Tamsulosin - An update of its role in the management of lower urinary tract symptoms

Tamsulosin is a selective alpha (1A)- and alpha (1D)-adrenoceptor antagonist. These alpha (1)-receptors are predominant in the prostate, prostatic capsule, prostatic urethra and bladder. The relaxation of prostate and bladder smooth muscles may result in improvement in maximum urine flow (Q(max)) and reduction of lower urinary tract symptoms (LUTS). Tamsulosin 0.4 and 0.8 mg/day in a modified-release formulation was significantly more effective than placebo in large (n >250) double-blind, randomised, multicentre. 12- to 13- week clinical trials in patients with LUTS. A greater increase in Q(max) from baseline was seen in patients receiving tamsulosin 0.4 or 0.8 mg/day (1.4 to 1.79 ml/sec from a baseline of 9.46 to 10.7 ml/sec) than in placebo recipients (0.4 to 0.93 nil/sec from a baseline of 9.75 to 10.4 ml/sec); the between-group difference was significant in two of three studies. Tamsulosin 0.4 or 0.8 mg/day improved total Boyarsky symptom scores from baseline by a significantly greater extent (by 3.0 to 5.2 points from a baseline of 9.5 to 11.1 points) than placebo (1.9 to 3.2 points from a baseline of 9.3 to 11.0 points). In noncomparative extension studies, the improvement in efficacy parameters with tamsulosin treatment was maintained for up to 4 years. Tamsulosin is effective in patients with mild to severe LUTS, patients with diabetes mellitus or those aged greater than or equal to65 years and does not interfere with the antihypertensive action of nifedipine, enalapril or atenolol. Tamsulosin 0.4 mg/day for 12 weeks and tamisulosin 0.2 mg/day for 4 weeks were as effective as alfuzosin 2.5mg three times daily and terazosin 2 mg/day, respectively, in improving Q(max) and symptom score, in randomised comparative trials. With the exception of a numberically greater incidence of abnormal ejaculation, dizziness and rhinitis, the incidence of adverse events with tamsulosin 0.4 mg/day was similar to that seen with placebo in randomised, double-blind studies. The overall incidence of symptoms indicative of orthostasis was 1.4% with tamsulosin 0,4 or 0.8 mg/day treatment. Tamsulosin had less effect on blood pressure than alfuzosin or terazosin. Conclusion: Tamsulosin, an alpha(1)-adrenoceptor antagonist, has a well established place in the treatment of LUTS and has a tolerability profile similar to that of placebo (apart from a higher incidence of abnormal ejaculation, dizziness and rhinitis"). Comparative data have shown tamsulosin to be as effective as other alpha(1)-adrenoceptor antagonists at increasing Q(max) and improving symptom scores.