Tamsulosin Hydrochloride is indicated for the treatment of the signs and symptoms of Benign Prostatic Hyperplasia (BPH).
Antagonist of ?1A-adrenoreceptors
Tamsulosin, a selective alpha1 adrenoceptor blocking agent, exhibits its selectivity for alpha1 A adrenoceptors in human prostate. Blockade of these adrenoceptors can cause smooth muscle in the bladder neck and prostate to relax, resulting in an improvement in urine flow rate and a reduction in symptoms of BPH. Absorption of Tamsulosin hydrochloride capsule 0.4mg is essentially complete (90%) following oral administration under fasting conditions. The time to maximum concentration (Tmax) is reached by four to five hours under fasting conditions and by six to seven hours when administered with food. Tamsulosin hydrochloride is extremely bound to human plasma protein (94% to 99%). Tamsulosin hydrochloride is extensively metabolized by cytochrome P 450 enzymes in the liver and less than 10% of the dose is excreted in urine as unchanged form. Following intravenous or oral administration of an immediate-release formulation the elimination half-life of Tamsulosin hydrochloride in plasma ranges from five to seven hours. Because of the absorption rate controlled pharmacokinetics with Prostam capsules, the apparent half-life of Tamsulosin hydrochloride is approximately 9 to 13 hours in healthy volunteers and 14 to 15 hours in the target population.
The recommended dose of Tamsulosin is 0.4 mg once daily. It should be administered approximately half/hour following the same meal each day. For those patients who fail to respond to the 0.4 mg dose after two to four weeks of dosing, the dose of Tamsulosin can be increased to 0.8mg once daily. If Tamsulosin administration is discontinued or interrupted for several days at either the 0.4 mg or 0.8 mg dose, therapy should be started again with the 0.4 mg once daily dose.
Concurrent administration of other alfa1-adrenoceptor antagonists could lead to hypotensive effects. No interactions have been seen when Tamsulosin was given concomitantly with either atenolol, enalapril or nifedipine. Concomitant cimetidine brings about a rise and frusemide a fall in plasma levels of Tamsulosin, but as levels remain within the normal range posology need not be changed. No interactions at the level of hepatic metabolism have been seen during in vitro studies with liver microsomal fractions (representative of the cytochrome P450-linked drug-metabolizing enzyme system), involving amitriptyline, salbutamol, glibenclamide, and finasteride. Diclofenac and warfarin, however, may increase the elimination rate of Tamsulosin.
History of orthostatic hypotension. Severe hepatic impairment. Not indicated for use in women. Severe renal impairment (CrCl <10 mL/min). Pregnancy and lactation.
The following adverse reactions have been reported during the use of Tamsulosin: dizziness, abnormal ejaculation, and less frequently (1-2%) headache, asthenia, postural hypotension, palpitations, and rhinitis. Gastrointestinal reactions such as nausea, vomiting, diarrhoea, and constipation can occasionally occur. Hypersensitivity reactions such as rash, pruritus, and urticaria can occur occasionally. As with other alpha-blockers, drowsiness, blurred vision, dry mouth, or edema can occur. Syncope has been reported rarely, and there have been very rare reports of angioedema and priapism.
Tamsulosin Hydrochloride capsules are not indicated for use in women.
No case of acute overdosage has been reported. However, acute hypotension is likely to occur after overdosage in which case cardiovascular support should be given. Blood pressure can be restored and the heart rate brought back to normal by lying the patient down. If this does not help then volume expanders, and when necessary, vasopressors could be employed. Renal function should be monitored and general supportive measures applied. Dialysis is unlikely to be of help as Tamsulosin is very highly bound to plasma proteins. Measures, such as emesis, can be taken to impede absorption. When large quantities are involved, gastric lavage can be applied and activated charcoal and an osmotic laxative, such as sodium sulphate, can be administered.
Store in a cool and dry place, below 30°C, protected from light.
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