ABSTRACT
The broad spectrum of topical preparations in use today vary in their physicochemical nature from powders through semisolids to liquids. While early topical formulations were often crude mixtures of chemicals, the optimized drug delivery systems common today achieve a balance between the physicochemical requisites for stability of active and inactive constituents, preservation against microbial spoilage, and, most importantly, presentation of the drug to the skin in a system that will allow appropriate release of the active to the stratum corneum. This is in addition to ensuring the elegance and user acceptability of the formulation. It is clear, therefore, that topical vehicle formulation is not a facile process, and as many of the desirable properties of the formulation as possible must be fulfilled in this process. Obviously, the synthetic and semisynthetic formulation constituents that are available today make this task somewhat easier than the formulation techniques of yesterday that utilized predominantly natural products.
