Serum and urinary levels of fentiazac after a single oral and epicutaneous administration in human subjects.

An acute pharmacokinetic investigation was carried out on 6 healthy subjects with 200 mg of epicutaneous 2-phenyl-4-p-chlorophenyl-thiazol-5-ylacetic acid (fentiazac) (5% cream) versus and equivalent dose of oral drug (coated tablets). The two pharmaceutical dosage forms were given to same subjects at a one-week interval according to a cross-over design. The gas chromatographic analysis of the blood and urinary samples allowed to demonstrate that fentiazac is absorbed through the skin. The bioavailability resulting from the epicutaneous administration is markedly lower than that provided by the oral administration. Actually, the coated tablet/cream ratio between the areas under mean serum concentration-time curves amounts to 30:1 approximately. The distribution into the systemic circulation is slow but constant and prolonged; the blood levels remain practically unchanged from 0.5-8 h when a peak begins to be observed; the urinary excretion increases in the course of time and reaches its maximum in the interval between the 12th and 24th h. Vice versa, the renal excretion proves higher in the first 6 h.