Nocturnal enuresis (NE) is a major health problem affecting 15% of children aged older than 5 years. Even though an annual spontaneous resolution rate of 15% has been reported, 1% to 2% of teenagers aged older than 15 years and 2% to 6% of adults continue to deal with this issue.

In a study recently published in The Journal of Urology, researchers examined the efficacy and safety of the selective serotonin reuptake inhibitor, fluoxetine, for treating refractory primary monosymptomatic nocturnal enuresis in children.

The study included pediatric patients aged 8 to 18 years with severe primary monosymptomatic nocturnal enuresis (PMNE) unresponsive to alarm therapy, desmopressin, and anticholinergics. After excluding children with daytime urinary symptoms, constipation, underlying urological, neuropsychiatric, endocrinologic, or cardiac conditions, patients were randomly and equally allocated to receive 10-mg fluoxetine once daily or placebo for 12 weeks.

The primary outcome was treatment response according to the International Children's Continence Society terminology. The secondary outcomes were treatment-related adverse effects and nighttime arousal.

A total of 150 pediatric patients were enrolled, of whom 110 (56 in fluoxetine group and 54 in placebo group) with an average age of 11.8 (SD 2.46) years were evaluated. After 4 weeks, 7.1% and 66.1% of the fluoxetine group achieved complete response and partial response (defined as 50%-99% reduction of the number of wet nights, respectively), versus 0% and 16.7% of the placebo group (P <.001). At 12 weeks, complete and partial responses were achieved in 10.7% and 21.4% of the fluoxetine group, respectively (vs. 0% and 14.8% of the placebo group, P = .023). Fluoxetine-treated patients had fewer wet nights (4.7 [standard deviation (SD), 4.2] fortnightly vs. 9.7 [SD, 3.5] at 4 weeks, P <.001; 5.7 [SD, 4.4] vs. 9.9 [SD, 3.4] at 8 weeks, P <.001; 7.5 [SD, 4.6] vs. 9.9 [SD, 3.4] at 12 weeks, P = .003). Fluoxetine was associated with enhanced nighttime arousal (P = .017). Five (8.9%) patients in the fluoxetine arm had one or more adverse events (AEs) requiring treatment discontinuation. The AEs consisted of two cases of headache/dizziness, and one each of hypersensitivity/skin rash, hair loss, fatigue, depressed mood, and anxiety and were rapidly reversible.

The authors indicated that to the best of their knowledge, this was the first randomized, placebo-controlled trial assessing fluoxetine as a treatment for refractory PMNE in children, but there were some limitations. First, the follow-up is relatively short to demonstrate the long-term efficacy of fluoxetine and the possible relapse rate after treatment discontinuation. Moreover, it is important to note that no withdrawal symptoms were observed in the group of patients who continued follow-up after the study conclusion.

The authors concluded that the use of fluoxetine is a safe therapeutic option for children and adolescents with refractory PMNE that achieves an initial good response. However, the response rate decreases progressively over time.
 
The authors wrote, “We hope that this pilot study will provoke more research to confirm the safety and efficacy of fluoxetine for the treatment of PMNE, compare it to other standard treatments for NE, and explore its use in different patient populations and other forms of childhood incontinence.”

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