Abstract
Serum levels of etretinate (ET) and the active metabolite (AM) were monitored during and after the administration to 12 patients with disorders of keratinization and who were treated with ET. There were differences in serum levels of ET and AM among the patients at the point of the appearance or disappearance of side effects of the drug. However, the serum levels of ET and AM were always lower at the point of disappearance than at the point of appearance of the side effects. The drug and the active metabolite were slowly eliminated into the serum after cessation of the administration, and the maximal durations of the elimination of ET and AM were about 3 and 6 months, respectively.
