Drug absorption in patients with T-tube after cholecystectomy.

The influence of bile flow on the absorption of tetracycline, doxycycline, sulphadimidine and cycloserine was studied in 13 volunteer patients with t-tubes in their main bile ducts after biliary surgery. Their hepatic functions and bile flows were estimated by giving I131 radioiodinated rose-bengal intravenously. About 80% radioactive tracer was recovered from the bile when the t-tube was open, so most of the bile was diverted outside the intestinal tract. Up to 4 hours after administration serum tetracycline levels were lower when the t-tube was open than when the t-tube was closed. In one patient the serum levels were so much reduced that therapeutic serum tetracycline levels could not be achieved. The serum doxycycline levels were fairly high and bile flow did not have any effect on absorption. The 24-hour biliary excretion of doxycycline was only about 15% of the urinary excretion. The absorption of sulphadimidine and cycloserine was not affected by the presence or absence of bile. The bile salts are important surfactants in man, and modify the absorption rate of tetracycline, but not of doxycycline, sulphadimidine and cycloserine. Even in the absence of intact bile flow therapeutic serum tetracycline levels can be expected with the doses currently used.