前立腺肥大症患者に対するシロドシンの初回至適投与量・投与方法の検討

Abstract

We investigated the optimum initial dose and timing of administration of α1A-adrenoceptor antagonist silodosin for treatment of lower urinary tract symptoms associated with benign prostatic hyperplasia (BPH/LUTS). Ninety-eight patients were given a 4 mg dose after breakfast (group A), 4 mg after supper (group B), or 4 mg after breakfast and after supper (group C). At baseline, 4, 8 and 12 weeks after treatment, we assessed International Prostate Symptom Score (IPSS) and quality of life (QOL) index. Twenty-five percent or less improvement of total IPSS and no improvement of QOL index compared with baseline were defined as treatment failure at each evaluation point. Otherwise treatment was considered effective. In group A and group B, patients with treatment failure at 4 or 8 weeks after treatment, the dose of silodosin was increased to 8 mg daily. At the end of the study, 83 patients were evaluable. At 12 weeks after treatment, 20 of the 31 patients in group A and 22 of the 29 patients in group B remained on the 4 mg dose ; silodosin was effective in 65 and 76% of the patients, respectively. When patients with dose escalation were included, silodosin was effective in 81 and 90% of the patients, respectivery. Silodosin was effective in 18 of the 23(78%) patients in group C, although improvement of total IPSS and voiding symptom score of IPSS at 12 weeks after treatment was better in group C than in group A or group B, the difference was not significant. In patients with IPSS less than 20, the degree of improvement of IPSS was similar among the 3 groups. In contrast, in patients with IPSS of 20 or greater the degree of improvement was better in group C than in group B or group C, but the difference was not significant. Storage symptom score of IPSS was significantly improved in all 3 groups without any significant difference among the 3 groups. Three patients (52, 59 and 76 years old) experienced abnormal ejaculation. In conclusion, 4 mg of silodosin daily showed effectiveness against BPH/LUTS, but 8 mg of silodosin daily might be better for patients with severe LUTS.