Single Dose Crossover Study to Evaluate the Absolute Bioavailability of a Sustained-Release Formulation of Bunazosin (E1015) in Healthy Male Volunteers

Abstract

An open-label randomised crossover study was undertaken to investigate the pharmacokinetics of intravenous bunazosin, and to determine the absolute bioavailabilities of the standard and sustained-release tablet formulations of the drug. 12 healthy volunteers received a 10-minute intravenous infusion of bunazosin 1mg, 2 conventional sugar-coated bunazosin 1mg tablets, and a sustained-release bunazosin 6mg tablet under fasting conditions. Plasma bunazosin concentrations declined in a biexponential manner following intravenous drug administration, and similar terminal elimination half-lives (≈ 2 hours) were observed with intravenous bunazosin and the conventional tablet. The absolute bioavailabilities of the conventional and sustained-release tablet formulations of bunazosin were 44.1 ± 7.7 and 44.6 ± 10.6%, respectively (mean ± SD).