Chapter 13. Surfactants in Pharmaceutical Formulations

Summary

This chapter contains sections titled:

• General Introduction

  • Thermodynamic Consideration of the Formation of Disperse Systems

  • Kinetic Stability of Disperse Systems and General Stabilisation Mechanisms

  • Physical Stability of Suspensions and Emulsions

• Surfactants in Disperse Systems

  • General Classification of Surfactants

  • Surfactants of Pharmaceutical Interest

  • Physical Properties of Surfactants and the Process of Micellisation

  • Size and Shape of Micelles

  • Surface Activity and Adsorption at the Air/Liquid and Liquid/Liquid Interfaces

  • Adsorption at the Solid/Liquid Interface

  • Phase Behaviour and Liquid Crystalline Structures

• Electrostatic Stabilisation of Disperse Systems

  • Van der Waals Attraction

  • Double Layer Repulsion

  • Total Energy of Interaction

• Steric Stabilization of Disperse Systems

  • Adsorption and Conformation of Polymers at Interfaces

  • Interaction Forces (Energies) Between Particles or Droplets Containing Adsorbed Non-ionic Surfactants and Polymers

  • Criteria for Effective Steric Stabilisation

• Surface Activity and Colloidal Properties of Drugs

  • Association of Drug Molecules

  • Role of Surface Activity and Association in Biological Efficacy

  • Naturally Occurring Micelle Forming Systems

• Biological Implications of the Presence of Surfactants in Pharmaceutical Formulations

• Aspects of Surfactant Toxicity

• Solubilised Systems

  • Experimental Methods of Studying Solubilisation

  • Pharmaceutical Aspects of Solubilisation

• Pharmaceutical Suspensions

  • Main Requirements for a Pharmaceutical Suspension

  • Basic Principles for Formulation of Pharmaceutical Suspensions

  • Maintenance of Colloid Stability

  • Ostwald Ripening (Crystal Growth)

  • Control of Settling and Prevention of Caking of Suspensions

• Pharmaceutical Emulsions

  • Emulsion Preparation

  • Emulsion Stability

  • Lipid Emulsions

  • Perfluorochemical Emulsions as Artificial Blood Substitutes

• Multiple Emulsions in Pharmacy

  • Criteria for Preparation of Stable Multiple Emulsions

  • Preparation of Multiple Emulsions

  • Formulation Composition

  • Characterisation of Multiple Emulsions

• Liposomes and Vesicles in Pharmacy

  • Factors Responsible for Formation of Liposomes and Vesicles – The Critical Packing Parameter Concept

  • Solubilisation of Drugs in Liposomes and Vesicles and their Effect on Biological Enhancement

  • Stabilisation of Liposomes by Incorporation of Block Copolymers

• Nano-particles, Drug Delivery and Drug Targeting

  • Reticuloendothelial System (RES)

  • Influence of Particle Characteristics

  • Surface-modified Polystyrene Particles as Model Carriers

  • Biodegradable Polymeric Carriers

• Topical Formulations and Semi-solid Systems

  • Basic Characteristics of Semi-Solids

  • Ointments

  • Semi-Solid Emulsions

  • Gels