suspension include maintaining homogeneity during use and easy re-suspension of sediment. Suspensions have advantages over other dosage forms like permitting formulation of poorly soluble drugs and prolonging drug action.
This document discusses different types of suspensions including flocculated and structured vehicle suspensions. It defines key terms like electrostatic repulsive force, steric repulsive force, and van der Waals forces that influence particle interactions. Methods for controlling these interparticle forces through formulation are presented for flocculating particles and producing shear thinning structured vehicles. Examples of adjusting surface charge and adding polymers or clays are given. Properties of flocculated and structured vehicle suspensions are compared.
Suspension is made of two phase system, consisting of a finely divided solid particles (Dispersed phase) distributed in a particular manner throughout another medium (Continuous phase).
The document discusses spring rates, motion ratios, roll stiffness, and anti-roll bars. It provides equations to calculate spring rates for coil springs and torsion bars based on material properties and geometry. Motion ratio is defined as the displacement ratio between the spring and wheel center, and affects wheel rate. Roll stiffness is determined from individual wheel rates and track width. Asymmetric spring rates and locations are also addressed. Anti-roll bars contribute additional roll stiffness that depends on bar properties and motion ratio.
In process quality control of suspensions and emulsionsceutics1315
This document discusses in-process quality control of suspensions and emulsions. It defines in-process quality control as controlling manufacturing procedures from raw materials to final product packaging. Key tests for suspensions include appearance, particle size, zeta potential, viscosity, sedimentation rate and redispersibility. Maintaining proper pH, drug content uniformity and monitoring manufacturing areas are also important. Tests for emulsions include appearance, droplet size, viscosity, creaming index and phase separation. Proper documentation of quality control procedures and parameters is necessary to ensure batch uniformity and quality.
Matter is everything that takes up space and has mass. There are two categories of matter: pure substances and mixtures. Pure substances have uniform composition while mixtures have varying compositions. Elements are pure substances made of only one type of atom, while compounds are made of two or more elements chemically bonded together. Mixtures can be either homogeneous, meaning the parts are evenly distributed and not visible to the eye, or heterogeneous, meaning the parts are unevenly distributed and visible. Physical properties can be used to identify, select, and separate materials. Common physical separation methods include filtration and distillation.
The document discusses emulsions, which are mixtures of two or more liquids that do not normally mix. It defines the key types of emulsions as oil-in-water (O/W), water-in-oil (W/O), and multiple emulsions. It also explains the differences between O/W and W/O emulsions and describes detection tests that can identify the emulsion type. Finally, it provides examples of common emulsifying agents like lecithin, soap, and gum and discusses their properties and uses in emulsions.
The suspension system connects a vehicle to its wheels using springs, shock absorbers, and linkages. It serves two main purposes - contributing to handling and braking, and protecting the vehicle and passengers from road shocks. Common suspension types include independent front suspensions like MacPherson struts and solid rear axles with leaf springs. Proper suspension provides cushioning, stability, and ride comfort while preventing excess body movement.
This document discusses rheology, which is the science of flow and deformation of materials. It defines rheology and explains its importance in pharmaceutical applications. It describes different types of flows including Newtonian, plastic, pseudoplastic and dilatant flows. It also discusses thixotropic behavior, instrumentation used to study rheology including viscometers, and applications of rheology in areas like creams, lotions and suspensions.
An emulsion is an unstable mixture of two immiscible liquids stabilized by an emulsifying agent. Emulsions have various pharmaceutical applications including oral and topical drug delivery. The type of emulsion (e.g. oil-in-water, water-in-oil) depends on the relative solubility of the emulsifying agent. Emulsions can be prepared using different methods such as the dry gum, wet gum, or bottle methods. Drugs can be incorporated into emulsions during or after emulsion formation.
The document discusses various types of automobile suspension systems. It describes independent suspension systems that allow each wheel to move independently and non-independent systems where the wheels are attached to a solid axle. Common types of independent suspension include MacPherson strut suspension, wishbone suspension, and solid rear axle suspension. The document also covers suspension components like springs, shock absorbers, control arms, and sway bars. It provides advantages and disadvantages of different suspension types.
