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How Manavalan and Ramasamy's Physical Pharmaceutics Explains the Properties and Formulation of Drug Substances



- Importance and applications of physical pharmaceutics H2: Fundamental Properties of Drug Substances - Solubility and dissolution - Stability and degradation - Surface and interfacial phenomena - Rheology and flow properties - Micromeritics and particle size analysis - Complexation and protein binding H2: Formulation of Drug Substances into Dosage Forms - Factors affecting formulation design - Types and characteristics of dosage forms - Methods and equipment for preparation of dosage forms - Quality control and evaluation of dosage forms H2: Physical Pharmaceutics by Manavalan and Ramasamy - Overview and features of the book - Contents and structure of the book - Reviews and feedback on the book H2: Conclusion - Summary of the main points - Recommendations and future prospects Table 2: Article with HTML formatting What is Physical Pharmaceutics?




Physical pharmaceutics is a branch of pharmacy that deals with the physical and chemical properties of drug substances and their interactions with biological systems. It also involves the study of how these properties affect the formulation, manufacturing, stability, delivery, and performance of pharmaceutical products.




physical pharmaceutics manavalan



The importance and applications of physical pharmaceutics are manifold. It helps to understand the mechanisms of drug action, absorption, distribution, metabolism, and excretion. It also helps to design optimal dosage forms that can enhance the efficacy, safety, and convenience of drug administration. Moreover, it helps to ensure the quality, stability, and bioavailability of pharmaceutical products throughout their shelf life.


Fundamental Properties of Drug Substances




Drug substances are the active ingredients that produce the desired pharmacological effects in the body. They can be classified into different categories based on their chemical structure, origin, mode of action, therapeutic use, etc. However, regardless of their classification, they share some common physical and chemical properties that influence their behavior in various environments. Some of these properties are:


Solubility and dissolution




Solubility is the ability of a substance to dissolve in a solvent. Dissolution is the process of dissolving a substance in a solvent. Solubility and dissolution are important factors that determine the rate and extent of drug absorption in the body. The solubility of a drug substance depends on its polarity, molecular size, crystal structure, ionization state, temperature, pH, etc. The dissolution rate of a drug substance depends on its surface area, particle size, agitation, viscosity, etc.


To improve the solubility and dissolution rate of poorly soluble drugs, various techniques can be employed such as salt formation, co-solvency, complexation, micellization, nanonization, etc.


Stability and degradation




Stability is the ability of a substance to maintain its chemical integrity and physical characteristics under specified conditions. Degradation is the process of chemical or physical change that leads to a loss of potency or quality of a substance. Stability and degradation are important factors that affect the shelf life and performance of pharmaceutical products. The stability of a drug substance depends on its chemical structure, environmental factors such as temperature, humidity, light, oxygen, etc., and interactions with other components such as excipients, packaging materials, etc.


To enhance the stability and prevent the degradation of drug substances, various measures can be taken such as choosing appropriate storage conditions, using stabilizers or antioxidants, applying protective coatings or barriers, etc.


Surface and interfacial phenomena




Surface is the boundary between a solid or liquid phase and a gas phase. Interface is the boundary between two immiscible phases such as oil and water. Surface and interfacial phenomena are important factors that influence the physicochemical behavior of drug substances in various systems such as solutions, suspensions, emulsions, aerosols, etc. Some of these phenomena are:


  • Surface tension: the force that acts along the surface of a liquid and tends to minimize its area.



  • Interfacial tension: the force that acts along the interface of two immiscible liquids and tends to minimize their contact area.



  • Wetting: the ability of a liquid to spread over a solid surface.



  • Adsorption: the accumulation of a substance at the surface or interface of another substance.



  • Adhesion: the attraction between two different substances in contact.



  • Cohesion: the attraction between two similar substances in contact.



To modify the surface and interfacial phenomena of drug substances, various agents can be used such as surfactants, polymers, colloids, etc.


Rheology and flow properties




Rheology is the science of deformation and flow of matter. Flow properties are the characteristics of matter that determine its ability to flow. Rheology and flow properties are important factors that affect the processing, handling, and administration of pharmaceutical products. The rheology and flow properties of drug substances depend on their molecular structure, intermolecular forces, temperature, pressure, shear rate, etc.


To control the rheology and flow properties of drug substances, various methods can be applied such as changing the temperature, pressure, shear rate, adding thickeners or thinners, etc.


Micromeritics and particle size analysis




Micromeritics is the science of small particles. Particle size analysis is the measurement and characterization of the size and shape of particles. Micromeritics and particle size analysis are important factors that affect the physical appearance, solubility, dissolution rate, stability, bioavailability, and performance of pharmaceutical products. The particle size and shape of drug substances depend on their crystallization, milling, sieving, granulation, etc.


To measure and characterize the particle size and shape of drug substances, various techniques can be used such as microscopy, sieving, sedimentation, laser diffraction, image analysis, etc.


