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Tamsulosin Structural Formulae.png
Tamsulosin ball-and-stick.png
Clinical data
Trade namesomnic, Flomax
License data
  • AU: B2
  • US: B (No risk in non-human studies)
Routes of
by mouth
ATC code
Legal status
Legal status
  • AU: S4 (Prescription only)
  • UK: POM (Prescription only)
  • US: ℞-only
Pharmacokinetic data
Bioavailability100% (by mouth)
Elimination half-life9–13 hours
Excretion76% kidney
CAS Number
PubChem CID
ECHA InfoCard100.109.780 Edit this at Wikidata
Chemical and physical data
Molar mass408.51
3D model (JSmol)

Tamsulosin, sold under the trade names Alna and Flomax, is a medication used to treat symptomatic benign prostatic hyperplasia (BPH) and chronic prostatitis[2], help with the passage of kidney stones,[3] and for urinary retention along with other measures.

Tamsulosin, and other medications in the class called alpha blockers, work by relaxing bladder neck muscles and muscle fibers in the prostate itself and making it easier to urinate.[4] It is an α1a adrenergic receptor antagonist.

Tamsulosin was developed by Yamanouchi Pharmaceuticals (now part of Astellas Pharma) and was first marketed in 1996. The U.S. patent expired in October 2009.[5] The U.S. Food and Drug Administration (FDA) approved generics in March 2010.[6]

Medical uses[edit]

Flomax 0.4 MG Oral Capsule

Tamsulosin is primarily used for benign prostatic hyperplasia and to help with the passage of kidney stones.[7][8] Tamsulosin, however, appears to be effective only for stones over 4 mm and less than 10 mm in size.[3]

Tamsulosin is also used as an add-on treatment for acute urinary retention. People may void more successfully after catheter removal if they are taking tamsulosin. People taking tamsulosin also are less likely to need re-catheterization.[9][10][11]

Adverse effects[edit]

  • Immunologic: Higher risk of allergic reaction in those with sulfa allergies.[12]
  • Eyes: People taking tamsulosin are prone to a complication known as floppy iris syndrome during cataract surgery. Adverse outcomes of the surgery are greatly reduced by the surgeon's prior knowledge of the patient's history with this drug, and thus having the option of alternative techniques.[13]
  • Severe hypotension.[14][15]
  • Persons with cardiac conditions including hypotension, mechanical heart failure (valvular, pulmonary embolism, pericarditis) and congestive heart failure should be monitored carefully while taking tamsulosin.
  • In a retrospective analysis of 388 patients with HF (heart failure) and benign prostatic hypertrophy receiving alpha blockers, including prazosin, terazosin, doxazosin, or tamsulosin, Dhaliwal and colleagues found no significant increase in all-cause mortality and HF re-hospitalization in those also receiving β-blockers. However, in those not receiving β-blockade, α-blockade exposure was associated with an increase in HF hospitalization (HR, 1.94; 95% CI, 1.14–3.32). Of note, the majority of patients were receiving tamsulosin (58%). It has been hypothesized that unopposed α1 blockade could lead to β1-receptor stimulation with increases in renin and aldosterone, leading to edema and weight gain. Chronic α1 antagonism may lead to tachyphylaxis according to the American Heart Association ([1] Drugs That May Cause or Exacerbate Heart Failure, A Scientific Statement From the American Heart Association, Urological Medications). Additionally, several reasons have been proposed for an increased risk of HF in patients receiving alpha blockers such as doxazosin as noted by the American Heart Association; these reasons include misdiagnosis of vasodilator-induced edema, a smaller blood pressure reduction with doxazosin, and the unmasking of HF by the discontinuation of other antihypertensive drugs that were protective against HF.[16]
  • Tamsulosin can also cause retrograde ejaculation, which occurs when semen is redirected to the urinary bladder instead of being ejaculated normally. This is because tamsulosin relaxes the muscles of the urethral sphincters, which are normally closed during ejaculation. This side effect can be mitigated by regular pelvic floor (Kegel) exercise and contracting the pelvic floor during ejaculation.[17]

Combination therapy[edit]

The results of the CombAT (combination of dutasteride (Avodart) and tamsulosin, under the brand name Duodart) trial in 2008 demonstrated that treatment with the combination of dutasteride and tamsulosin provides greater symptom benefits compared to monotherapy with either agent alone for treatment of benign prostatic hyperplasia.[18] The CombAT trial became the medication Jalyn. It was approved by the FDA on 14 June 2010.[19] 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.[20]


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.[21]

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.[22]