This document discusses pharmaceutical suspensions, including their definition, classification, formulation, preparation, advantages, and disadvantages. A suspension is a biphasic system with solid particles dispersed uniformly throughout a liquid medium. Key points covered include the use of wetting agents, suspending agents, thickeners, buffers, coloring agents, and preservatives in formulation. Methods for preparation involve reducing particle size and using processes like precipitation, dispersion, and controlled flocculation to obtain a uniformly suspended product.
The document discusses suspensions, including definitions, classifications, properties, advantages, disadvantages, formulation methods, components, and general formulation procedures. Some key points:
- A suspension is a heterogeneous system with insoluble particles dispersed uniformly throughout a liquid medium. Suspending agents help maintain uniform dispersion.
- Suspensions can be classified based on physical state, proportion of solids, behavior of dispersed phase, particle size, and general type (oral, topical, parenteral).
- Important properties include easy redispersion, no sediment compaction, optimal viscosity, and stability.
- Common formulation methods are precipitation, dispersion, controlled flocculation, and use of structured vehicles. Key components are suspending
The document discusses suspensions, including definitions, classifications, properties, advantages, disadvantages, formulation methods, components, and equipment used. A suspension is a heterogeneous system with small insoluble particles dispersed uniformly throughout a liquid medium. Suspensions can be classified based on physical state, proportion of solids, particle behavior, size, and application (oral, topical, parenteral). Key aspects in formulation include reducing particle size, selecting suspending agents, wetting agents, and structured vehicles. Common equipment used are mortar and pestle, mechanical stirrers, colloid mills, homogenizers, and ultrasonic devices.
This document provides information about a pharmaceutical suspension submitted by Rahul Raj, a B-Pharmacy student with roll number 045. It begins with an introduction that defines suspensions and classifies them based on physical state, proportion of solid particles, behavior of dispersed phase, size of dispersed particles, and general use. The document then discusses properties of well-formulated suspensions, advantages and disadvantages of suspensions, and various methods for formulating suspensions including precipitation, dispersion, controlled flocculation, and use of structured vehicles. It provides a general procedure for suspension formulation and includes flow charts. Finally, it details common formulation components such as suspending agents, wetting agents, surfactants, hydrophilic colloids, solvents
Suspension is a two-phase system with a solid dispersed in a liquid. Suspensions offer advantages like masking unpleasant tastes, providing prolonged drug release, and increased bioavailability. Factors like particle size, viscosity, and density difference between solid and liquid affect sedimentation rate per Stokes' law. Formulating stable suspensions requires choosing vehicles that maintain particles in deflocculated state or produce redispersible floccules. Wetting powder particles thoroughly before adding to the vehicle aids in proper dispersion.
This document discusses suspensions, including their definition as a disperse system with one substance distributed in particulate form throughout another. Suspensions are divided into coarse suspensions with particles over 1 μm and colloidal suspensions with particles under 1 μm. Suspensions can be used orally when patients have difficulty swallowing solids or to provide faster dissolution than solids. Proper formulation requires controlling particle size, viscosity, wetting, sedimentation, flocculation, and stability. Common suspending agents include natural polysaccharides, semisynthetic polysaccharides, clays, and synthetic polymers.
This document provides information about pharmaceutical suspensions. It defines a suspension as a dispersed system where one substance is distributed in particulate form throughout another. Suspensions are formulated for reasons such as insolubility, taste-masking, or controlled drug release. Key aspects of formulating suspensions include controlling particle size, using thickening agents to increase viscosity, and adding surfactants to improve wetting. Common thickening agents discussed are natural polysaccharides like acacia, tragacanth, and sodium alginate as well as semi-synthetic agents like methylcellulose and sodium carboxymethylcellulose.
A dispersion is a system in which distributed particles of one material are dispersed in a continuous phase of another material. The two phases may be in the same or different states of matter.
