Jpn. J. Pharmacol. 78 (3), 331-335 (1998)

Tamsulosin: alpha1-Adrenoceptor Subtype-Selectivity and Comparison With Terazosin

Ikunobu Muramatsu (1), Takanobu Taniguchi (1) and Kenichiro Okada (2)

Departments of (1) Pharmacology and (2) Urology, School of Medicine, Fukui Medical University, Matsuoka, Fukui 910-1193, Japan

Abstract: Selectivity of tamsulosin and terazosin to functional alpha1-adrenoceptors was examined. Both drugs competitively inhibited the contractile responses to noradrenaline in different tissues where the responses were mediated through the alpha1D-, alpha1B- or alpha1L-subtype. Together with the affinities obtained in the binding study with cloned (alpha1a, alpha1b, alpha1d) and native (alpha1A and alpha1B) subtypes, the selectivity of tamsulosin was alpha1A > alpha1L, alpha1D > alpha1B. Terazosin had lower affinity at various subtypes than tamsulosin, but showed relatively high selectivity to the alpha1D-subtype. In the human prostate, tamsulosin was more than 30-fold higher in affinity than terazosin in functional and binding studies.

Keywords: Tamsulosin, Terazosin, alpha1-Adrenoceptor

Copyrightę The Japanese Pharmacological Society 1998

[Back to TOC]