Brand names[edit]

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 Urimax 0.4(India), Flomax, Flomaxtra, Contiflo XL, bestflo, Mecir LP (France), Urimax and Pradif,[23] although generic, non-modified-release capsules are still approved and marketed in many countries (such as Canada). Generic extended-release tablets are marketed in most countries of the EEA[24]. In Mexico, it is marketed as Secotex and as Harnal D in Japan and Indonesia and as Harnal OCAS (oral controlled absorption system) in Thailand.[25] In Egypt,[26] Italy, Russia and Iceland, it is marketed under the trade name Omnic by Astellas Pharma Europe. The largest manufacturer of tamsulosin, drug substance, is Synthon BV (The Netherlands). Tamsulosin hydrochloride is marketed in Bangladesh under the trade names Uromax, Tamisol MR, Tamsin.[citation needed]


  1. ^ "Tamsulosin". Merriam-Webster Dictionary.
  2. ^ "NHS Choices: Prostatitis".
  3. ^ a b Wang, RC; Smith-Bindman, R; Whitaker, E; Neilson, J; Allen, IE; Stoller, ML; Fahimi, J (7 September 2016). "Effect of Tamsulosin on Stone Passage for Ureteral Stones: A Systematic Review and Meta-analysis". Annals of Emergency Medicine. doi:10.1016/j.annemergmed.2016.06.044. PMID 27616037.
  4. ^ "Benign prostatic hyperplasia (BPH)". Mayo Clinic.
  5. ^ "Flomax – Big Patent Expirations of 2010". 10 February 2010. Retrieved 14 January 2012.
  6. ^ "FDA Approves First Generic Tamsulosin to Treat Enlarged Prostate Gland" (Press release). U.S. Food and Drug Administration (FDA). 2 March 2010.
  7. ^ "Tamsulosin Aids Stone Expulsion". Renal and Urology News.
  8. ^ "Study Shows Use of Tamsulosin or Nifedipine Helps Patients to Clear Ureteral Stone Fragments Faster and Reduces Rate of Recurrence".
  9. ^ 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. doi:10.1111/j.1464-410X.2005.05299.x. PMID 15679793.
  10. ^ 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. doi:10.1111/iju.12225. PMID 23906190.
  11. ^ PharmacistAnswers Tamsulosin & Catheterization Archived 22 February 2014 at the Wayback Machine. Retrieved 12 February 2014.
  12. ^ "Tamsulosin (Oral Route) - Before Using". Mayo Clinic. Retrieved 5 June 2015.
  13. ^ Medscape, Good Cataract Surgery Outcomes Possible in Intraoperative Floppy Iris Syndrome Due to Tamsulosin.
  14. ^ Bird, ST; Delaney, JA; Brophy, JM; Etminan, M; Skeldon, SC; Hartzema, AG (5 November 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. doi:10.1136/bmj.f6320. PMC 3817852. PMID 24192967.
  15. ^ Ramirez, J (5 November 2013). "Severe hypotension associated with α blocker tamsulosin". BMJ (Clinical research ed.). 347: f6492. doi:10.1136/bmj.f6492. PMID 24192968.
  16. ^ http://circ.ahajournals.org/content/134/6/e32#sec-2
  17. ^ "Tamsulosin Side Effects". Drugs.com. Retrieved 27 April 2011
  18. ^ 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.
  19. ^ Approval letter
  20. ^ Australian Medicines Handbook[full citation needed]
  21. ^ Shen, Howard (2008). Illustrated Pharmacology Memory Cards: PharMnemonics. Minireview. p. 13. ISBN 1-59541-101-1.
  22. ^ Bird, S. T.; Delaney, J. A. C.; Brophy, J. M.; Etminan, M.; Skeldon, S. C.; Hartzema, A. G. (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. 347 (nov05 3): f6320–f6320. doi:10.1136/bmj.f6320. ISSN 1756-1833. PMC 3817852. PMID 24192967.
  23. ^ Dr. Sandro Magnanelli; Dr.ssa Ada Maria Vetere. "Pradif 0,4 Mg Capsule Rigide A Rilascio Prolungato". Torrinomedica.it. Retrieved 15 November 2012.
  24. ^ Mylan. "Tamsulosina Mylan 0,4 mg cápsulas duras de liberación modificada EFG" (PDF). cima.aemps.es. Retrieved 29 October 2018.
  25. ^ "Drugs.com Database".
  26. ^ "Novartis hits Astellas with transplant drug generic". Reuters. 11 August 2009. Retrieved 11 August 2009.

External links[edit]