Dose-dependent bioavailability of amoxycillin.

Amoxycillin bioavailability at four different dose levels was studied. Healthy volunteers participated in the experiments. They received in separate occasions a single 250 mg, 500 mg, 750 mg and 1 g doses of the antibiotic. Amoxycillin was assayed in the urine by microbiological method. The mean urinary recovery of amoxycillin was 59.6%, 55.9%, 58.5% and 45.8% of the given dose for the 250 mg, 500 mg, 750 mg and 1 g dose, respectively. Relative amoxycillin bioavailability was determined comparing the total amount of antibiotic excreted unchanged at 24 h of each dose to the 250-mg dose.