Introduction
Definition
Features desired in pharmaceutical suspension
Advantage/Disadvantages of pharmaceutical suspension
Flocculated and deflocculated suspension
Interfacial properties of suspending particles
Settling in suspensions
Effect of Brownian movement,
Sedimentation of flocculated particles,
Sedimentation parameters
Formulation of suspensions
Wetting of Particles,
Controlled flocculation,
Flocculation in structured vehicle
Suspensions are liquid dosage forms containing finely dispersed solid particles. They are used for drugs that are insoluble, unstable, or need to be absorbed slowly. Suspensions can be administered orally, ocularly, otically, rectally, parenterally, or topically. Factors in formulation include the nature and size of particles, viscosity, and physical stability. Structured vehicles and controlled flocculation are used to prepare deflocculated and flocculated suspensions, respectively. Evaluation tests assess properties like sedimentation, redispersibility, and zeta potential. Packaging requires containers with headspace and instructions to shake before use.
This document discusses suspensions, including definitions, classifications, formulation, packing, evaluation, and storage. Suspensions are defined as preparations containing finely divided drug particles distributed uniformly throughout a vehicle. They are classified based on factors such as intended use (oral, external, parenteral), nature of solid particles (flocculated, deflocculated), and proportion of solid particles. Formulation involves selecting appropriate suspending agents, thickeners, and preservatives. Suspensions are packed in containers allowing for mixing and evaluated using sedimentation, rheological, and electrokinetic methods. Proper storage conditions help maintain stability.
Manufacturing Flow Chart And IPQC Test Of SUSPENSIONAditi Roy
This document discusses in-process quality control tests for pharmaceutical suspensions. Some key tests mentioned include visual inspection of appearance and purity, measuring properties like density, pH, clarity and sedimentation volume over time. Electrokinetic methods like zeta potential measurement and microscopic analysis of particle size distribution are also described. Content uniformity testing and ensuring redispersibility upon shaking are emphasized for control during production.
Pharmaceutical suspensions are coarse dispersions containing finely divided insoluble material suspended in a liquid medium. Suspensions are classified based on their solid content as either dilute (<10% w/v) or concentrated (>50% w/v). They can also be classified as either flocculated or deflocculated based on the behavior of the suspended particles. Flocculated suspensions have particles that form loose aggregates called floes, resulting in faster sedimentation, while deflocculated suspensions have particles that remain individually dispersed, resulting in slower sedimentation. The rate of sedimentation is influenced by factors like particle size, shape, density, and viscosity of the dispersion medium. Sedimentation and flocculation can be quantified
This document discusses pharmaceutical suspensions. It begins by defining a suspension as a coarse dispersion containing finely divided insoluble material suspended in a liquid medium. Suspensions are classified as either dilute or concentrated based on the proportion of solid, and as flocculated or deflocculated based on particle behavior. Flocculated suspensions have particles that form loose aggregates (flocs) while deflocculated suspensions have individually dispersed particles. The document outlines factors that influence particle settling such as size, shape, density, and viscosity. It provides quantitative expressions for sedimentation volume and degree of flocculation. Finally, it discusses formulation considerations for suspensions and methods for controlled flocculation using electrolytes or polymers.
Biphasic liquid dosage forms include emulsions and suspensions. Suspensions contain finely divided solid drug particles 0.5-3 microns in diameter dispersed throughout a liquid or semisolid vehicle. Ideal suspensions do not sediment or form cakes and are viscous enough to pour easily while being chemically stable. Suspensions offer benefits like ease of large dose formulation and administration to children/elderly but accuracy and absorption rate are disadvantages. Suspensions are classified by route of administration and properties of dispersed phase. Formulation involves consideration of the drug, wetting agents, suspending agents, vehicle, and preservative.
The document discusses suspensions, including their definition as a disperse system with one substance finely distributed in another, classifications based on particle size and use, properties of good suspensions, common issues like sedimentation and caking, and how to prevent them through factors like particle size, density difference, viscosity, and use of flocculating agents, suspending agents, and preservatives. Examples of pharmaceutical suspensions are provided for oral, topical, and parenteral uses.
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Suspensions
1. • Dispersion system consist of (1)- particulate matter (dispersed phase)
(2)- continuous medium (dispersion medium)
• Classification of dispersed systems (based on particle size)
1 Molecular
dispersion
< 1 nm Oxygen molecules,
glucose solution
2 Colloidal
dispersion
1nm- 0.5 mm Natural polymers
3
Coarse
dispersion
> 0.5 mm Suspension and
emulsion
• Definition of suspension: Pharmaceutical suspensions are uniform
dispersions of solid drug particles in a vehicle in which the drug has
minimum solubility. Particle size of the drugs may vary from one
formulation to the other depending on the physicochemical
characteristics of the drug and the rheological properties of the
formulation.
