to blood plasma proteins. Its main metabolite is silodosin glucuronide, which inhibits the α1A receptor with 1/8 of the affinity of the parent substance. 91% of the glucuronide are bound to plasma proteins. The enzyme mainly responsible for the formation of the glucuronide is UGT2B7. Other enzymes involved in the metabolism are alcohol dehydrogenases, aldehyde dehydrogenases and CYP3A4. Silodosin is almost completely excreted in the form of metabolites; 33.5% via the urine and 54.9% via the feces. The biological half-life of silodosin is 11 hours on average, and that of the glucuronide is 18 hours or 24 hours. (Sources are contradictory on this.) History Silodosin received its first marketing approval in Japan in May 2006, under the brand name Urief, which is jointly marketed by Kissei Pharmaceutical and Daiichi Sankyo. Kissei licensed the US, Canadian, and Mexican rights for silodosin to Watson Pharmaceuticals (now Allergan) in 2004. AbbVie absorbed Allergan in 2019. The United States Food and Drug Administration and Health Canada approved silodosin under the brand name Rapaflo on 9 October 2008 and 11 January 2011, respectively. Society and culture Brand names Other brand names include Urorec (European Union, Australia, Russia), Niksol (Croatia), Silorel (Jamaica), SiloSoft Sildoo, Silodal Silofast (India), Thrupas (South Korea), and Flopadex (Egypt). Research As α1A adrenoceptor antagonists are being investigated as a means to male birth control due to their ability to inhibit ejaculation but not orgasm, a trial with 15 male volunteers was conducted. While silodosin was completely efficacious in preventing the release of semen in all subjects, 12 out of the 15 patients reported mild discomfort upon orgasm. The men also reported the psychosexual side effect of being strongly dissatisfied by their lack of ejaculation. References External links AbbVie brands Alpha-1 blockers Benzamides Indolines Organofluorides Phenethylamines Phenol ethers Primary alcohols Trifluoromethyl compounds