The Effect of Single Dose Imipramine on Nocturnal Urine Output in Patients with Nocturnal Enuresis

ABSTRACT

PURPOSE: The aim of the present study was to investigate the effect of single dose imipramine on nocturnal urine output in patients with nocturnal enuresis. METHODS:A total of 6 monosymptomatic enuretic patients of more than 5 years of age were enrolled in this study. We measured nocturnal urine output, urine osrnolality, creatinine clearance, osmolal clearance, excretion rate of solutes, fractional excretion of sodium and potassium, and plasma vasopressin with and without a single oral dose of imipramine(lmg/kg of body weight) at 8 p.m. RESULTS: The administration of imipramine was followed by a significant decrease in noctumal urine output(P=0.02). Urine osmolality was not significantly increased(P>0.05), but osmolal clearance was significantly decreased during imipramine medication(P=0.03). Urinary excretion rate of sodium and potassium showed a statistically insignificant trend toward lower values during imipramine administration in nocturnal enuretics. Fractional urinary excretion of sodium and potassium was significantly decreased during imipramine medication(P<0.05). There was no significant difference in plasma vasopressin level and creatinine clearance in nocturnal enuretics after imipramine. CONCLUSION: Imipramine has a vasopressin independent antidiuretic effect in patients with nocturnal enuresis. The antidiuretic effect of imipramine can be attributed prirnarily to increased a-adrenergic stimulation in the proximal tubules with secondary increased urea and water reabsorption more distally in the nephron. (J Korean Pediatr Soc 2000;43:792 - 797)