Tamsulosin-d4 is intended for use as an internal standard for the quantification of tamsulosin by GC- or LC-MS. Tamsulosin is a potent antagonist of α1-adrenergic receptors (α1-ARs; Ki = 0.229 nM in a radioligand binding assay).1 It is 3,800-fold selective for α1-ARs over α2-ARs (Ki = 871 nM). Tamsulosin antagonizes norepinephrine-induced contraction of isolated rabbit aorta (pA2 = 10.11) but has no effect on contraction stimulated by histamine, serotonin , angiotensin II , or prostaglandin F2α . In vivo, tamsulosin reverses the pressor effect of phenylephrine in pithed rats. It reversibly reduces fertility in male rats when administered at a dose of 0.15 mg/kg.2 Tamsulosin (1-100 μg/kg) also reduces prostatic pressure in a dose-dependent manner with minimal hypotensive effects in anesthetized dogs.3 Formulations containing tamsulosin have been used in the treatment of benign prostatic hyperplasia.
1.Honda, K., Takenaka, T., Miyata-Osawa, A., et al.Studies on YM-12617: A selective and potent antagonist of postsynaptic α1-adrenoceptorsNaunyn Schmiedebergs Arch. Pharmacol.328(3)264-272(1985) 2.Ratnasooriya, W.D., and Wadsworth, R.M.Tamsulosin, a selective alpha 1-adrenoceptor antagonist, inhibits fertility of male ratsAndrologia26(2)107-110(1994) 3.Sudoh, K., Tanaka, H., Inagaki, O., et al.Effect of tamsulosin, a novel alpha 1-adrenoceptor antagonist, on urethral pressure profile in anaesthetized dogsJ. Auton. Pharmacol.16(3)147-154(1996)