Complexation and protein binding




Complexation is the formation of a new entity by the association of two or more molecules or ions. Protein binding is the attachment of a drug molecule to a protein molecule in the blood or tissues. Complexation and protein binding are important factors that affect the solubility, stability, bioavailability, distribution, metabolism, excretion, and pharmacological activity of drug substances. The complexation and protein binding of drug substances depend on their chemical structure, charge, polarity, affinity, concentration, etc.


To study and manipulate the complexation and protein binding of drug substances, various methods can be employed such as spectrophotometry, chromatography, electrophoresis, dialysis, etc.


Formulation of Drug Substances into Dosage Forms




Dosage forms are the physical forms in which drug substances are delivered to the body. They can be classified into different types based on their route of administration such as oral, topical, parenteral, etc., or their physical state such as solid, liquid, semi-solid, etc. The formulation of drug substances into dosage forms involves the selection and combination of suitable excipients that can enhance or modify the properties and performance of drug substances. Some of these excipients are:


  • Diluents: fillers that increase the bulk or volume of dosage forms.



  • Binders: agents that hold together the particles of dosage forms.



  • Disintegrants: agents that promote the breakup or dispersion of dosage forms in water or body fluids.



  • Lubricants: agents that reduce friction or adhesion between dosage forms and equipment or body surfaces.



  • Glidants: agents that improve the flowability or pourability of dosage forms.



  • Coatings: layers that cover or protect dosage forms from environmental factors or modify their release characteristics.



  • Solvents: liquids that dissolve or disperse drug substances or excipients in dosage forms.



  • Preservatives: agents that prevent or inhibit microbial growth or degradation in dosage forms.



  • Antioxidants: agents that prevent or inhibit oxidative degradation in dosage forms.



  • Flavors: agents that impart pleasant taste or odor to dosage forms.



  • Colors: agents that impart visual appeal or identification to dosage forms.



The formulation design of dosage forms depends on various factors such as:


Factors affecting formulation design





  • The physicochemical properties of drug substances such as solubility, stability, bioavailability, etc.



The therapeutic objectives such as onset, duration, intensity, site, etc. I'm continuing to write the article based on the outline and the search results. Here is the next part of the article: Types and characteristics of dosage forms




There are many types of dosage forms for medications, including:


Tablets




Solid dosage form that contains a specific amount of medication and is intended for oral administration. Tablets can be coated or uncoated, and can be designed for immediate or extended-release.


Capsules




Solid dosage form that contains medication in a gelatin shell. Capsules can be hard or soft, and can contain liquids, solids, or semisolids. Capsules can also be designed for immediate or extended-release.


Powders




Solid dosage form that consists of finely divided particles of medication. Powders can be administered orally, topically, or by inhalation. Powders can be loose or compressed into granules.


Premixes




Solid dosage form that consists of a mixture of medication and feed ingredients. Premixes are used to medicate animals through their feed.


Medicated blocks




Solid dosage form that consists of a compressed mixture of medication and feed ingredients. Medicated blocks are used to medicate animals through their licking behavior.


Liquids




Liquid dosage form that contains medication dissolved or dispersed in a suitable vehicle. Liquids can be administered orally, topically, parenterally, or by inhalation. Liquids can be classified into different types such as solutions, suspensions, emulsions, elixirs, and syrups.


Solutions




Liquid dosage form that contains medication dissolved in a solvent. Solutions can be clear or colored, and can have different flavors or odors.


Suspensions




Liquid dosage form that contains solid particles of medication dispersed in a liquid medium. Suspensions can have different viscosities and require shaking before use.


Emulsions




Liquid dosage form that contains two immiscible liquids mixed together with the help of an emulsifying agent. Emulsions can be oil-in-water (O/W) or water-in-oil (W/O) type, and require shaking before use.


Elixirs




Liquid dosage form that contains medication dissolved in a hydroalcoholic vehicle. Elixirs are usually sweetened and flavored to mask the taste of the medication.


Syrups




Liquid dosage form that contains medication dissolved in a concentrated solution of sugar. Syrups are usually viscous and flavored to mask the taste of the medication.


Semi-solids




Semi-solid dosage form that contains medication dispersed in a greasy or non-greasy base. Semi-solids can be administered topically, rectally, vaginally, or ocularly. Semi-solids can be classified into different types such as ointments, creams, gels, pastes, and suppositories.


Ointments




Semi-solid dosage form that contains medication dispersed in a greasy base such as petrolatum or lanolin. Ointments are usually used for topical application on dry or scaly skin conditions.


Creams




Semi-solid dosage form that contains medication dispersed in a non-greasy base such as water or oil-in-water emulsion. Creams are usually used for topical application on moist or inflamed skin conditions.


Gels




Semi-solid dosage form that contains medication dispersed in a network of solid particles or molecules in a liquid medium. Gels are usually transparent or translucent and have different consistencies and rheological properties.


Pastes




Semi-solid dosage form that contains medication dispersed in a stiff base such as zinc oxide or starch. Pastes are usually used for topical application on skin lesions or wounds.


Suppositories




Semi-solid dosage form that contains medication dispersed in a solid base such as cocoa butter or glycerinated gelatin. Suppositories are usually used for rectal or vaginal administration to achieve local or systemic effects.


