Brands, Medical Use, Clinical Data
- Capsule (sustained-release)
Brands / Synonyms
Flomax; Harnal; Jalyn; Omnic; Pradif; Tamsolusin; Tamsulosina [Inn-Spanish]; Tamsulosine [Inn-French]; Tamsulosinum [Inn-Latin]
Used in the treatment of signs and symptoms of benign prostatic hyperplasia.
Tamsulosin, an alpha-adrenoceptor blocker with enhanced specificity for the alpha-adrenoceptors of the prostate, is commonly used to treat benign prostatic hyperplasia (BPH).
Mechanism of Action
Tamsulosin is a selective antagonist at alpha-1A and alpha-1B-adrenoceptors in the prostate, prostatic capsule, prostatic urethra, and bladder neck. At least three discrete alpha1-adrenoceptor subtypes have been identified: alpha-1A, alpha-1B and alpha-1D; their distribution differs between human organs and tissue. Approximately 70% of the alpha1-receptors in human prostate are of the alpha-1A subtype. Blockage of these receptors causes relaxation of smooth muscles in the bladder neck and prostate.
Absorption of tamsulosin HCI from capsules 0.4 mg is essentially complete (>90%) following oral administration under fasting conditions.
LD50 = 650 mg/kg (in rats)
Biotrnasformation / Drug Metabolism
Tamsulosin HCI is extensively metabolized by cytochrome P450 enzymes in the liver, however, the pharmacokinetic profile of the metabolites in humans has not been established.
Tamsulosin capsules are contraindicated in patients known to be hypersensitive to tamsulosin HCI or any component of tamsulosin capsules.
Drug-Drug Interactions: The pharmacokinetic and pharmacodynamic interactions between FLOMAX capsules
and other alpha-adrenergic blocking agents have not been determined. However, interactions may be expected and FLOMAX
capsules should NOT be used in combination with other alpha-adrenergic blocking agents.
The pharmacokinetic interaction between cimetidine and FLOMAX capsules was investigated. The results indicate
significant changes in tamsulosin HCI clearance (26% decrease) and AUC (44% increase). Therefore, FLOMAX capsules
should be used with caution in combination with cimetidine, particularly at doses higher than 0.4 mg.
Results from limited in vitro and in vivo drug-drug interaction studies between tamsulosin HCI and
warfarin are inconclusive. Therefore, caution should be exercised with concomitant administration of warfarin and