Review of orthostatic tests on the safety of tamsulosin, a selective alpha(1A)-adrenergic receptor antagonist, shows lack of orthostatic hypotensive effects

Two phase III studies with tamsulosin, a selective alpha (1A)-adrenergic re ceptor antagonist, were conducted to evaluate the safety and efficacy of th e standard treatment doses of 0.4 mg/day and 0.8 mg/day in patients with sy mptoms of benign prostatic hyperplasia (BPH). These large-scale clinical tr ials were the first to include extensive testing for possible drug-induced orthostatic hypotension (OH). The frequency of positive orthostatic tests a nd magnitude of vital sign changes were compared among tamsulosin and place bo-treated groups. The results indicate that tamsulosin up to 0.8 mg/day do es not induce higher risk of OH than that of placebo. Data from post-market ing surveillance (PMS) studies of tamsulosin indicate that the incidence of hypotension and syncope is extremely low in community-dwelling elderly men treated for BPH. From the results of the phase III studies, PMS studies an d an active-controlled clinical pharmacology study, we conclude that the or thostatic test is a useful and convenient method to evaluate the risk of OH and syncope during the investigational stage.