Melatonin pharmacotherapy for nocturia in men with benign prostatic enlargement

Nocturia is a common condition often attributed in aging men to benign prostatic enlargement. Older adults are prone to nocturnal sleep disturbance, of which disturbed circadian rhythm may be a component since it improves with nighttime administration of melatonin. This study was designed to investigate melatonin as a potential treatment for nocturia associated with bladder outflow obstruction in older men.

A total of 20 men with urodynamically confirmed bladder outflow obstruction and nocturia were entered into a randomized, double blind, placebo controlled crossover study assessing the effect of 2 mg controlled release melatonin at night on nocturia. Symptoms were assessed at baseline and after each 4-week treatment period using a frequency volume chart, the International Prostate Symptom Score and symptom problem index. Maximum urinary flow rate and post-void residual urine volume were also assessed.

Baseline frequency of nocturia was 3.1 episodes per night. There were 7 men (35%) with detrusor overactivity and 10 (50%) had nocturnal polyuria. Melatonin and placebo caused a decrease in nocturia of 0.32 and 0.05 episodes per night (p = 0.07) and a decrease in the nocturia bother score of 0.51 and 0.05, respectively (p = 0.008). Nocturia responder rates (a reduction from baseline of at least -0.5 episodes per night) differed between the active medication and placebo groups (p = 0.04). Daytime urinary frequency, International Prostate Symptom Score, relative nocturnal urine volume, maximum urinary flow rate and post-void residual were unaffected by melatonin treatment.

Melatonin treatment is associated with a significant nocturia response rate, improvement in nocturia related bother and a good adverse effect profile. However, it is uncertain whether the observed changes in this study are clinically significant.