Health and Prostate

Drug Approvals

(British Approved Name Modified, US Adopted Name, rINN)

International Nonproprietary Names (INNs) in main languages (French, Latin, and Spanish):

Pharmacopoeias. In Europe and Japan.

European Pharmacopoeia, 6th ed. (Tamsulosin Hydrochloride). A white or almost white powder. Slightly soluble in water and anhydrous alcohol freely soluble in formic acid.

Adverse Effects, Treatment, and Precautions

As for Prazosin Hydrochloride. Because tamsulosin is selective for a₁ receptors in the prostate the vasodilator effects may be less frequent. Tamsulosin may cause ejaculation abnormalities. It should be avoided in severe hepatic impairment.

Incidence of adverse effects. A study using prescription event monitoring data for more than 12 000 patients treated with tamsulosin found that dizziness, headache, malaise, and hypotension were the adverse effects most commonly reported.

Surgical procedures. In 2005 the manufacturers of tamsulosin warned that a syndrome of flaccidity of the iris, progressive miosis, and potential prolapse (intraoperative floppy iris syndrome IFIS) had been reported in some patients undergoing cataract surgery who were receiving, or had received, alpha Mockers. One group of workers had reported that in one series of 741 patients undergoing cataract surgery, 15 of the 16 who developed IFIS had received tamsulosin. An earlier retrospective study of 511 similar patients by the same workers had found IFIS in 10 of the 16 patients with a history of tamsulosin treatment but no cases in any of the other patients, including in 11 patients who had received other alpha blockers. The US manufacturer stated that although most cases had occurred in patients who had been taking alpha blockers concurrently or up to 2 weeks before surgery the benefit of stopping such therapy before cataract surgery has not been established as a few cases had included patients who discontinued alpha blockers up to 9 months before surgery. The manufacturers of tamsulosin recommend that patients being considered for cataract surgery should be questioned to ascertain whether they are taking the drug. A literature review found that other alpha blockers, including alfuzosin, doxazosin, and terazosin, have also been associated with IFIS in this patient group however, IFIS has been most strongly associated with the use of tamsulosin. In the UK, the MHRA has required the inclusion of a warning in the labelling of all alpha blockers advising patients to inform their cataract surgeon about past and current use of these drugs.

Interactions

As for Prazosin Hydrochloride.

Pharmacokinetics

Tamsulosin is absorbed from the gastrointestinal tract and is almost completely bioavailable. The extent and rate of absorption are reduced by food. After oral doses of an immediate-release preparation, peak plasma concentrations occur after about 1 hour. Tamsulosin is about 99% bound to plasma proteins. It is metabolised slowly in the liver primarily by the cytochrome P450 isoenzymes CYP2D6 and CYP3A4 it is excreted mainly in the urine as metabolites and some unchanged drug. The plasma elimination half-life has been reported to be between 4 and 5.5 hours. Some of the pharmacokinetic values cited above may be altered when tamsulosin is given as a modified-release preparation, the form in which it is usually used for instance, peak plasma concentrations occur about 6 hours after a dose and the apparent elimination half-life may be 10 to 15 hours.

Renal impairment. Plasma-tamsulosin concentrations were reported to be increased in patients with renal impairment when compared with subjects with normal renal function. However, plasma concentrations of unbound, pharmacologically active drug were similar in both groups and it was suggested that the raised total plasma concentrations were due to an increase in plasma protein binding.

Uses and Administration

Tamsulosin is an alpha1-adrenoceptor blocker with actions similar to those of prazosin it is reported to be more selective for the alpha_1A-adrenoceptor subtype, which accounts for about 70% of the a₁ adrenoceptors in the prostate. It is used in benign prostatic hyperplasia to relieve symptoms of urinary obstruction.

In benign prostatic hyperplasia, tamsulosin hydrochloride is given orally in a modified-release formulation, in a dose of 400 micrograms once daily. Licensed US product information states that the dose may be increased after 2 to 4 weeks, if necessary, to 800 micrograms once daily.

Antidepressant-induced genito-urinary disorders. Tamsulosin was used successfully to treat urinary hesitancy observed in 6 male patients receiving reboxetine. Painful ejaculation associated with reboxetine was also treated successfully in 2 men.

Prostatitis. Alpha₁-adrenoceptor blockers are one of a number of classes of drugs that have been tried for symptomatic relief in men with chronic prostatitis. In a 6-week multicentre, double-blind placebo-controlled study involving 58 men with moderate to severe chronic prostatitis/chronic pelvic pain syndrome, tamsulosin 400 micrograms daily produced greater symptomatic relief than placebo the effect was considered clinically significant for men with severe prostatitis. The benefit appeared to take several weeks to develop, and it was considered possible that longer exposure would produce additional benefit.

Renal calculi. In the conservative management of renal calculi there is increasing interest in the possible use of drug treatment to ease the spontaneous passage of the stone down the ureter. Alpha₁-adrenoceptor blockers can decrease smooth muscle spasm in the ureter, reducing obstruction and improving urine flow. In studies of patients with uncomplicated lower ureteral stones, tamsulosin has been reported to improve the rate of stone expulsion and expulsion time, and to reduce analgesic requirements. Tamsulosin was generally given orally in a dose of 400 micrograms daily for up to 4 weeks. Comparison groups were treated with various other antispasmodics including benzodiazepines, phloroglucinol, and nifedipine in most studies patients were also treated with antibacterial prophylaxis, deflazacort, and NSATDs.

A review found evidence suggesting that adjunctive tamsulosin is safe and effective in enhancing the clearance of renal stones with a larger diameter when used with extracorporeal shock wave lithotripsy. Although evidence regarding ureteral stone clearance is inconclusive, adjunctive tamsulosin has been reported to reduce painful episodes.

Preparations

Proprietary Preparations

Argentina: Aclosan Controlpros Espontal Lostam Omnic Reduprost Secotex Tamsuna Tansiloprost

Australia: Flomax Flomaxtra

Austria: Alna

Belgium: Omic

Brazil: Contiflo Omnic Secotex Tamsulon

Canada: Flomax

Chile: Eupen Gotely Omnic Prostall Secotex Sulix Vi-Uril

Czech Republic: Apo-Tamis Damurgin Fokusin Lannatam Omnic Solesmin Taflosin Tamipro Tamsec Tamurox Tanyz Urostad

Denmark: Omnic

Finland: Expros Omnic Tamictor Tamsumin

France: Josir Omix

Germany: Alna Omnic

Greece: Omnic Pradif

Hong Kong: Harnal

Hungary: Fokusin Omnic Provosal Tamsol Tamsudil Tamsugen Tanyz Totalprost Urostad

India: Urimax

Indonesia: Harnal

Ireland: Omnexel Omnic Omsil Tamsu

Israel: Omnic

Italy: Omnic Pradif

Japan: Harnal

Mexico: Asoflon Secotex

The Netherlands: Mapelor Omnic

Norway: Omnic

New Zealand: Flomax Flomaxtra

Philippines: Harnal

Poland: Bazetham Fokusin Omnic Omsal Prostamnic Tamsudil TamsuLek Tanyz Uprox Urostad

Portugal: Omnic Pradif

Russia: Fokusin Hyperprost Omnic

South Africa: Flomax

Spain: Omnic Urolosin

Switzerland: Omix Pradif

Thailand: Harnal

Turkey: Flomax

United Kingdom: Bazetham Contiflo Flomaxf Flomaxtra Stronazon Tabphyn

USA: Flomax

Venezuela: Secotex Tamsulon

Multi-ingredient

India: Urimax  †