Urinary excretion kinetics for evaluation of drug absorption. III. Method for calculation of absorption rate and application to tetracycline absorption in humans.

Abstract

A method was developed to calculate drug absorption rate from urinary excretion rate measurements and applied to study tetracycline absorption in humans after oral ingestion of 25, 50, 100, and 200-mg. doses. Calculation of absorption rate indicated that this drug was absorbed at a rate of about 100 to 140 mg./hr., one hour after 200-mg. doses, and at about 20 to 30 mg./hr., one hour later. Rates at these times decreased when the dose was reduced. Wide individual variation in absorption rate was observed among members of the test panel.