Effectiveness of tamsulosin hydrochloride and its mechanism in improving nocturia associated with lower urinary tract symptoms/benign prostatic hyperplasia

Abstract

To evaluate the action mechanism of α(1)-receptor blockers in improving nocturia, we have studied effectiveness of tamsulosin hydrochloride (TAM) in the patients with nocturia associated with lower urinary tract symptoms/benign prostatic hyperplasia (LUTS/BPH). LUTS/BPH patients with nocturia (nocturnal frequency ≥2 times per day) were administered TAM (0.2 mg/day) for 8 weeks. A frequency volume chart (FVC), the International Prostate Symptom Score (I-PSS), quality of life (QOL) index, post-void residual, and uroflowmetry were recorded before and after TAM administration for the patients. The parameters affected by TAM were examined. The FVC and I-PSS of the 160 patients analyzed revealed significant clinical improvements in the nocturnal frequency. On the basis of the FVC, the patients were divided into two groups: the responder group comprising 97 patients with significantly improved nocturnal frequency and the non-responder group comprising 63 patients with less improvement in the nocturnal frequency. Significant differences between groups were observed in the following parameters: the hours of undisturbed sleep (HUS), the interval between the time of sleeping and the first instance of nocturnal voiding, the volume of urine in the first nocturnal voiding episode, nocturnal urine volume, nocturnal polyuria index, daytime urine volume, maximum and average flow rates, and post-void residual. TAM improved the QOL of LUTS/BPH patients by significantly reducing the nocturnal frequency and increasing HUS; moreover, it improved nocturia by decreasing the nocturnal urine volume.