• A suspension containing particles between 1 nm to 0.5 µm in size is
called colloidal suspension. When the particle size is between 1 to
100 µm, the suspension is called coarse suspension. Most of the
pharmaceutical suspensions are coarse suspension.
• Majority of the marketed suspensions are available as dry powders
that must be reconstituted before administration but occasionally
1
2. some products in the market are ready-to-use. The first products are
not very stable once reconstituted; must be used within 7 to 10 days.
Examples of Pharmaceutical Suspensions:
A. Antacid oral suspensions Antibacterial oral suspension
B. Dry powders for oral suspension (antibiotic)
C. Analgesic oral suspension
D. Anthelmentic oral suspension
E. Anticonvulsant oral suspension
F. Antifungal oral suspension
Pharmaceutical applications of suspensions:
1) Insoluble drug or poorly soluble drugs which required to be given
orally in liquid dosage forms ( in case of children, elderly, and
patients have difficulty in swallowing solids dosage forms)
2) To over come the instability of certain drug in aqueous solution:
a. Insoluble derivative formulated as suspension
AN EXAMPLE IS OXYTETRACYCLINE HCL ⇒ CALCIUM SALT
(instable) (stable)
b. Reduce the contact time between solid drug particles and
dispersion media ⇒ increase the stability of drug like Ampicillin
by making it as reconstituted powder.
2
3. c. A drug that degraded in the presence of water ⇒ suspended in
non-aqueous vehicles. Examples are phenoxymethypencillin/
coconut oil and tetracycline HCL/ oil
3) To mask the taste:
Examples are paracetamol suspension (more palatable) and
chloramphenicol palmitate.
4) Some materials are needed to be present as finely divided forms to
increase the surface area. Fore example, Mg carbonate and Mg
trisilcate are used to adsorb some toxins
5) Suspension can be used topical applications:
An example is calamine lotion Bp ⇒ after evaporation of dispersing
media; the active agent will be left as light deposit
6) Can be used for parentral administration ⇒ intramuscular (i.m.) to
control arte of absorption
7) In vaccines
3
Aluminum hydroxide
Absorbed antigen
Aluminum hydroxide
Absorbed antigen
e.g. Diphtheria and Tetanus vaccines
4. 8) X-ray contrast media: an example is oral and rectal administration of
propyliodone
9) In aerosol ⇒ suspension of active agents in mixture of propellants
Qualities of ideal suspension: A well-formulated suspension should have
the following properties:
1) The dispersed particles should not settle readily and the settle should
redispersed immediately on shacking. Ideally, the particles in a
suspension should not sediment at any time during the storage
period. Unfortunately, the present technology does not allow us to
prepare such a suspension. Since one cannot completely avoid the
sedimentation of particles, it is desirable that the particles should
settle slowly. The easy redispersion of sedimented particles in a
suspension is important for the uniformity of dose.
2) The particle should not form a cake on settling
3) The viscosity should be such that the preparation can be easily
poured. A highly viscous suspension would make pouring difficult.
4) It should be chemically and physically stable
5) It should be palatable (orally)
6) It should be free from gritting particles (external use)
FACTORS TO BE CONSIDERED
A- Wetting of the particles:
4
Suspending
media
Solid
particles Hydrophilic can be
dispersed easily
Difficult to disperse and
float on the surface due to
hydrophobic surface or
entrapped air
Suspending
media
Solid
particles Hydrophilic can be
dispersed easily
Difficult to disperse and
float on the surface due to
hydrophobic surface or
entrapped air
5. • It is difficult to disperse solid particles in a liquid vehicle due to the
layer of adsorbed air on the surface. Thus, the particles, even high
density, float on the surface of the liquid until the layer of air is
displaced completely. The use of wetting agent allows removing
this air from the surface and to easy penetration of the vehicle into
the pores. Alcohol, glycerin, and propylene glycol are frequently
used to remove adsorbed air from the surface of particles when
aqueous vehicle is used to disperse the solids. When the particles
are dispersed in a non-aqueous vehicle, mineral oil is used as
wetting agent. Irrespective of the method of preparation, the solid
particles must be wetted using any of the suitable wetting agents
before the dispersion in the vehicle.
