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Silodosin Structural Formula V.1.svg
Clinical data
SynonymsKAD-3213, KMD-3213
License data
  • US: B (No risk in non-human studies)
  • Not approved for use in women
Routes of
ATC code
Legal status
Legal status
  • In general: ℞ (Prescription only)
Pharmacokinetic data
Protein binding97%
MetabolismHepatic glucuronidation (UGT2B7-mediated); also minor CYP3A4 involvement
Elimination half-life13±8 hours
ExcretionRenal and fecal
CAS Number
PubChem CID
CompTox Dashboard (EPA)
ECHA InfoCard100.248.664 Edit this at Wikidata
Chemical and physical data
Molar mass495.534 g/mol g·mol−1
3D model (JSmol)
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Silodosin (trade names Rapaflo (USA), Silodyx (Europe and South Africa), Rapilif (India), Silodal (India), Sildoo(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.[1] Silodosin is marketed under the trade names Rapaflo in the US and Silodyx in Europe.[2]


Since silodosin has high affinity for the α1A 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.[3]

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.[4]


  1. ^ ", Watson Announces Silodosin NDA Accepted for Filing by FDA for the Treatment of Benign Prostatic Hyperplasia". Retrieved 2008-02-13.
  2. ^ European Medicines Agency: Assessment report for Silodyx
  3. ^ Kobayashi, K; Masumori, N; Kato, R; Hisasue, S; Furuya, R; Tsukamoto, T (2009). "Orgasm is preserved regardless of ejaculatory dysfunction with selective α1A-blocker administration". International Journal of Impotence Research. 21 (5): 306–310. doi:10.1038/ijir.2009.27. PMC 2834370. PMID 19536124.
  4. ^ Kobayashi K, Masumori N, Kato R, Hisasue S, Furuya R, Tsukamoto T (December 2009). "Orgasm is preserved regardless of ejaculatory dysfunction with selective alpha1A-blocker administration". Int J Impot Res. 21 (5): 306–10. doi:10.1038/ijir.2009.27. PMC 2834370. PMID 19536124.

External links