Objective: To study the efficacy of capsaicin in treating overactive bladder symptoms in benign prostatic hyperplasia patients.
Material and Method: A prospective study of 20 benign prostatic hyperplasia patients whose overactive bladder symptoms were not improved by alpha1 blocker. Alpha1 blocker was taken about 22.9 + 17.2 months before and continued throughout 6 months duration of the present study. All of them had undergone intravesical capsaicin instillation at the Faculty of Medicine Siriraj Hospital, Bangkok, from 2004 to 2006. Both clinical and urodynamic data were evaluated before and after treatment.
Results: Mean urgency decreased from 6.7 + 5.1 at baseline to 2.0 + 2.3 (p < 0.005), 1.4 + 2.4 (p < 0.005), 1.3 + 2.2 (p < 0.005) at 1, 3 and 6 months. Mean urge incontinence decreased from 1.7 + 3.5 at baseline to 0.5 + 1.3 (p = 0.148), 0.4 + 1.2 (p = 0.114), 0.3 + 1.1 (p = 0.085) at 1, 3 and 6 months. Mean urinary frequency decreased from 13.7 + 3.3 at baseline to 10.5 + 2.8 (p < 0.005), 9.6 + 2.0 (p < 0.005), 9.5 + 2.6 (p < 0.005) at 1, 3 and 6 months. Mean nocturia decreased from 4.7 + 2.4 at baseline to 3.1 + 2.2 (p < 0.005), 2.7 + 1.2 (p < 0.005), 2.9 + 1.6 (p < 0.005) at 1, 3 and 6 months. Mean first desire to void increased from 172.5 + 100.4 ml at baseline to 210.6 + 99.5 ml (p = 0.016) at 1 month. Mean maximal cystometric capacity increased from 350.3 + 165.9 ml at baseline to 397.4 + 165.7 ml (p = 0.012) at 1 month. Peak flow rate, detrusor pressure, and postvoid residual urine were not affected. No serious adverse effect occurred in the present study.
Conclusion: Intravesical capsaicin instillation is an effective treatment for overactive bladder symptoms in benign prostatic hyperplasia patients.

Keywords: Capsaicin, Benign prostatic hyperplasia, Overactive bladder