Estimation of biliary excretion of ureidopenicillins in healthy volunteers using marker dilution technique.

1 Aspiration of duodenal fluid and estimation of recovery by a marker dilution technique was adapted to measure the biliary excretion of two chemically related ureidopenicillins, mezlocillin and azlocillin, in healthy volunteers. 2 The drug was infused intravenously at a constant rate over a period of 6 h during which duodenal fluid was aspirated through the distal opening of a triple-lumen polyvinyl tube. 3 Drug levels in plasma, urine and duodenal fluid were determined by h.p.l.c. 4 Biliary excretion rate was calculated by multiplying the concentration in the duodenal fluid by the dilution factor resulting from the dilution of marker substance infused through the proximal opening of the triple-lumen tube. 5 Since the results obtained by the marker dilution technique are comparable to data obtained by studies in patients with t-tube drainage following biliary surgery, it can be concluded that the method is useful to measure the biliary excretion of drugs in man.