Skin penetration by 2,4-diaminoanisole in the rat

The absorption of 14C-labelled 2,4-diaminoanisole together with its reaction products was investigated after application to the skin of rats. 2,4-Diamino[14C]anisole was applied as an ingredient of three different hair-dyeing formulations using procedures approximating to realistic conditions of use. Percutaneous absorption of the compound ranged from 0.26 to 1.1% of the administered dose, according to the formulation used. Elimination occurred mainly in the urine, with a smaller proportion in the faeces. Very small amounts were detected in the expired air. Complementary investigations involving subcutaneous or oral application of a solution of 2,4-diamino[14C]anisole.2HCl showed that radioactivity was rapidly eliminated in the urine and faeces. Biliary excretion was demonstrated after oral administration.