Description

Simple

A medication used to treat an enlarged prostate or certain types of kidney stones, and to help with difficulty urinating in women.

Clinical

An alpha-1A and alpha-1B adrenergic receptor antagonist used to treat benign prostatic hyperplasia, ureteral stones, prostatitis, and female voiding dysfunction.

Overview

Tamsulosin is a selective alpha-1A and alpha-1B adrenoceptor antagonist that exerts its greatest effect in the prostate and bladder, where these receptors are most common.[Label] It is indicated for the treatment of signs and symptoms of benign prostatic hypertrophy.[Label] Antagonism of these receptors leads to relaxation of smooth muscle in the prostate and detrusor muscles in the bladder, allowing for better urinary flow.[Label] Other alpha-1 adrenoceptor antagonists developed in the 1980s were less selective and more likely to act on the smooth muscle of blood vessels, resulting in hypotension.[5]

Tamsulosin was first approved by the FDA on April 15, 1997.[6]

Pharmacology

Indication

Tamsulosin is indicated for the treatment of signs and symptoms of benign prostatic hyperplasia.[Label]

Tamsulosin is also used off label for the treatment of ureteral stones, prostatitis, and female voiding dysfunction.[ Read more

Pharmacodynamic

Tamsulosin is an alpha adrenoceptor blocker with specificity for the alpha-1A and alpha-1D subtypes, which are more common in the prostate and submaxillary tissue.[ Read more

Mechanism of action

Tamsulosin is a blocker of alpha-1A and alpha-1D adrenoceptors.[Label, Read more

Absorption

Oral tamsulosin is 90% absorbed in fasted patients.[Label] The area under the curve is 151-199ng/mL\*hr for a 0.4mg oral dose and 440-557ng/mL*hr for a 0.8mg oral dose.[Label] The maximum plasma concentration is 3.1-5.3ng/mL for a 0.4mg oral dose and 2.5-3.6ng/mL for a 0.8mg oral dose.[Label] Taking... Read more

Protein binding

Tamsulosin is 94%-99% protein bound, mostly to alpha-1-acid glycoprotein.[Label]

Volume of distribution

16L after intravenous administration.[Label]

Clearance

2.88L/h.[Label]

Half life

The half life in fasted patients is 14.9±3.9 hours.[Label] The elimination half life is 5-7 hours and the apparent half life is 9 to 13 hours in healthy subjects.[Label] In patients who require tamsulosin, the apparent half life is 14-15 hours.[Label]

Route of elimination

97% of an orally administered does is recovered in studies, which 76% in the urine and 21% in the feces after 168 hours.[Label] 8.7% of the dose is excreted as unmetabolized tamsulosin.[Label, Read more

Toxicity

In the event of overdose, patients may experience hypotension and should lie down in a supine position to maintain blood pressure and heart rate.[Label] If further measures are required intravenous fluids should be considered.[Label] If further progression is required, vasopressors may be used and r... Read more

Adverse Effects

Contraindications

  • Route:
    • Oral
  • Dose Form:
    • Capsule
  • Hypersensitivity:
    • true
  • Sex Group: all
  • Regions: US

Food Interactions

  • Take 30 minutes after a meal (always after the same meal). Taking the drug with food minimizes plasma levels variations.