• Solid particles that are not easily wetted by aqueous vehicle after
the removable of the adsorbed air are referred to as hydrophobic
particles. It is necessary to reduce the interfacial tension between
the particles and the vehicle by using surface-active agents to
improve the wettibility. Sodium lauryl sulfate is one of the most
commonly used surface-active agents. Hydrophilic particles are
easy to disperse in the aqueous vehicle once the adsorbed air is
removed. Hydrophilic particles do not require the use of surface-
active agents.
5
6. • The main function of wetting agents: (1)- to reduce the contact
angle between surface of solid particles and wetting liquid via
displace the air in the voids (2)- surfactant
• Examples of wetting agents are tragcanth mucilage, glycerin,
glycols, bentonite and polysorbates.
• Excessive amounts of wetting agents can cause foaming or
undesirable taste or odor.
• Contact angle can be used to measure wettibility, if the angle
approximately equal or more than 90 0
, particles are floating well
out of fluid.
B-Particle size:
• Particle size of any suspension is critical and must be reduced within
the range as determined during the preformulation study.
• Too large or too small particles should be avoided. Larger particles
will settle faster at the bottom of the container and too fine particles
will easily form hard cake at the bottom of the container.
• The particle size can be reduced by using mortar and pastel but in
large-scale preparation different milling and pulverization
equipments are used.
• Limitation in particle size reduction (after reaching a certain particle
size):
1. Expensive and time consuming
2. Movement of small particles due to brownian motion cause
particles to aggregate, settle, form hard cake that it is
difficult to redispersed
6
7. C-Sedimentation:
• Sedimentation of particles in a suspension is governed by several
factors: particle size, density of the particles, density of the vehicle,
and viscosity of the vehicle. The velocity of sedimentation of particles
in a suspension can be determined by using the Stoke's law:
Where:
v = velocity of sedimentation
d = diameter of the particle
g = acceleration of gravity
ρ1 = density of the particle
ρ2 = density of the vehicle
η = viscosity of the vehicle
• According to the Stoke's equation, the velocity of sedimentation of
particles in a suspension can be reduced by decreasing the particle
size and also by minimizing the difference between the densities of
the particles and the vehicle. Since the density of the particles is
constant for a particular substance and cannot be changed, the
changing of the density of the vehicle close to the density of the
particle would minimize the difference between the densities of the
particles and the vehicle. The density of the vehicle of a suspension
can be increased by adding the following substances either alone or
in combination: polyethylene glycol, polyvinyl pyrolidone, glycerin,
sorbitol, and sugar.
7
v =
d2 (p1-p2) g
18 η
v =
d2 (p1-p2) g
18 η
8. • The viscosity of the vehicle also affects the velocity of sedimentation.
It decreases as the viscosity of the vehicle increases. The viscosity
and density of any vehicle are related to each other, so any attempt
to change one of these parameters will also change the other one.
D-Electrokinetic Properties
• Dispersed solid particles in a suspension may have charge in relation
to their surrounding vehicle. These solid particles may become
charged through one of two situations.
1. Selective adsorption of a particular ionic species present in the
vehicle. This may be due to the addition of some ionic species
in a polar solvent. Consider a solid particle in contact with an
electrolyte solution. The particle may become positively or
negatively charged by selective adsorption of either cations or
anions from the solution.
2. Ionization of functional group of the particle. In this situation,
the total charge is a function of the pH of the surrounding
vehicle.
8
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
++
+ +
-
-
-
-
-
-
-
-
-
-
-
-
-
- -
--
-
-
-
-
-
-
- - -
- -
+
-
-
+
a-
a
b-
b
c-
c
d-
d
Tightly
bound
layer
Diffusion
layer
Electro-neutral
region
Surface
Counterion Shear plan
++
++
++
++
++
++
++
++
++
++
++
++
++
++
++
++
++
++
++
++
++
++
++
++
++
++
++
++
++
++
++
++++
++ ++
--
--
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--
--
-- --
----
--
--
--
--
--
--
-- -- --
-- --
++
--
--
++
a-
a
b-
b
c-
c
d-
d
Tightly
bound
layer
Diffusion
layer
Electro-neutral
region
Surface
Counterion Shear plan
9. • In the above figure, the particle is positively charged and the anions
present in the surrounding vehicle are attracted to the positively
charged particle by electric forces that also serve to repel the
approach of any cations. The ions that gave the particle its charge,
cations in this example, are called potential-determining ions.
