Topical bioavailability of a potential anti-acne agent (SC-23110) as determined by cumulative excretion and areas under plasma concentration time curves

The topical bioavailability of a potential anti-acne agent ([14C]-SC-23110) was determined in the rhesus monkey, an animal model relevant to man. By the method of cumulative excretion in urine and feces the percutaneous absorption of 21 microgram/cm2 of the free base form was determined to be 0.58 +/- 0.16 (SD) percent of the applied dose. The mean areas under the plasma concentration time curves (AUC) following topical and intravenous administration were also determined. The ratior of the AUC's following topical and iv administration gave a bioavailability of 0.49% of the applied dose, a value in good agreement with the 0.58% obtained by cumulative excretion. Plasma AUC curves can be used to determined the percutaneous absorption (bioavailability) of compounds. Percutaneous absorption of [14C]-SC-23110 (80 microgram/cm2) when topically applied as the salt or free base form was compared. Twice the amount of compound was absorbed as the free base (0.34%) than as the salt (0.17%).