The effect of the vehicle formulation on the stratum corneum penetration characteristics of clobetasol 17-propionate in vivo.

The multiple skin surface biopsy technique to measure stratum corneum (SC) penetration characteristics in vivo has been more accurately quantified and used to provide information on the kinetics of transfer of a topical steroid through the SC. Radiolabelled clobetasol 17-propionate formulated in two different vehicles, consisting primarily of dibutyl adipate or of propylene glycol, was applied and the penetration characteristics compared. Using exponential expressions for radioactivity in skin surface biopsies as a function of SC depth, and total SC radioactivity as a function of time, a mathematical model was developed to calculate the rate of loss of steroid through superficial shedding and the rate of transfer of steroid from the SC into the epidermis. When a topical steroid was applied for 8 h under gauze occlusion, over 80% was recovered from the gauze.