Local suppression of sebum secretion in rats by topical cyproterone acetate in ethanol

Sebum production was measured on 2 symmetrically placed areas on the flanks of rats over alternating periods of 18 and 6 hr for 4 days, by absorbing the lipid on pads of cigarette paper held in place by a specially designed harness. Castrated rats receiving testosterone produced about twice as much sebum as untreated littermate controls. Once daily application of ethanol to one flank significantly reduced sebum production, in comparison with the other flank in testosterone-treated but not in untreated rats. Daily application of 5 mg cyproterone acetate in ethanol to one flank in a third group of rats significantly reduced sebum production in comparison with that of the other flank treated with vehicle only. The effects became significant within 24 hr. It seems likely that the sebaceous glands received the topically applied materials by way of the pilo-sebaceous orifices rather than by transepidermal absorption. The results demonstrate that one action of cyproterone acetate is at the target site and suggest that the anti-androgen may be effective when applied topically. The method could prove useful in assessing the local action on sebaceous activity of topically applied substances.