A comparison of amitriptyline, vasopressin and amitriptyline with vasopressin in nocturnal enuresis

Forty-five children aged 6-14 years with primary nocturnal enuresis were randomised to determine whether desmopressin is more effective than amitriptyline and whether the combination of amitriptyline/desmopressin is more effective than amitriptyline or desmopressin alone. Amitriptyline dosage was 25 mg for children 6-10 years and 50 mg for children aged 10-14 years. Desmopressin (20 micrograms) was given in the same dosage for all age groups. After a run-in period of 2 weeks, children were treated for 16 weeks and then observed for 12 weeks. In the amitriptyline group mean wet nights per week decreased from 5.8 +/- 0.9 to 3.3 +/- 1.9 (P < 0.0005); in the desmopressin group mean wet nights per week decreased from 6.0 +/- 0.9 to 4.7 +/- 1.7 (P < 0.02); in the amitriptyline/desmopressin group mean wet nights per week decreased from 6.3 +/- 0.9 to 3.3 +/- 2.5 (P < 0.0006). When comparing the groups, amitriptyline/desmopressin and amitriptyline were statistically more effective than desmopressin in week 6 (P < 0.009), week 8 (P < 0.03) and week 10 (P < 0.04). No significant side effects occurred. At this dose amitriptyline was more effective than desmopressin and the combination of desmopressin and amitriptyline did not confer any additional benefit.