Comparison of Silodosin and Naftopidil for Efficacy in the Treatment of Benign Prostatic Enlargement Complicated by Overactive Bladder: A Randomized, Prospective Study (SNIPER Study).
We investigated the efficacy of 2 α1-blockers with different affinities for the α1-adrenoceptor subtypes silodosin and naftopidil in the treatment of benign prostatic enlargement complicated by overactive bladder.



This was a prospective, open label, randomized, multicenter study of 350 outpatients with untreated benign prostatic enlargement associated with urinary urgency at least once per week and an OABSS (Overactive Bladder Symptom Score) of 3 or greater. Patients were randomly assigned to receive silodosin 8 mg per day or naftopidil 75 mg per day. Changes in parameters from baseline to 4 and 12 weeks were assessed based on I-PSS (International Prostate Symptom Score), I-PSS quality of life, OABSS and voiding functions measured by uroflowmetry.



On efficacy analysis a total of 314 patients were included in the 2 groups. No significant difference in adverse effects was observed between the groups. Mean I-PSS and I-PSS quality of life scores, and OABSS significantly improved in both groups. Statistically significantly greater improvement in the silodosin group than in the naftopidil group was observed in total OABSS (p = 0.03), I-PSS quality of life score (p = 0.005) and OABSS urgency score (p <0.001) at 12 weeks. In regard to voiding function the maximum urinary flow rate showed significant improvements in both groups but the change in the maximum flow rate in the silodosin group at 12 weeks was significantly greater than in the naftopidil group (3.6 vs 2.1 ml per second).



Silodosin, a pure α1A-adrenoceptor blocker, showed greater improvement in overactive bladder symptoms along with the urinary flow rate in patients with benign prostatic enlargement complicated by overactive bladder compared to naftopidil, an α1D>A-adrenoceptor blocker.
Department of Urology, Nagoya University Graduate School of Medicine, Nagoya, Japan; Department of Urology, Handa Municipal Hospital, Handa, Japan. Electronic address: yoshi44@med.nagoya-u.ac.jp.
Yoshihisa
Y
Matsukawa
Department of Urology, Nagoya University Graduate School of Medicine, Nagoya, Japan; Department of Urology, Miyoshi Municipal Hospital, Miyoshi, Japan.
Yasuhito
Y
Funahashi
Department of Urology, Nagoya University Graduate School of Medicine, Nagoya, Japan; Department of Urology, Tosei Hospital, Seto, Japan.
Shun
S
Takai
Department of Urology, Nagoya University Graduate School of Medicine, Nagoya, Japan.
Tsuyoshi
T
Majima
Ototokiyama Urology Clinic, Nagoya, Japan.
Tadashi
T
Ogawa
Narita-Clinic, Nagoya, Japan.
Harunori
H
Narita
Department of Urology, Nagoya University Graduate School of Medicine, Nagoya, Japan; Department of Urology, Tsushima Municipal Hospital, Tsushima, Japan.
Masashi
M
Kato
Department of Urology, Nagoya University Graduate School of Medicine, Nagoya, Japan.
Momokazu
M
Gotoh
D058668:Adrenergic alpha-1 Receptor Antagonists / Q000494:pharmacology / Q000627:therapeutic use*; D000368:Aged; D006801:Humans; D007211:Indoles / Q000494:pharmacology / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D009281:Naphthalenes / Q000494:pharmacology / Q000627:therapeutic use*; D010879:Piperazines / Q000494:pharmacology / Q000627:therapeutic use*; D011446:Prospective Studies; D011470:Prostatic Hyperplasia / Q000150:complications / Q000188:drug therapy*; D011788:Quality of Life; D018340:Receptors, Adrenergic, alpha-1 / Q000378:metabolism; D016896:Treatment Outcome; D053201:Urinary Bladder, Overactive / Q000188:drug therapy* / Q000209:etiology; D014554:Urination / Q000187:drug effects; D014563:Urodynamics / Q000187:drug effects
C547713:ADRA1A protein, human; C547719:ADRA1D protein, human; D058668:Adrenergic alpha-1 Receptor Antagonists; D007211:Indoles; D009281:Naphthalenes; D010879:Piperazines; D018340:Receptors, Adrenergic, alpha-1; C095285:silodosin; C064357:naftopidil
adrenergic alpha-1 receptor antagonists; naftopidil; overactive; prostatic hyperplasia; silodosin; urinary bladder