RT Journal Article
SR Electronic
T1 Revisiting the Pharmacodynamic Uroselectivity of <em>α</em><sub>1</sub>-Adrenergic Receptor Antagonists
JF Journal of Pharmacology and Experimental Therapeutics
JO J Pharmacol Exp Ther
FD American Society for Pharmacology and Experimental Therapeutics
SP 106
OP 112
DO 10.1124/jpet.119.260216
VO 371
IS 1
A1 Bruna Maria Castro Salomão Quaresma
A1 Amanda Reis Pimenta
A1 Anne Caroline Santos da Silva
A1 André Sampaio Pupo
A1 Luiz Antonio S. Romeiro
A1 Claudia Lucia Martins Silva
A1 François Noël
YR 2019
UL http://jpet.aspetjournals.org/content/371/1/106.abstract
AB α1-Adrenoceptor (AR) antagonists are widely used for the relief of urinary retention secondary to benign prostatic hyperplasia (BPH). While the five Food and Drug Administration–approved α1-AR antagonists (terazosin, doxazosin, alfuzosin, tamsulosin, and silodosin) share similar efficacy, they differ in tolerability, with reports of ejaculatory dysfunction. The aim of the present work was to revisit their α1-AR subtype selectivity as well as of LDT5 (1-(2-methoxyphenyl)-4-[2-(3,4-dimethoxyphenyl) ethyl]piperazine monohydrochloride), a compound previously described as a multitarget antagonist of α1A-/α1D-AR and 5-HT1A receptors, and to estimate their affinity for D2, D3, and 5-HT1A receptors, which are putatively involved in ejaculatory dysfunction. Competition binding assays were performed with native (D2, 5-HT1A) or transfected (human α1A-, α1B-, α1Dt-AR, and D3) receptors for determination of the drug’s affinities. Tamsulosin and silodosin have the highest affinities for α1A-AR, but only silodosin is clearly a selective α1A-AR antagonist, with Ki ratios of 25.3 and 50.2 for the α1D- and α1B-AR, respectively. Tamsulosin, silodosin, and LDT5 (but not terazosin, doxazosin, and alfuzosin) have high affinity for the 5-HT1A receptor (Ki around 5–10 nM), behaving as antagonists. We conclude that the uroselectivity of tamsulosin is not explained by its too-low selectivity for the α1A- versus α1B-AR, and that its affinity for D2 and D3 receptors is probably too low for explaining the ejaculatory dysfunction reported for this drug. Present data also support the design of “better-than-LDT5” new multitarget lead compounds with pharmacokinetic selectivity based on poor brain penetration and that could prevent hyperplastic cell proliferation and BPH progression.SIGNIFICANCE STATEMENT The present work revisits the uroselectivity of the five Food and Drug Administration–approved α1 adrenoceptor antagonists for the treatment of benign prostatic hyperplasia (BPH). Contrary to what has been claimed by some, our results indicate that the uroselectivity of tamsulosin is probably not fully explained by its too-weak selectivity for the α1A versus α1B adrenoceptors. We also show that tamsulosin affinity for D3 and 5-HT1A receptors is probably too low for explaining the ejaculatory dysfunction reported for this drug. Based on our lead compound LDT5, present data support the search for a multitarget antagonist of α1A–α1D and 5-HT1A receptors with poor brain penetration as an alternative for BPH treatment.