Tamsulosin Explained

Tamsulosin, sold under the brand name Flomax among others, is a medication used to treat symptomatic benign prostatic hyperplasia (BPH) and chronic prostatitis and to help with the passage of kidney stones.^{[1] [2] [3]} The evidence for benefit with a kidney stone is better when the stone is larger.^[3] Tamsulosin is taken by mouth.^[1]

Common side effects include dizziness, headache, sleeplessness, nausea, blurry vision, and sexual problems.^[1] Other side effects may include feeling lightheaded with standing due to changes in blood pressure, and angioedema. Tamsulosin is an alpha blocker and works by relaxing muscles in the prostate.^[4] Specifically it is an α₁ adrenergic receptor blocker.^[1]

Tamsulosin was approved for medical use in the United States in 1997.^[1] It is available as a generic medication.^[5] In 2021, it was the 24th most commonly prescribed medication in the United States, with more than 23million prescriptions.^{[6] [7]}

Medical uses

Tamsulosin is primarily used for benign prostatic hyperplasia (BPH) and to help with the passage of kidney stones.^{[8] [9]} 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 recatheterization.^[10]

Tamsulosin does not decrease the overall size of the prostate in men with BPH, and is not recommended for prevention of prostate cancer.^[11]

Combination therapy

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.^[12] The CombAT trial became the medication Jalyn. It was approved by the FDA on 14 June 2010.^[13] This combination can be useful because it may take up to six months for symptomatic relief to be found when using 5-alpha-reductase inhibitors such as dutasteride compared to alpha-1 receptor blockers, which can provide relief in some cases within 48 hours.^[14]

Adverse effects

• 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 person's history with this drug, and thus having the option of alternative techniques.^[15]
• Severe hypotension.^{[16] [17]}
• Persons with cardiac conditions including hypotension, mechanical heart failure (valvular, pulmonary embolism, pericarditis), and congestive heart failure should be monitored carefully while taking tamsulosin.
• Alpha blockers, including prazosin, terazosin, doxazosin, or tamsulosin, do not appear to affect all-cause mortality in heart failure rehospitalization in those also receiving β-blockers.^[18]
• 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.^[19]

Mechanism

See main article: Alpha blocker. Tamsulosin is a selective α₁ receptor antagonist that has preferential selectivity for the α_1A receptor in the prostate versus the α_1B receptor in the blood vessels.^[20]

When alpha 1 receptors in the bladder neck, prostate, ureter, and urethra are blocked, a relaxation in smooth muscle tissue results. This mechanism decreases resistance to urinary flow, reduces discomfort associated with BPH, and facilitates passage of kidney stones.

Brand names

Tamsulosin was first marketed in 1996 under the trade name Flomax. The U.S. patent expired in October 2009.^[21] The U.S. Food and Drug Administration (FDA) approved generics in March 2010.^[22] In 2010, tamsulosin was available as OTC medication in UK.^[23]

It is 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),Tamlocept 0.4 (India), Flomax, Flomaxtra, Contiflo XL, bestflo, Mecir LP (France), Urimax, Pamsvax, and Pradif,^[24] although generic, unmodified-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.^[25] 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.^[26] In Egypt,^[27] Italy, Russia and Iceland, it is marketed under the trade name Omnic by Astellas Pharma Europe. The largest manufacturer of tamsulosin is Synthon BV (the Netherlands). Tamsulosin hydrochloride is marketed in Bangladesh under the trade names Uromax, Prostanil MR, Tamisol MR, and Tamsin.

