Objective: To study the treatment efficacy of capsaicin, in the cases of benign prostatic hyperplasia with overactive bladder symptoms.
Material and Method: A prospective study of 20 benign prostatic hyperplasia patients whose overactive bladder symptoms were not improved by alpha1 blockers. All of them underwent intravesical capsaicin instillation at the Faculty of Medicine Siriraj Hospital, Bangkok, between 2004 and 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), and 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), and 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), and 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), and 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 post void residual urine were not affected. No serious adverse effect occurred in this 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