Systematic (IUPAC) name
Clinical data
Trade names Flomax
Licence data US FDA:
  • AU: B2
  • US: B (No risk in non-human studies)
Legal status
Routes of
Pharmacokinetic data
Bioavailability 100% (oral)
Metabolism hepatic
Biological half-life 9–13 hours
Excretion 76% renal
CAS Registry Number  Y
ATC code G04
PubChem CID:
DrugBank  Y
ChemSpider  Y
Chemical data
Formula C20H28N2O5S
Molecular mass 408.51

Tamsulosin (rINN) ( or ) is an α1aadrenergic receptor antagonist used in the symptomatic treatment of benign prostatic hyperplasia (BPH). Tamsulosin was developed by Yamanouchi Pharmaceuticals (now part of Astellas Pharma) and was first marketed in 1996 under the trade name Flomax, and also under the name Omnic.

Tamsulosin is used in the treatment of difficult urination, a common symptom of enlarged prostate. Tamsulosin, and other medications in the class called alpha blockers, work by relaxing bladder neck muscles and muscle fibers in the prostate itself and make it easier to urinate.[1]

The U.S. patent for Flomax expired in October 2009.[2] The U.S. Food and Drug Administration (FDA) approved generic Flomax in March 2010.[3]


  • Mechanism 1
  • Clinical uses 2
  • Adverse effects 3
  • Clinical comparison 4
  • Use in combination therapy 5
  • Brand names 6
  • References 7
  • External links 8


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.[4]

When alpha 1 receptors in the bladder neck and the prostate are blocked, this causes a relaxation in smooth muscle and therefore less resistance to urinary flow. Due to this, the pain associated with BPH can be reduced.

Selective action of tamsulosin in alpha 1A/D receptors is controversial and over three quarters of tamsulosin registered human studies are unpublished.[5]

Clinical uses

Flomax 0.4 MG Oral Capsule

Tamsulosin is primarily used for benign prostatic hyperplasia, but can also assist the passage of kidney stones by the same mechanism of smooth muscle relaxation via alpha antagonism.[6][7] Tamsulosin is also used as adjunct treatment of acute urinary retention. Multiple studies have shown patients will void more successfully after catheter removal if they are taking tamsulosin vs. placebo. Patients taking tamsulosin are also less likely to need re-catheterization.[8][9][10] An additional use for tamsulosin is its use in medical expulsive therapy for some cases of nephrolithiasis.

Adverse effects

Tamsulosin has also affected sexual function in men. It can cause males to experience retrograde ejaculation.[15] 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 bladder sphincter contracts and the ejaculate goes to the urethra, the area of least pressure. In retrograde ejaculation, this sphincter does not function properly. This side effect can be mitigated by exercising the sphincter muscle; this is done by practicing a pumping action during ejaculation and urination - some semen fluid can then be ejaculated.

Clinical comparison

Although prostate specific, it does not have the prostate apoptotic effects of other prostate drugs such as the 5 alpha-reductase inhibitors such as dutasteride and finasteride.

Use in combination therapy

The results of the CombAT (Combination of Avodart and Tamsulosin under the brand name Duodart) trial in 2008 demonstrated that treatment with the combination of dutasteride (Avodart) and tamsulosin provides greater symptom benefits compared to monotherapy with either agent alone for treatment of benign prostatic hyperplasia. [16] The CombAT trial became the medication Jalyn. It was approved by the FDA on June 14, 2010.[17] This combination can be useful as it can take up to six months for any symptomatic relief to be found by 5-alpha-reductase inhibitors such as dutasteride compared to alpha-1 receptor blockers which can provide relief in some cases within 48 hours.[18]

Brand names

Tamsulosin was first marketed in 1996 under the trade name Flomax. It is now marketed by various companies under licence, including Boehringer-Ingelheim and CSL. Tamsulosin hydrochloride extended-release capsules are marketed under the trade names Urisurge(India), Flomax, Flomaxtra, Contiflo XL,bestflo, Urimax and Pradif,[19] although generic, non-modified-release capsules are still approved and marketed in many countries (such as Canada). In Mexico, it is marketed as Secotex and as Harnal D in Japan and Indonesia.[20] In Egypt,[21] Italy and Iceland, it is marketed under the trade name Omnic by Astellas Pharma Europe. The largest manufacturer of tamsulosin, drug substance, is Synthon.


  1. ^ http://www.mayoclinic.com/health/prostate-gland-enlargement/DS00027/DSECTION=treatments-and-drugs
  2. ^ "Flomax – Big Patent Expirations of 2010". February 10, 2010. Retrieved 14 January 2012. 
  3. ^ "FDA Approves First Generic Tamsulosin to Treat Enlarged Prostate Gland" (Press release).  
  4. ^ Shen, Howard (2008). Illustrated Pharmacology Memory Cards: PharMnemonics. Minireview. p. 13.  
  5. ^ http://www.bmj.com/content/347/bmj.f6320/rr/698284. 
  6. ^ http://www.renalandurologynews.com/tamsulosin-aids-stone-expulsion/article/193855/
  7. ^ http://www.prnewswire.com/news-releases/study-shows-use-of-tamsulosin-or-nifedipine-helps-patients-to-clear-ureteral-stone-fragments-faster-and-reduces-rate-of-recurrence-54518887.html
  8. ^ Lucas MG, Stephenson TP, Nargund V (February 2005). "Tamsulosin in the management of patients in acute urinary retention from benign prostatic hyperplasia". BJU Int. 95 (3): 354–7.  
  9. ^ Jeong IG, You D, Yoon JH, et al. (February 2014). "Impact of tamsulosin on urinary retention following early catheter removal after robot-assisted laparoscopic radical prostatectomy: A prospective randomized controlled trial". Int. J. Urol. 21 (2): 164–8.  
  10. ^ PharmacistAnswers Tamsulosin & Catheterization Retrieved February 12, 2014.
  11. ^ "Tamsulosin (Oral Route) - Before Using".  
  12. ^ Medscape, Good Cataract Surgery Outcomes Possible in Intraoperative Floppy Iris Syndrome Due to Tamsulosin.
  13. ^ Bird, ST; Delaney, JA; Brophy, JM; Etminan, M; Skeldon, SC; Hartzema, AG (Nov 5, 2013). "Tamsulosin treatment for benign prostatic hyperplasia and risk of severe hypotension in men aged 40-85 years in the United States: risk window analyses using between and within patient methodology.". BMJ (Clinical research ed.) 347: f6320.  
  14. ^ Ramirez, J (Nov 5, 2013). "Severe hypotension associated with α blocker tamsulosin.". BMJ (Clinical research ed.) 347: f6492.  
  15. ^ "Tamsulosin Side Effects". Drugs.com. Retrieved 2011-04-27 
  16. ^ 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.  
  17. ^ http://www.accessdata.fda.gov/drugsatfda_docs/nda/2010/022460Orig1s000Approv.pdf
  18. ^ Australian Medicines Handbook
  19. ^ Dr. Sandro Magnanelli; Dr.ssa Ada Maria Vetere. "Pradif 0,4 Mg Capsule Rigide A Rilascio Prolungato". Torrinomedica.it. Retrieved 15 November 2012. 
  20. ^ "Drugs.com Database". 
  21. ^ "Novartis hits Astellas with transplant drug generic". Reuters. 11 August 2009. Retrieved 11 August 2009. 

External links

  • Tamsulosin – information from USP DI Advice for the Patient
  • Flomax (drugs.com) – U.S. product information
  • Product label U.S. Food and Drug Administration (FDA)
  • Flomax (Official Site) – Official Site