Percutaneous absorption of the 21-β-benzoylamino iso-butyrate of triamcinolone acetonide by rats and rabbits

The percutaneous absorption of the β-benzoylaminoisobutyrate of [³H]-triamcinolone acetonide (TBI) has been studied in rats and rabbits. Up to about 5% and 20% of the applied dose was absorbed by rats and rabbits respectively during 5 days. In both species, absorption was mainly complete after about 3 days, although most of the dose was still present at the site of application. Of the absorbed radioactivity, the rat excreted about 1% and 2% of the dose respectively in the urine and faeces and the rabbit 9% and 4% respectively in 5 days. Peak plasma concentrations of drug equivalents occurred in rats at about 48 h (1.9 ng/ml) and in rabbits at about 72 h (2.6 ng/ml).