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Tamsulosin: Wikis


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Systematic (IUPAC) name
CAS number 106133-20-4
ATC code G04CA02
PubChem 129211
DrugBank APRD00036
ChemSpider 114457
Chemical data
Formula C20H28N2O5S 
Mol. mass 408.51
SMILES eMolecules & PubChem
Pharmacokinetic data
Bioavailability 100% (oral)
Metabolism hepatic
Half life 9–13 hours
Excretion 76% renal
Therapeutic considerations
Pregnancy cat. B2 (Aust)
Legal status Schedule 4 (Aust)
Routes oral
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Tamsulosin (rINN) (pronounced /tæmˈsuːloʊsɪn/, /tæmsuˈloʊsɪn/) is an α1a-selective alpha blocker used in the symptomatic treatment of benign prostatic hyperplasia (BPH). Tamsulosin was developed by Yamanouchi Pharmaceuticals (now part of Astellas Pharma) and is marketed by various companies under licence, including Boehringer-Ingelheim and CSL. Tamsulosin hydrochloride extended-release capsules are marketed under the trade names Flomax, Flomaxtra and Urimax, though generic non-modified release capsules are still approved and marketed in many countries, such as Canada. The U.S. patent for Flomax expired October 2009. [1] As of March 12, 2010, at least one major pharmacist (CVS) carries Tamsulosin.



Tamsulosin is a selective α1 receptor antagonist that has preferential selectivity for the α1A receptor in the prostate versus the α1B receptor in the blood vessels.[2]

Clinical uses

Tamsulosin is primarily used for benign prostatic hyperplasia, but is sometimes used for the passage of kidney stones by the same mechanism of smooth muscle relaxation via alpha antagonism.

Adverse effects

Two ADRs (Adverse Drug Reactions) have been reported:

Tamsulosin has also affected the sexual function in men. Tamsulosin can cause males to experience retrograde ejaculation. In males, retrograde ejaculation occurs when the fluid to be ejaculated, which would normally exit the body via the urethra, is redirected to the urinary bladder. Normally, the sphincter of the bladder contracts and the ejaculate goes to the urethra, the area of least pressure. In retrograde ejaculation, this sphincter does not function properly. Occasionally, tamsulosin can cause a drop in blood pressure, rarely resulting in dizziness or fainting. Other reported side effects include headache, dizziness, nasal congestion, and palpitations.

Clinical comparison

Although prostate specific, it does not have the prostate apoptotic effects of other alpha-blockers such as doxazosin and terazosin.

Use in combination therapy

The results of the CombAT (Combination of Avodart and Tamsulosin) trial have recently demonstrated that treatment with the combination of dutasteride and tamsulosin provides superior symptom benefits compared with either monotherapy.[4]


  1. ^ "Novartis hits Astellas with transplant drug generic". Reuters. 11 August 2009. Retrieved 11 August 2009. 
  2. ^ Shen, Howard (2008). Illustrated Pharmacology Memory Cards: PharMnemonics. Minireview. p. 13. ISBN 1-59541-101-1. 
  3. ^ Medscape, Good Cataract Surgery Outcomes Possible in Intraoperative Floppy Iris Syndrome Due to Tamsulosin
  4. ^ Roehrborn CG, Siami P, Barkin J, et al. (February 2008). "The effects of dutasteride, tamsulosin and combination therapy on lower urinary tract symptoms in men with benign prostatic hyperplasia and prostatic enlargement: 2-year results from the CombAT study". J. Urol. 179 (2): 616–21; discussion 621. doi:10.1016/j.juro.2007.09.084. PMID 18082216. 

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