Dose-dependent absorption of amoxicillin in patients with an ileostomy.

Amoxicillin was given as single doses of 375, 700, 1500, 3000 and 6000 mg an oral suspension to four volunteers with an ileostomy and with no active intestinal disease after an overnight fast. The excretion of amoxicillin and its penicilloic acid was followed in samples taken from the ileostomy and in urine produced over 6 h. Beta-lactamase activity was measured in ileal fluid and none was found. The percentage of the dose recovered from the ileostomy increased successively from 8% at the lowest dose to 77% at the highest dose. A complementary excretion pattern of amoxicillin was found in the urine, amounting to 70% recovery at the lowest dose to 23% at the highest dose. The results confirm the dose-dependence of the absorption of amoxicillin, which could at least in part be due to specialised absorption of this drug in humans.