Tamsulosin: alpha1-adrenoceptor subtype-selectivity and comparison with terazosin

Jpn J Pharmacol. 1998 Nov;78(3):331-5. doi: 10.1254/jjp.78.331.

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.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adrenergic alpha-Antagonists / metabolism
  • Adrenergic alpha-Antagonists / pharmacology*
  • Animals
  • Aorta, Thoracic / drug effects
  • Aorta, Thoracic / metabolism
  • Aorta, Thoracic / physiology
  • Binding, Competitive
  • Dogs
  • Dose-Response Relationship, Drug
  • Humans
  • Male
  • Muscle Contraction / drug effects
  • Norepinephrine / pharmacology
  • Prazosin / analogs & derivatives
  • Prazosin / pharmacology
  • Prostate / drug effects
  • Prostate / metabolism
  • Prostate / physiology
  • Rabbits
  • Rats
  • Receptors, Adrenergic, alpha-1 / metabolism
  • Sulfonamides / metabolism
  • Sulfonamides / pharmacology*
  • Tamsulosin

Substances

  • ADRA1A protein, human
  • ADRA1B protein, human
  • ADRA1D protein, human
  • Adrenergic alpha-Antagonists
  • Receptors, Adrenergic, alpha-1
  • Sulfonamides
  • Terazosin
  • Tamsulosin
  • Norepinephrine
  • Prazosin