Immediately adjacent to the surface of the particle is a layer of tightly
bound solvent molecules, together with some ions oppositely
charged to the potential-determining ions, anions in this example.
These ions, oppositely charged to the potential-determining ions, are
called counterions or gegenions. These two layers of ions at the
interface constitute a double layer of electric charge. The intensity of
the electric force decreases with distance from the surface of the
particle. Thus, the distribution of ions is uniform at this region and a
zone of electrolneutrality is achieved.
E-Nernst and zeta potential-
• The difference in electric potential between the actual surface of the
particle and the electroneutral region is referred to as Nernst
potential. Thus, Nernst potential is controlled by the electrical
potential at the surface of the particle due to the potential
determining ions. Nernst potential has little effect in the formulation
of stable suspension.
• The potential difference between the ions in the tightly bound layer
and the electroneutral region, referred to as zeta potential (see the
figure), has significant effect in the formulation of stable suspension.
Zeta potential governs the degree of repulsion between adjacent,
similar charged, solid dispersed particles.
9
10. • If the zeta potential is reduced below a critical value, the force of
attraction between particles succeed the force of repulsion, and the
particles come together. This phenomenon is referred to as
flocculation and the loosely packed particles are called floccule.
F-Deflocculation and flocculation:
• Deflocculation of particles is obtained when the zeta potential is
higher than the critical value and the repulsive forces supersede the
attractive forces.
• The addition of a small amount of electrolyte reduces the zeta
potential. When this zeta potential goes below the critical value, the
attractive forces supersede the repulsive forces and flocculation
occurs.
• The following table illustrates the relative properties of flocculated
and Non-flocculated suspension
10
FLOCCULATED NON-FLOCCULATED
1. Particles forms loose aggregates and
form a network like structure
2. Rate of sedimentation is high
3. Sediment is rapidly formed
4. Sediment is loosely packed and doesn’t
form a hard cake
5. Sediment is easy to redisperse
6. Suspension is not pleasing in appearance
7. The floccules stick to the sides of the
1. Particles exist as separate entities
2. Rate of sedimentation is slow
3. Sediment is slowly formed
4. Sediment is very closely packed and a hard cake
is formed
5. Sediment is difficult to redisperse
6. Suspension is pleasing in appearance
7. They don’t stick to the sides of the bottle
11. • It should be noted that the deflocculated suspensions should be
avoided because of the formation of irreversible solid hard cake.
Although flocculated suspensions sediment faster and form a clear
supernatant, these are easy to redisperse.
• The following figure shows the effect of period of standing on
flocculated and deflocculated suspension:
G-Thixotropic suspension-A thixotropic suspension is the one that is
viscous during storage but loses consistency and become fluid upon
shaking. A well-formulated thixotropic suspension would remain fluid long
enough for the easy dispense of a dose but would slowly regain its original
viscosity within a short time.
Method of preparation
The preparation of suspension includes three methods: (1) use of
controlled flocculation and (2) use of structured vehicle (3)- combination of
both of the two pervious methods. The following is the general guidelines
to suspension formulation:
11
12. A-Structured vehicle
• Structured vehicles called also thickening or suspending agents. They
are aqueous solutions of natural and synthetic gums. These are used
to increase the viscosity of the suspension.
• Methyl cellulose, carboxymethyl cellulose, sodium carboxymethyl
cellulose, acacia, gelatin and tragacanth are the most commonly
used structured vehicle in the pharmaceutical suspensions. These
are non-toxic, pharmacologically inert, and compatible with a wide
range of active and inactive ingredients.
12
Particles
Addition of wetting agent and dispersion medium
Uniform dispersion of deflocculated particles
A
Incorporation of
structured vehicle
Deflocculated suspension
in structured vehicle
as final product
B C
Addition of
flocculating agent
Flocculated suspension
as final product
Addition of
flocculating agent
Flocculated suspension
Incorporation of
structured vehicle
Flocculated suspension
in structured vehicle as
final product
13. • These structured vehicles entrapped the particle and reduces the
sedimentation of particles. Although, these structured vehicles
reduces the sedimentation of particles, not necessarily completely
eliminate the particle settling. Thus, the use of deflocculated
particles in a structure vehicle may form solid hard cake upon long
storage.
