The inhibitory effect of zinc pyrithione on the epidermal proliferation of animal skins.

The hypothesis that zinc pyrithione, a highly active anti-dandruff agent, exerts an anti-biosynthetic effect and reduces the epidermal turnover has been tested using guinea pig and hairless mouse skins. It has been found that enhanced mitosis caused by both stripping off the horny layers and sodium dodecyl sulphate, could be suppressed by approximately 50% by the topical application of zinc pyrithione. Furthermore, sodium dodecyl sulphate-induced epidermal hyperproliferation has been found suppressible by the simultaneous application of zinc pyrithione. Thymidine incorporation studies using hairless mice revealed that a single application of zinc pyrithione results in reduction of DNA synthesis. It is suggested that the anti-dandruff effect of zinc pyrithione results primarily from its action as an anti-biosynthetic agent rather than from its anti-yeast action.