Silodosin

Silodosin

Clinical data
Pregnancy category	US: B (No risk in non-human studies) Not approved for use in women
Routes of administration	Oral
ATC code	G04CA04 (WHO)
Legal status
Legal status	In general: ℞ (Prescription only)
Pharmacokinetic data
Bioavailability	32%
Protein binding	97%
Metabolism	Hepatic glucuronidation (UGT2B7-mediated); also minor CYP3A4 involvement
Biological half-life	13±8 hours
Excretion	Renal and fecal
Identifiers
IUPAC name 1-(3-hydroxypropyl)-5-[(2R)-({2-[2-[2-(2,2,2-trifluoroethoxy)phenoxy]ethyl}amino)propyl]indoline-7-carboxamide
Synonyms	KAD-3213, KMD-3213
CAS Number	160970-54-7 N
PubChem CID	5312125
IUPHAR/BPS	493
ChemSpider	4471557 Y
UNII	CUZ39LUY82
ChEMBL	CHEMBL24778 Y
Chemical and physical data
Formula	C25H32F3N3O4
Molar mass	495.534 g/mol
3D model (Jmol)	Interactive image
SMILES FC(F)(F)COc3ccccc3OCCN[C@H](C)Cc1cc2c(c(c1)C(=O)N)N(CC2)CCCO
InChI InChI=1S/C25H32F3N3O4/c1-17(30-8-12-34-21-5-2-3-6-22(21)35-16-25(26,27)28)13-18-14-19-7-10-31(9-4-11-32)23(19)20(15-18)24(29)33/h2-3,5-6,14-15,17,30,32H,4,7-13,16H2,1H3,(H2,29,33)/t17-/m1/s1 Y Key:PNCPYILNMDWPEY-QGZVFWFLSA-N Y
NY (what is this?)

Silodosin (trade names Rapaflo (USA), Silodyx (Europe and South Africa), Rapilif (India), Silodal (India), Urief (Japan), Thrupas (South Korea), Urorec (Russia)) is a medication for the symptomatic treatment of benign prostatic hyperplasia. It acts as an α₁-adrenoceptor antagonist with high uroselectivity (selectivity for the prostate).

Silodosin received its first marketing approval in Japan in May 2006 under the tradename Urief, which is jointly marketed by Kissei Pharmaceutical Co., Ltd. and Daiichi Sankyo Pharmaceutical Co., Ltd.

Kissei licensed the US, Canadian, and Mexican rights for silodosin to Watson Pharmaceuticals, Inc. in 2004.

FDA approved silodosin on October 9, 2008. Silodosin is marketed under the trade names Rapaflo in the US and Silodyx in Europe.

Since silodosin has high affinity for the α_1A adrenergic receptor, it causes practically no orthostatic hypotension (in contrast to other α₁ blockers). On the other side, the high selectivity seems to be the cause of silodosin's typical side effect of loss of seminal emission.

As α_1A 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.