Beneficial Effect of Increasing the Dose of Tamsulosin to 0.4 mg in Japanese Patients with Benign Prostatic Hyperplasia

OBJECTIVE Tamsulosin is often administered at a dose of 0.2 mg in Japan, Korea, and elsewhere in Asia, while a dose of 0.4 mg is more common in the West. In order to determine the higher dose might also be appropriate in the North-East Asian setting, we studied whether the effect of increasing the dose to 0.4 mg in Japanese patients who had dysuria associated with benign prostatic hyperplasia. PATIENTS AND METHODS Twenty-two cases with a voiding volume ≥ 100 ml assessed by uroflowmetry out of 31 patients with benign prostatic hyperplasia and an IPSS (International Prostate Symptom Score) ≥ 8 whose symptoms were controlled with 0.2 mg of tamsulosin were entered into this study. We evaluated IPSS and QOL (quality of life) score, urinary flow parameters and residual urine volume before and 4 weeks after increasing the dose of tamsulosin. RESULTS Statistical analyses performed using the Wilcoxon test showed no significant alteration in IPSS total score or QOL score with the increased dose, but Qmax (maximum urinary flow rate) improved from 10.1 ± 5.5 ml/s to 12.1 ± 6.5 ml/s (p = 0.013), and residual urine volume improved from 37.6 ± 26.4 ml to 22.2 ± 24.3 ml (p = 0.012). Two of the 31 patients complained of new symptoms; 1 complained of breast pain and the other complained of dizziness. CONCLUSIONS From the lack of side effects of more than moderate grade in the present study, increasing the dose of tamsulosin might be recommended before switching patients to other drugs.