• The risk of caking may be eliminated by forming flocculated particles
in a structured vehicle.
• Note that too high viscosity isn’t desirable and it causes difficulty in
pouring and administration. Also, it may affect drug absorption since
they adsorb on the surface of particle and suppress the dissolution
rate.
• Structured vehicles are pseudoplastic or plastic in their rheological
behaviors
• In the following table is summary of suspending agents
13
15. B-Controlled flocculation
• Controlled flocculation of particles is obtained by adding flocculating
agents, which are (1)-electrolytes (2)- surfactants (3)- polymers
Typical Flocculation agents
• Most frequently used flocculating agents are electrolytes, which
reduce the zeta potential surrounding the solid particles. This leads
to decrease in repulsion potential and makes the particle come
together to from loosely arrange structure (floccules).
• The flocculating power increases with the valency of the ions. As for
example, calcium ions are more powerful than sodium ions because
the velency of calcium is two whereas sodium has valency of one.
• The following figure shows the flocculation of a bismuth subnitrate
suspension by means of monobasic potassium phosphate
(flocculating agents).
15
1-Addition of electrolyte to control flocculation
16. • Both ionic and non-ionic surfactants could be used to control
flocculation
• Surfactant adsorbed on the surface of solid particle leading to
neutralization or reversing the surface charge
• Since most of surfactants act as wetting agents and flocculating
agents, the amount of surfactant to be added should be calculated
based on this fact.
16
The particles of bismuth subnitrate are positively charged originally. By addition of electrolyte
(phosphate, -ve) the zeta potential fell down near zero. At this neutralization value noted
absence of caking. Continuing adding of negatively charged electrolyte resulted in changing
the overall zeta potential of particles to negative and formation of cake.
2-Addition of surfactant to control flocculation
17. • Polymers are long-chained, high molecular-weight compounds
containing active groups spaced along their length.
• These agents promote flocculation through adsorption of part of the
chain on the surface of particle and the remaining part project out
into the dispersion medium. Formation of bridge between the
projected parts leads to formation of floccules (see the following
figure)
17
3- Addition of polymers to control flocculation
Example of surfactant used as flocculating agents
Formation of bridge between particles
Projection out into
dispersion medium
Adsorption on the
surface of particles
Solid particle Solid particle
Formation of bridge between particles
Projection out into
dispersion medium
Adsorption on the
surface of particles
Solid particle Solid particle
18. • Hydrophilic polymers also act as protective colloids resulting in
coated particles have fewer tendencies to form cake.
• Polymers exhibits pseudoplastic flow in solution that promotes the
physical stability of suspension
• Some polymers like gelatin stabilize the suspension based on the pH
and ionic strength of dispersion medium (carry charge)
• An example of polymer is xanthan gum
• Positively charged Liposomes (vesicles of phospholipids) adsorbed on
negatively charged particles to prevent caking formation.
B- Flocculation in structured vehicles
• Sometimes suspending agents can be added to flocculated
suspension to retard sedimentation
• Examples of these agents are Carboxymethylcellulose (CMC),
Carbopol 934, Veegum, and bentonite
• It should be noted that physical incompatibility can limit the addition
of suspending agent
18
Most of hydrophilic colloids are negatively charged
-
Compatible Incompatible
-
+
+
+
+
+
Addition of
electrolyte
_
_
_
_
_
_
-
+
+
+
+
+
+
--
-- -
+
-
--
-- -
+
-
Addition of
suspending
agent
_
_
_
_
_
Positively charged
particles
Negatively charged
particles
Particle settle rapidly
Most of hydrophilic colloids are negatively charged
--
Compatible Incompatible
-
+
+
+
+
+
--
+
+
+
+
+
Addition of
electrolyte
__
__
__
__
__
__
-
+
+
+
+
+
--
+
+
+
+
+
++
--
-- -
+
- --
-- -
+-
-- -
+ -- -
++
-
--
-- -
+
- --
-- -
+-
-- -
+ -- -
++
-
Addition of
suspending
agent
__
__
__
__
__
Positively charged
particles
Negatively charged
particles
Particle settle rapidly
19. • Under this circumstance, the formulator can protect particle by
changing sign of particle from negative to positive using protective
colloids. This is illustrated by the following figure:
19
Ready to use suspension and extemporaneous preparation
20. • Ready to use suspension is manufactured as you learn in this class
• Extemporaneous suspension is unordinary preparation that
pharmacist wants to prepare to a water-insoluble drug that exists in
tablet or capsule for situations when liquid dosage from is needed.