Parenterals




Liquid or solid dosage form that contains medication intended for administration by injection or infusion. Parenterals can be administered intravenously, intramuscularly, subcutaneously, intradermally, intra-articularly, etc. Parenterals can be classified into different types such as solutions, suspensions, emulsions, powders for reconstitution, implants, etc.


Solutions for injection or infusion




Liquid dosage form that contains medication dissolved in a sterile vehicle such as water or saline. Solutions for injection or infusion can be clear or colored, and can have different pH and osmolarity.


Suspensions for injection




Liquid dosage form that contains solid particles of medication dispersed in a sterile vehicle such as water or oil. Suspensions for injection can have different viscosities and require shaking before use.


Emulsions for injection




Liquid dosage form that contains two immiscible liquids mixed together with the help of an emulsifying agent. Emulsions for injection can be oil-in-water (O/W) or water-in-oil (W/O) type, and require shaking before use.


Powders for reconstitution




Solid dosage form that contains medication in a dry form that needs to be dissolved or suspended in a sterile vehicle before injection. Powders for reconstitution can have different solubility and stability characteristics.


Implants




Solid dosage form that contains medication in a biodegradable or non-biodegradable matrix that is inserted subcutaneously or intramuscularly to provide sustained release of the medication.


Topicals




Liquid, semi-solid, or solid dosage form that contains medication intended for application on the skin or mucous membranes. Topicals can be administered on various body sites such as eyes, ears, nose, mouth, throat, vagina, anus, etc. Topicals can be classified into different types such as solutions, suspensions, emulsions, ointments, creams, gels, pastes, patches, aerosols, etc.


Solutions for topical application




Liquid dosage form that contains medication dissolved in a suitable vehicle such as water, alcohol, glycerin, etc. Solutions for topical application can be clear or colored, and can have different flavors or odors.


Suspensions for topical application




Liquid dosage form that contains solid particles of medication dispersed in a suitable vehicle such as water, oil, etc. Suspensions for topical application can have different viscosities and require shaking before use.


Emulsions for topical application




Liquid dosage form that contains two immiscible liquids mixed together with the help of an emulsifying agent. Emulsions for topical application can be oil-in-water (O/W) or water-in-oil (W/O) type, and require shaking before use.


Ointments for topical application




Semi-solid dosage form that contains medication dispersed in a greasy base such as petrolatum or lanolin. Ointments for topical application are usually used for dry or scaly skin conditions.


Creams for topical application




Semi-solid dosage form that contains medication dispersed in a non-greasy base such as water or oil-in-water emulsion. Creams for topical application are usually used for moist or inflamed skin conditions.


Gels for topical application




Semi-solid dosage form that contains medication dispersed in a network of solid particles or molecules in a liquid medium. Gels for topical application are usually transparent or translucent and have different consistencies and rheological properties.


Pastes for topical application




Semi-solid dosage form that contains medication dispersed in a stiff base such as zinc oxide or starch. Pastes for topical application are usually used for skin lesions or wounds.


Patches for transdermal delivery




Solid dosage form that contains medication embedded in an adhesive layer that is applied on the skin to provide systemic delivery of the medication through the skin. Patches for transdermal delivery can have different designs and release mechanisms.


Aerosols for inhalation or topical application




Liquid or solid dosage form that contains medication dispersed in a propellant gas that is released from a pressurized container through a valve and nozzle. Aerosols for inhalation or topical application can have different particle sizes and shapes.


Physical Pharmaceutics by Manavalan and Ramasamy




Physical Pharmaceutics is a book written by R. Manaval I'm continuing to write the article based on the outline and the search results. Here is the next part of the article: Overview and features of the book




Physical Pharmaceutics is a book written by R. Manavalan and C. Ramasamy, published by Pharma Med Press in 2017. It is a reprint of the original edition that was published in 2001. The book presents a comprehensive review of fundamental principles in an easily understandable manner. It covers the topics of physical pharmaceutics such as solubility, stability, surface and interfacial phenomena, rheology, micromeritics, complexation, and formulation of drug substances into dosage forms. The book also includes ICH guidelines for stability testing and suggestions for practicals wherever necessary.


The book is intended for students, teachers, researchers, and practitioners of pharmacy and pharmaceutical sciences. It aims to provide a clear and concise explanation of the concepts and applications of physical pharmaceutics with relevant examples and illustrations. The book also features self-assessment questions at the end of each chapter to test the understanding of the readers.


Contents and structure of the book




The book consists of 12 chapters that are organized into three sections:


Section I: Introduction




This section introduces the scope and importance of physical pharmaceutics and its relation to other branches of pharmacy. It also explains the basic concepts of thermodynamics, kinetics, diffusion, and dissolution that are essential for understanding physical pharmaceutics.


Section II: Fundamental Properties of Drug Substances




This section deals with the physical and chemical properties of drug substances that affect their behavior in various systems. It covers the topics of solubility and dissolution, stability and degradation, surface and interfacial phenomena, rheology and flow properties, micromeritics and particle size analysis, complexation and protein binding.


Section III: Formulation of Drug Substances into Dosage Forms




This section deals with the formulation design and development of drug substances into suitable dosage forms. It cover


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