Galenics of dermal products--vehicles, properties and drug release.
The efficiency, tolerability, and applicability of topical agents are directly related to employed vehicles. Thus to achieve optimum topical therapy, a solid knowledge of the vehicles, their composition, and their physical and dermato-pharmacological actions are important. Common vehicles are complex mixtures consisting of diverse ingredients belonging to six major groups, i. e. hydrophilic and lipophilic bases, emulsifiers, gel-forming agents, preservatives, and antioxidants. This makes it possible to optimize both the cosmetic features and to adjust a vehicle to the properties of an incorporated drug and site of application. On the other hand it makes it difficult to make a proper choice between several alternatives or to use it in individual prescriptions. In order to simplify the selection of a formulation, it is useful to categorize them systemically into several groups, such as ointments, creams, gels, emulsions, and suspensions. Within these groups some general rules can be derived for the selection of a vehicle with respect to skin conditions and the application site. When active substances are incorporated into a base the dermato-biopharmaceutical properties of the whole system (drug + vehicle) also have to be considered. If for a given vehicle drug transport into the skin does not suffice, several methods are described to facilitate its penetration, such as by hydrating the skin or by adding chemical penetration enhancers.
Daniels
Rolf
R
Institute of Pharmaceutical Technology, Eberhard-Karls University, Tübingen, Germany. rolf.daniels@uni-tuebingen.de
Knie
Ulrich
U
D003692:Delayed-Action Preparations / Q000737:chemistry*; D003879:Dermatologic Agents / Q000008:administration & dosage* / Q000737:chemistry*; D004058:Diffusion; D004337:Drug Carriers / Q000737:chemistry*; D004339:Drug Compounding / Q000379:methods*; D004355:Drug Stability; D014677:Pharmaceutical Vehicles / Q000737:chemistry*
D003692:Delayed-Action Preparations; D003879:Dermatologic Agents; D004337:Drug Carriers; D014677:Pharmaceutical Vehicles