Osmoregulation and desmopressin pharmacokinetics in enuretic children

Objective. The aim was to compare responders and nonresponders to antienure tic treatment with desmopressin with respect to pharmacokinetics and renal effects of the drug. Methods. Twelve children, aged 7.6 to 16.2 years, with nocturnal enuresis w ere examined. Six patients were nonresponders and 6 were responders to desm opressin treatment. The children were given 2 mg of desmopressin intravenou sly and plasma concentrations of the drug were monitored overnight. Urine p arameters were followed for 24 hours after desmopressin administration. Ten patients also underwent a thirst provocation test. Results. Desmopressin pharmacokinetics did not differ between the groups. N either nocturnal urine production nor morning urine osmolality after desmop ressin injection differed between responders and nonresponders, whereas the responders produced significantly larger amounts of significantly less con centrated urine during the day after the injection compared with the nonres ponders (urine production, 2.02 +/- 0.84 and 0.77 +/- 0.20 mL/kg/h; urine o smolality, 558 +/- 271 and 883 +/- 134 mOsm/kg). Nonresponders voided with smaller bladder volumes (2.43 +/- 0.68 mL/kg body weight) than responders ( 4.70 +/- 1.21 mL/kg). The responders produced significantly less concentrat ed urine than the nonresponders during the thirst provocation test (607 +/- 185 and 922 +/- 217 mOsm/kg, respectively). Conclusion. Intravenous desmopressin pharmacokinetics and desmopressin rena l effects did not differ between responders and nonresponders to desmopress in treatment. Nonresponders had a smaller spontaneous bladder capacity and responders produced less concentrated urine.