A PROSPECTIVE-STUDY IN HEALTHY-VOLUNTEERS OF THE TOPICAL ABSORPTION OF A 5-PERCENT RIFAXIMIN CREAM

Rifaximin, the active ingredient of an antibiotic cream, is a syntheti c antibiotic derived from rifamycin and characterized by minimal absor ption. In animals, no absorption was detected after topical applicatio n on the skin. The question as to whether there is detectable absorpti on in man by the same administration route is answered by this study i n healthy volunteers. One gram oi the cream containing 5% rifaximin wa s massaged on a sizable surface of skin prepared prior to application by mechanical abrasion. Rifaximin concentrations in blood and urine we re then determined by means of HPLC-electrochemical-coulometrical dete ction. Concentrations in all samples being less than 2.5 ng/ml, the me thod's limit of detection, it is concluded that there is no detectable absorption in man. No adverse reactions were reported during this one day study. The results confirm studies performed in animals which sho wed that rifaximin is not absorbed and is well tolerated.