The following steps could be done to prepare extemporaneous
suspension:
1. Put the tablet or capsule content in mortar and crush it
2. Add the suspending vehicle slowly with mixing
3. You could add any flavoring agent or coloring agent available
4. Example of ready available suspending agents are Roxanes diluent
and Cologel
Suspensions are evaluated by determining their physical stability. Two
useful parameters for the evaluation of suspensions are sedimentation
volume and degree of flocculation. The determination of sedimentation
volume provides a qualitative means of evaluation. A quantitative
knowledge is obtained by determining the degree of flocculation.
1. Sedimentation volume: (F), sedimentation volume of a suspension is
expressed by the ratio of the equilibrium volume of the sediment, Vu, to
the total volume, Vo of the suspension.
F = Vu/Vo
The value of F normally lies between 0 to 1 for any pharmaceutical
suspension. The value of F provides a qualitative knowledge about the
physical stability of the suspension.
20
Evaluation of suspensions
21. F= 1 No sedimentation, no clear
supernatant
F =0.5 50% of the total volume is occupied
by sediment
F > 1 Sediment volume is greater than the
original volume due to formation of
floccules which are fluffy and loose
2. Degree of flocculation: (ß), degree of flocculation is the ratio of the
sedimentation volume of the flocculated suspension, F, to the
sedimentation volume of the deflocculated suspension, F∞
ß = F / F∞
21
22. (Vu/Vo) flocculated
ß = --------------------
(Vu/Vo) deflocculated
When the total volume of both the flocculated and the deflocculated
suspensions are same; the degree of flocculation, ß = (Vu)floc/(Vu)defloc .The
minimum value of ß is 1; this is the case when the sedimentation volume of
the flocculated suspension is equal to the sedimentation volume of
deflocculated suspension. ß is more fundamental parameter than F since it
relates the volume of flocculated sediment to that in a deflocculated
system
Rheological consideration: viscosity of suspension affects and controls the
settling of dispersed particle. It, also, affects pouring the product from
bottle and spreading qualities in case of lotion. Best viscosity for suspension
is to be high during storage to prevent sedimentation and to be low at high
shear to ease the administration. Thus, pseudoplastic/ thixotrpic and
plastic/ thixotropic suspending agents could be use for this purpose.
Combination of two suspending agents can enhance the stability of
suspension
Ingredients of suspension:
22
7. Active ingredient
8. Wetting agent
9. Suspending agent
10.Flocculated agent
1. Preservative
2. Buffer system
3. Color agent
4. Flavor agent
23. Typical buffering agents, flavors, colorants, and preservative used in
suspensions:
Packaging and Storage of Suspensions:
1) Should be packaged in wide mouth containers having adequate air space
above the liquid.
2) Should be stored in tight containers protected from: freezing, excessive
heat & light
3) Label: "Shake Before Use" to ensure uniform distribution of solid
particles and thereby uniform and proper dosage.
4) Stored in room temperature if it is dry powder (25 0
C). It should be
stored in the refrigerator after opening or reconstitute (freezing should be
avoided to prevent aggregation)
23
Buffer
Flavor
Ammonia solution
Citric acid
Fumaric acid
Sodium citrate
Cherry
Grape
Methyl salicylatte
Orange
Peppermint
Class Agent
24. A-Physical stability:
B-Chemical stability:
24
Stability of suspension
1. Appearance, color, odor and taste
2. pH
3. Specific gravity
4. Sedimentation arte
5. Sedimentation volume
6. Zeta potential measurement
7. Compatibility with container
1. Degradation of active ingredient
2. Viscosity change
3. antimicrobial activity:
a. Incompatibility with preservative