Kinetics and absolute bioavailability of atenolol

Abstract

Twelve healthy volunteers received four single doses of atenolol (25-, 50-, and 100-mg oral solutions and a 50-mg intravenous infusion), each dose separated by at least one week. Blood and urine assayed for atenolol by a high pressure liquid chromatography (HPLC) method. Kinetic analysis of the intravenous data indicates a three-compartment model with elimination from the central compartment. The mean (+/- SD) terminal elimination half-life is 6.06 +/- 2.02 hr, the mean volume of the central compartment is 0.173 L/kg, and 94.1 +/- 8.0% of the intravenous dose is excreted in the urine. The mean value of the plasma clearance is 10.7 +/- 1.27 L/hr and of the renal plasma clearance, 10.4 +/- 1.14 L/hr. The mean absolute bioavailability for the 25-, 50-, and 100-mg oral doses is 0.52 +/- 0.18, 0.54 +/- 0.12, and 0.58 +/- 0.16, respectively. The maximum plasma concentration varies as a linear function of dose. Time to mean maximum plasma concentration (3.0 hr) and the time for half of the bioavailable dose to be absorbed (2.0 hr) do not differ significantly with dose. The mean renal plasma clearance after oral doses (9.49 +/- 1.6 L/hr) is in the same range as renal clearance after intravenous doses.