330 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS Table V Effects of Keratolytic Agents on Disappearance Time (days) of Dansyl Chloride on Guinea Pig Stratum Corneum WSP SA 6% Sulphur 6% Resorcinol 6% Guinea pig no. (days) (days) (days) (days) 1 11.3 3.6 10.1 8.5 2 10.3 3.1 9.2 8.6 3 10.9 2.0 9.1 10.8 4 11.2 3.0 8.9 8.0 5 10.9 2.8 9.7 7.2 Mean + SD 11.0 + 0.2 2.9 + 0.6** 9.4 + 0.5** 8.6 + 1.3' *, p 0.05 **, p 0.01 compared with WSP (paired t-test). WSP: white soft paraffin. SA: salicylic acid. The mode of action of keratolytic agents on stratum corneum has remained obscure. Salicylic acid, sulphur, and resorcinol all accelerated the desquamation rate of the stratum corneum however, different actions are suggested for the three. Sulphur seems to enhance the rate of desquamation by accelerating cell proliferation in the epidermis, judging from the thickened epidermis. On the other hand, the effect of salicylic acid may be due to a direct action on the intercellular cement substance of the corneocytes because the epidermis was not thickened or irritated. These results indicate that a comparator and a fluorometer are very useful for measuring the turnover time of stratum corneum and for evaluating the effects of keratolytics or cosmetics. .. ! ............ :u'iphu r 6% ..... ..:' !...... iR 'sor:c..inO[ '6,/_' ...... ,.. Figure 8. Histological study of skin from back of guinea pig treated with keratolytic agents for 2 weeks H&E.

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