Notes and References

1. Web site: Tamsulosin Hydrochloride Monograph for Professionals . Drugs.com . AHFS . 24 December 2018 . en.
2. Web site: Prostatitis . NHS . 24 December 2018 . en . 19 October 2017.
3. Wang RC, Smith-Bindman R, Whitaker E, Neilson J, Allen IE, Stoller ML, Fahimi J . Effect of Tamsulosin on Stone Passage for Ureteral Stones: A Systematic Review and Meta-analysis . Annals of Emergency Medicine . 69 . 3 . 353–361.e3 . March 2017 . 27616037 . 10.1016/j.annemergmed.2016.06.044 . free .
4. Book: Hutchison LC, Sleeper RB . Fundamentals of Geriatric Pharmacotherapy: An Evidence-Based Approach . 2010 . ASHP . 9781585283057 . 209 . en.
5. Book: British national formulary : BNF 76. 2018. Pharmaceutical Press. 9780857113382. 767. 76.
6. Web site: The Top 300 of 2021 . ClinCalc . 14 January 2024 . 15 January 2024 . https://web.archive.org/web/20240115223848/https://clincalc.com/DrugStats/Top300Drugs.aspx . live .
7. Web site: Tamsulosin –Drug Usage Statistics . ClinCalc . 14 January 2024.
8. Web site: Tamsulosin Aids Stone Expulsion . Renal and Urology News . 7 January 2011 . 4 October 2012 . 14 May 2012 . https://web.archive.org/web/20120514032753/http://www.renalandurologynews.com/tamsulosin-aids-stone-expulsion/article/193855/ . dead .
9. Web site: Study Shows Use of Tamsulosin or Nifedipine Helps Patients to Clear Ureteral Stone Fragments Faster and Reduces Rate of Recurrence .
10. Lucas MG, Stephenson TP, Nargund V . Tamsulosin in the management of patients in acute urinary retention from benign prostatic hyperplasia . BJU International . 95 . 3 . 354–357 . February 2005 . 15679793 . 10.1111/j.1464-410X.2005.05299.x . 30254915 .
11. Book: Medical-surgical nursing : assessment and management of clinical problems. Lewis SM, Dirksen SR, Heitkemper MM, Bucher LH . 2013. 978-0-323-10089-2. 9th. St. Louis, Missouri. 228373703.
12. Roehrborn CG, Siami P, Barkin J, Damião R, Major-Walker K, Morrill B, Montorsi F . 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 . The Journal of Urology . 179 . 2 . 616–621; discussion 621 . February 2008 . 18082216 . 10.1016/j.juro.2007.09.084 .
13. http://www.accessdata.fda.gov/drugsatfda_docs/nda/2010/022460Orig1s000Approv.pdf FDA approval letter
14. Australian Medicines Handbook
15. Medscape, Good Cataract Surgery Outcomes Possible in Intraoperative Floppy Iris Syndrome Due to Tamsulosin.
16. Bird ST, Delaney JA, Brophy JM, Etminan M, Skeldon SC, Hartzema AG . 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 . f6320 . November 2013 . 24192967 . 3817852 . 10.1136/bmj.f6320 .
17. Ramirez J . Severe hypotension associated with α blocker tamsulosin . BMJ . 347 . f6492 . November 2013 . 24192968 . 10.1136/bmj.f6492 . free . 24324483 . 10906/78488 .
18. Page RL, O'Bryant CL, Cheng D, Dow TJ, Ky B, Stein CM, Spencer AP, Trupp RJ, Lindenfeld J . 6 . Drugs That May Cause or Exacerbate Heart Failure: A Scientific Statement From the American Heart Association . Circulation . 134 . 6 . e32–e69 . August 2016 . 27400984 . 10.1161/CIR.0000000000000426 . free .
19. Web site: Tamsulosin Side Effects. Drugs.com. 27 April 2011.
20. Book: Shen H . Illustrated Pharmacology Memory Cards: PharMnemonics . 2008 . Minireview . 978-1-59541-101-3 . 13.
21. Web site: Flomax – Big Patent Expirations of 2010. 10 February 2010. 14 January 2012. 22 April 2012. https://web.archive.org/web/20120422163615/http://www.fiercepharma.com/special-reports/flomax-big-patent-expirations-2010. dead.
22. FDA Approves First Generic Tamsulosin to Treat Enlarged Prostate Gland. 2 March 2010. U.S. Food and Drug Administration (FDA).
23. OTC tamsulosin for benign prostatic hyperplasia . Drug and Therapeutics Bulletin . 48 . 10 . 113–116 . October 2010 . 20926447 . 10.1136/dtb.2010.10.0052 . 32141889 .
24. Web site: Pradif 0,4 Mg Capsule Rigide A Rilascio Prolungato . Torrinomedica.it. 15 November 2012 . Magnanelli S, Vetere AM .
25. Web site: Tamsulosina Mylan 0,4 mg cápsulas duras de liberación modificada EFG. cima.aemps.es. 29 October 2018 .
26. Web site: Drugs.com Database .
27. News: Novartis hits Astellas with transplant drug generic. Reuters. 11 August 2009. 11 August 2009.