The mechanism of imipramine in enuresis nocturna.

1. To evaluate the mechanism of action of imipramine in enuresis nocturna, we compared the effects of imipramine with those of scopolamine butylbromide in fourteen children suffering from this condition. A double-blind, cross-over design was used. 2. Imipramine, 10--20 mg, was superior to scopolamine butylbromide (10--20 mg), in eleven of the fourteen subjects (P less than 0.01), and the latter drug was no better than the placebo. 3. As scopolamine butylbromide does not cross the blood-brain barrier, it is concluded that peripheral antimuscarinic effects are not important in the beneficial effects of imipramine in enuresis nocturna. 4. The therapeutic effects of imipramine in depression frequently take 3 to 4 weeks to develop. Such a delay was not seen in our enuretic patients. Thus the mechanism of the drug in the two conditions is probably different.