Observations on the Role of Vehicles in Percutaneous Penetration

Abstract

A previous study in this series¹ examined the relation between the vehicle and the relative rate of diffusion to the skin surface of an incorporated substance. The present investigation concerns the effect of the vehicle on the percutaneous penetration of substances known to penetrate human skin. The Vehicles Vehicles were previously classified as (1) oil-in-water emulsion, (2) aqueous, (3) water-in-oil emulsion, (4) grease, and (5) nonvolatile water-miscible. An example of each type was used in this study, with the exception of an aqueous vehicle. Rapid evaporation and subsequent concentration of incorporated substances make an aqueous vehicle unsuitable for this study. An anhydrous water-in-oil emulsion was included for the investigation of several specific points. The oil-in-water emulsions were conpounded to meet the requirements thought necessary for a series of test vehicles. Two are included, since all of the drugs studied were not compatible with any one. The