ABSTRACT
This chapter focuses on the usefulness of emulsion systems for the delivery of water-insoluble compounds for parenteral administration. Emulsions for parenteral use should have droplet size less than 1 µ m, and hence are often called submicron emulsions, or microemulsion. A typical parenteral oil-in-water (o/w) emulsion is composed of lipid droplets, emulsifier, and osmotic agent; it is administered by either intravenous (IV) bolus or IV infusion. Surfactants are commonly used to stabilize the emulsion by reducing interfacial tension between the oil and the water phases. The hydrophilic– lipophilic balance classification system was first introduced by W. C. Griffin to characterize the relative affinity of a surfactant to the aqueous and oil phase. Preparation of an emulsion requires mixing the two immiscible phases with the surfactant and applying energy to create shear forces to deform the interface and form droplets, using sufficient force and time to achieve the required droplet size. Drug-emulsion formulations can be used for solubilization and delivery of pharmaceutical compounds.
