α1-adrenoceptors are widely distributed in the human body and play important physiologic roles. Three α1-adrenoceptor subtypes (α1A, α1B and α1D) have been cloned and show different pharmacologic profiles. In addition, a putative α1-adrenoceptor (α1L subtype) has also been proposed. Recently, three drugs (tamsulosin, naftopidil, and silodosin) have been developed in Japan for the treatment of urinary obstruction in patients with benign prostatic hyperplasia. In this review, we describe recent α1-adrenoceptor subclassifications and the pharmacologic characteristics (subtype selectivity and clinical relevance) of α1-adrenoceptor antagonists.
