Naftopidil-d5 is intended for use as an internal standard for the quantification of naftopidil by GC- or LC-MS. Naftopidil is an antagonist of α1-adrenergic receptors (α1-ARs; Kis = 3.7, 20, and 1.2 nM for α1A-, α1B-, and α1D-ARs, respectively).1 It is selective for α1-ARs over α2-ARs (Ki = 1,793 nM).2 Naftopidil inhibits norepinephrine-induced contractions in various blood vessels isolated from dog, rabbit, guinea pig, or rat with pA2 values ranging from 6.73 to 8.15.2 It reduces prostatic pressure and mean blood pressure in anesthetized dogs when administered at doses of 100 or 1,000 µg/kg.3 Naftopidil also inhibits the growth of androgen-sensitive LNCaP cells and androgen-insensitive PC3 cancer cells with IC50 values of 22.2 and 33.2 µM, respectively.4 Formulations containing naftopidil have been used in the treatment of benign prostatic hyperplasia.
1.Masumori, N.Naftopidil for the treatment of urinary symptoms in patients with benign prostatic hyperplasiaTher. Clin. Risk Manag.7227-238(2011) 2.Muramatsu, I., Yamanaka, K., and Kigoshi, S.Pharmacological profile of the novel α-adrenoceptor antagonist KT-611 (naftopidil)Jpn. J. Pharmacol.55(3)391-398(1991) 3.Takei, R.-i., Ikegaki, I., Shibata, K., et al.Naftopidil, a novel α1-adrenoceptor antagonist, displays selective inhibition of canine prostatic pressure and high affinity binding to cloned human α1-adrenoceptorsJpn. J. Pharmacol.79(4)447-454(1999) 4.Kanda, H., Ishii, K., Ogura, Y., et al.Naftopidil, a selective α-1 adrenoceptor antagonist, inhibits growth of human prostate cancer cells by G1 cell cycle arrestInt. J. Cancer122(2)444-451(2008)