Open AccessTamsulosin: α1-Adrenoceptor Subtype-Selectivity and Comparison With Terazosin
Author(s) -
Ikunobu Muramatsu,
Tadatsugu Taniguchi,
Kenichiro Okada
Publication year - 1998
Publication title -
japanese journal of pharmacology/japanese journal of pharmacology
Language(s) - English
Resource type - Journals
eISSN - 1347-3506
pISSN - 0021-5198
DOI - 10.1254/jjp.78.331
Subject(s) - tamsulosin , terazosin , selectivity , affinities , pharmacology , chemistry , endocrinology , stereochemistry , biology , biochemistry , hyperplasia , catalysis
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.