Plasma concentrations after three different doses of topical isotretinoin

The aim of the study was to investigate the plasma concentrations of isotretinoin and its metabolites, at three doses and after single and multiple topical applications of isotretinoin gel (0.05%) in hairless rats. We used a highly sensitive HPLC method for simultaneous determinations of these compounds, with a detection limit of 2 ng/ml in plasma. Isotretinoin and its metabolites were detected after single and multiple cutaneous applications of overdosing (2,000 mg) of isotretinoin gel up to 24 h after the single dose and after the last dose. The plasma concentrations of these compounds were below the limit of quantification in all the animals at all times for the 200- and 20-mg doses.