BRAND NAMES
- International: Omnic, Secotex
- China: Harnal
- Italy: Omnic, Pradif
- Taiwan: Harnalidge D
- U.S.: Flomax PI
 MECHANISM OF ACTION
Tamsulosin exerts a selective postsynaptic action, inhibiting the binding of norepinephrine to the α1 receptors.
Three α1 receptor subtypes have been identified, α1a, α1b and α1d :
- α1a and α1d subtypes are predominant in the prostate, bladder, and detrusor muscle.
- α1b subtypes are largely located on vascular smooth muscle.
Tamsulosin antagonizes selectively α1a and α1d subtypes leading to smooth muscle relaxation in the lower urinary tract resulting in improved urinary flow rates and alleviation of lower urinary tract symptoms.
Compared to nonsubtype-selective α1-adrenoceptor antagonists (e.g. Alfuzosin, Doxazosin and Terazosin), Tamsulosin has minimal effects on blood pressure and a 0.4 mg daily dosage has the lowest potential to reduce blood pressure and causes less symptomatic orthostatic hypotension.
- Treatment of the signs and symptoms of benign prostatic hyperplasia (hesitation before urine flow starts, intermittency, dribbling, weak urinary stream, incomplete emptying of the bladder, nocturia, daytime frequency, urgency and burning).
- Management of distal ureteric calculi to help in the expulsion of the calculi (off label)
The recommended dose is 0.4 mg once daily, after meal. Tamsulosin should be taken at the same time each day
- Hypersensitivity to Tamsulosin
 WARNINGS AND PRECAUTIONS
- Postural hypotension, dizziness, lightheadedness and syncope can occur, especially at initiation of therapy.
- Patients should be screened for the presence of prostate cancer prior to treatment and at regular intervals afterwards because prostate cancer causes many of the symptoms associated with BPH and the two disorders frequently co-exist.
- CYP3A4 and CYP2D6 inhibitors: Tamsulosin is extensively metabolized, mainly by CYP3A4 and CYP2D6. Tamsulosin should not be used in combination with strong inhibitors of CYP3A4 (e.g., ketoconazole). Tamsulosin should be used with caution in combination with moderate inhibitors of CYP3A4 (e.g., erythromycin), in combination with strong (e.g., paroxetine) or moderate (e.g., terbinafine) inhibitors of CYP2D6.
- Concomitant administration of Tamsulosin with a PDE5 inhibitor (Viagra, Levitra, Cialis, Stendra) can result in additive blood pressure lowering effects and symptomatic hypotension.
 PREGNANCY AND LACTATION
- Pregnancy Category B (US). Tamsulosin is not indicated for use in women.
 SIDE EFFECTS
The most commonly adverse reactions are asthenia, orthostatic hypotension, headache, retrograde ejaculation, and dizziness
Priapism has been reported as an extremely rare side effect.
 RELATED LINKS
|Benign Prostatic Hypertrophy|
|5α reductase inhibitors||Dutasteride (Avodart) • Finasteride (Proscar)|
|Alpha 1 antagonists||Alfuzosin (Uroxatral, Xatral) • Doxazosin (Cardura) • Prazosin • Silodosin (Silodyx, Rapaflo) • Tamsulosin (Omnic, Flomax, Secotex) • Terazosin (Hytrin)|
|Phytotherapy||Pygeum africanum • Serenoa repens|
|PDE5 inhibitors||Tadalafil (Cialis)|
|Combination products||Dutasteride/Tamsulosin (Combodart, Jalyn, Duodart)|