Comparison of silodosin and naftopidil for efficacy in the treatment of benign prostatic enlargement complicated by overactive bladder: A randomized, prospective study (SNIPER study)

To investigate the efficacy of two α1-blockers with different affinity for α1 adrenoceptor subtypes, silodosin and naftopidil, in the treatment of benign prostatic enlargement (BPE) complicated by overactive bladder (OAB).

This was a prospective, open-label, randomized, multicenter study involving 350 outpatients with untreated BPE associated with urinary urgency at least once per week and OAB Symptom Score (OABSS) of ≥ 3. The patients were randomly assigned to receive silodosin at 8 mg/day or naftopidil at 75 mg/day. Changes in parameters from baseline to 4 and 12 weeks were assessed based on IPSS, IPSS-QOL, OABSS, and voiding functions as measured by uroflowmetry.

In efficacy analysis, 314 patients were included in both groups. No significant difference in adverse effects was observed between the two groups. Mean IPSS, IPSS-QOL score, and OABSS significantly improved in both groups. Statistically significant greater improvement in the silodosin group than in the naftopidil group was observed in total OABSS (p = 0.03), IPSS-QOL score (p = 0.005), and OABSS urgency score (p < 0.001) at 12 weeks. In voiding function, maximum urinary flow rate showed significant improvements in both groups, but the change of maximum flow rate in the silodosin group (+3.6 mL/s) at 12 weeks was significantly greater as compared to that in the naftopidil group (+2.1 mL/s).

Silodosin, a pure α1A-adrenoceptor blocker, showed a greater improvement of OAB symptoms along with urinary flow rate in BPE patients complicated by OAB, compared to naftopidil, an α1D>A-adrenoceptor blocker.

The Journal of urology. 2016 Sep 08 [Epub ahead of print]

Yoshihisa Matsukawa, Yasuhito Funahashi, Shun Takai, Tsuyoshi Majima, Tadashi Ogawa, Harunori Narita, Masashi Kato, Momokazu Gotoh

Department of Urology, Nagoya University Graduate School of Medicine, Nagoya, Japan; Department of Urology, Handa municipal hospital, Handa, Japan. Electronic address: ., Department of Urology, Nagoya University Graduate School of Medicine, Nagoya, Japan; Department of Urology, Miyoshi municipal hospital, Miyoshi, Japan., Department of Urology, Nagoya University Graduate School of Medicine, Nagoya, Japan; Department of Urology, Tosei hospital, Seto, Japan., Department of Urology, Nagoya University Graduate School of Medicine, Nagoya, Japan., Ototokiyama urology clinic, Nagoya, Japan., Narita-clinic, Nagoya, Japan., Department of Urology, Nagoya University Graduate School of Medicine, Nagoya, Japan; Department of Urology, Tsushima municipal hospital, Tsushima, Japan.

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