Bile rifaximin concentration after oral administration in patients undergoing cholecystectomy.

Rifaximin, a new antibiotic derived from rifamycin SV, was measured in the cholecystic bile of 13 patients submitted to cholecystectomy, after oral administration of 1600 mg of the drug in the 48 hour preceding surgery. Rifaximin concentrations were quantified only in 6 patients and were at least five times lower than those detected with rifampicin, under similar experimental conditions. Results seem to indicate that rifaximin is virtually not absorbed through the intestinal mucosa after oral administration.