Retention time and concentration in human skin of bifonazole and clotrimazole

The retention time and the extent of penetration in human skin of [14C] labelled bifonazole in comparison to [14C] labelled clotrimazole were investigated in 8 healthy volunteers. In the course of the investigation the backs of the volunteers were treated half with bifonazole, half with clotrimazole which remained on the skin for 24 h. From 24 to 168 h after the administration the skin was stripped with the tear-off strip technique. Three dermal layers of different depth were examined. The results of the examinations revealed, that the quantity of bifonazole that penetrated into the skin was more than twice as high as the quantity of clotrimazole. However, the half-lives and the mean retention times of bifonazole and clotrimazole were nearly similar to each other.