Predictive factors for the effect of the α1-D/A adrenoceptor antagonist naftopidil on subjective and objective criteria in patients with neurogenic lower urinary tract dysfunction

Abstract

Objectives: • To assess the effect of α1-D/A adrenoceptor antagonist naftopidil on patients with neurogenic lower urinary tract dysfunction (NLUTD) and voiding difficulty. • To explore the effectiveness of naftopidil in these patients by using urodynamic variables, including pressure flow study (PFS), and to find good and simple parameters (International Prostate Symptom Score (IPSS), Post-void residual urine (PVR), and uroflowmetry (UFM) parameters) as substitution of PFS for predicting the effect of naftopidil.

Patients and methods: • The main inclusion and exclusion criteria were, IPSS ≥8, voiding symptoms with IPSS ≥5, IPSS-quality of life (QOL) ≥2, PVR ≥50 mL, and without prostatic enlargement ≥ 20 mL. • After initial assessment, patients were stepwisely administered for 12 weeks with the following: placebo for 2 weeks, naftopidil 25 mg/day for 2 weeks, naftopidil 50 mg/day for 2 weeks, and naftopidil 75 mg/day for 6 weeks. At the end of both placebo and 6 weeks' naftopidil 75 mg/day, their IPSS, UFM, PVR, and PFS were assessed. • A total of 82 Japanese patients (men 40, women 42) with lower urinary tract symptoms complicated by NLUTD, with a mean age of 63.9 years, were included from private or institutional clinics. • The lesions were spinal cord 42, and peripheral nervous system 40. The spinal cord lesions were all lumbar spine (injury or lumbar canal stenosis).

Results: • In all patients, pressure at maximum urinary flow rate (P(det) Q(max) ) in PFS significantly decreased (P < 0.05), and maximum urinary flow rate in UFM significantly increased (P < 0.01). Analysis of data for men and for women also showed a significant decrease in PVR, %PVR, and total IPSS score. • The degree of improvement of voided volume, PVR (%), and IPSS in patients with PVR <300 mL was significantly greater than those in patients with PVR ≥300 mL. • The degree of improvement of P(det) Q(max) in PFS, and IPSS in patients with bladder contractility was significantly greater than that in patients without bladder contractility.

Conclusions: • α1-D/A adrenoceptor antagonist naftopidil has a significant effect on both symptoms and urodynamic variables of patients of both genders with NLUTD in Japan. • PVR <300 mL and bladder contractility are predictive factors for the efficacy of naftopidil on patients with NLUTD.