Interactions

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  • Paracetamol(acetaminophen)
  • Paxil(paroxetine)
  • Pamelor(nortriptyline)
  • Panadol(acetaminophen)
  • Patanol(olopatadine ophthalmic)
  • Pataday(olopatadine ophthalmic)
  • Parnate(tranylcypromine)
  • Pazeo(olopatadine ophthalmic)
1-(2-Phenylethyl)-4-phenyl-4-acetoxypiperidine
The metabolism of Tamsulosin can be decreased when combined with 1-(2-Phenylethyl)-4-phenyl-4-acetoxypiperidine.
2,4-thiazolidinedione
The therapeutic efficacy of 2,4-thiazolidinedione can be increased when used in combination with Tamsulosin.
2,5-Dimethoxy-4-ethylamphetamine
The therapeutic efficacy of Tamsulosin can be decreased when used in combination with 2,5-Dimethoxy-4-ethylamphetamine.
2,5-Dimethoxy-4-ethylthioamphetamine
The therapeutic efficacy of Tamsulosin can be decreased when used in combination with 2,5-Dimethoxy-4-ethylthioamphetamine.
4-Bromo-2,5-dimethoxyamphetamine
The therapeutic efficacy of Tamsulosin can be decreased when used in combination with 4-Bromo-2,5-dimethoxyamphetamine.
4-Bromo-2,5-dimethoxyphenethylamine
The therapeutic efficacy of 4-Bromo-2,5-dimethoxyphenethylamine can be decreased when used in combination with Tamsulosin.
4-Methoxyamphetamine
The therapeutic efficacy of 4-Methoxyamphetamine can be decreased when used in combination with Tamsulosin.
5-methoxy-N,N-dimethyltryptamine
The metabolism of 5-methoxy-N,N-dimethyltryptamine can be decreased when combined with Tamsulosin.
7,8-Dichloro-1,2,3,4-tetrahydroisoquinoline
7,8-Dichloro-1,2,3,4-tetrahydroisoquinoline may increase the orthostatic hypotensive activities of Tamsulosin.
Abacavir
Tamsulosin may decrease the excretion rate of Abacavir which could result in a higher serum level.
Abediterol
The therapeutic efficacy of Abediterol can be decreased when used in combination with Tamsulosin.
Abiraterone
The metabolism of Tamsulosin can be decreased when combined with Abiraterone.
Acarbose
Acarbose may decrease the excretion rate of Tamsulosin which could result in a higher serum level.
Acebutolol
Acebutolol may increase the orthostatic hypotensive activities of Tamsulosin.
Aceclofenac
Aceclofenac may decrease the excretion rate of Tamsulosin which could result in a higher serum level.
Acemetacin
Acemetacin may decrease the excretion rate of Tamsulosin which could result in a higher serum level.
Acepromazine
Tamsulosin may increase the orthostatic hypotensive, hypotensive, and antihypertensive activities of Acepromazine.
Acetaminophen
Acetaminophen may decrease the excretion rate of Tamsulosin which could result in a higher serum level.
Acetohexamide
The therapeutic efficacy of Acetohexamide can be increased when used in combination with Tamsulosin.
Acetylsalicylic acid
Acetylsalicylic acid may decrease the excretion rate of Tamsulosin which could result in a higher serum level.
7 References
  1. 1 . Dunn CJ, Matheson A, Faulds DM: Tamsulosin: a review of its pharmacology and therapeutic efficacy in the management of lower urinary tract symptoms. Drugs Aging. 2002;19(2):135-61.PubMed: 11950378
  2. 2 . Matsushima H, Kamimura H, Soeishi Y, Watanabe T, Higuchi S, Tsunoo M: Pharmacokinetics and plasma protein binding of tamsulosin hydrochloride in rats, dogs, and humans. Drug Metab Dispos. 1998 Mar;26(3):240-5.PubMed: 9492387
  3. 3 . Soeishi Y, Matsushima H, Watanabe T, Higuchi S, Cornelissen K, Ward J: Absorption, metabolism and excretion of tamsulosin hydrochloride in man. Xenobiotica. 1996 Jun;26(6):637-45.PubMed: 8810034
  4. 4 . Rivard R: Tamsulosin: ureteral stones (distal). Hosp Pharm. 2015 Jan;50(1):31-3. doi: 10.1310/hjp5001-031.PubMed: 25684798
  5. 5 . Lepor H, Roehrborn C: Historical Overview of Medical Therapy for Benign Prostatic Hyperplasia Reviews in Urology.PubMed:
  6. 6 . FDA Approved Drug Products: Flomax Link
  7. 7 . Urology Times: Urologists no longer primary initiator of tamsulosin Link