Tamsulosin: alpha1-adrenoceptor subtype-selectivity and comparison with terazosin.
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.
Muramatsu
I
I
Department of Pharmacology, School of Medicine, Fukui Medical University, Matsuoka, Japan.
Taniguchi
T
T
Okada
K
K
D000317:Adrenergic alpha-Antagonists / Q000378:metabolism / Q000494:pharmacology*; D000818:Animals; D001013:Aorta, Thoracic / Q000187:drug effects / Q000378:metabolism / Q000502:physiology; D001667:Binding, Competitive; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D006801:Humans; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009638:Norepinephrine / Q000494:pharmacology; D011224:Prazosin / Q000031:analogs & derivatives / Q000494:pharmacology; D011467:Prostate / Q000187:drug effects / Q000378:metabolism / Q000502:physiology; D011817:Rabbits; D051381:Rats; D018340:Receptors, Adrenergic, alpha-1 / Q000378:metabolism; D013449:Sulfonamides / Q000378:metabolism / Q000494:pharmacology*; D000077409:Tamsulosin
C547713:ADRA1A protein, human; C547716:ADRA1B protein, human; C547719:ADRA1D protein, human; D000317:Adrenergic alpha-Antagonists; D018340:Receptors, Adrenergic, alpha-1; D013449:Sulfonamides; C041226:Terazosin; D000077409:Tamsulosin; D009638:Norepinephrine; D011224:Prazosin