ABSTRACT
Injectable dispersed systems (emulsions, suspensions, liposomes, and microspheres) have unique properties, that are related to their size, interfacial area, and dispersion state. The physicochemical principles governing their behavior include thermodynamics, interfacial chemistry, and mass transport. The stability of these dosage forms is a major issue and is a function of thermodynamics, interfacial chemistry, and particle size. Drug release from such systems is governed by mass transport principles, interfacial chemistry, and size.
Principles of thermodynamics and interfacial chemistry as applied to dispersed systems are detailed in this chapter. Although the principles of particle size are discussed here, they are reviewed in greater detail in the chapter by Jiao and Burgess on characterization. Due to the unique factors associated with release of drugs from the different dispersed system dosage forms mass transport issues are addressed in the individual dosage form (suspensions, emulsions, liposomes, and microspheres) chapters.
