The anticholinergic effect of imipramine has been used successfully in managing enuresis

They resemble the phenothiazide derivatives such as chlorpromazine in structure and function. Like the phe-nothiazine derivatives (e.g., chlorpromazine), tricyclic antidepressants (e.g., imipramine) may reduce the seizure threshold and precipitate seizures in epileptic patients, and may cause cholestatic jaundice, movement disorders, and hematologic side effects. 

Unlike the phenothiazine derivatives, the tricyclic antidepressants may increase motor activity, are antidepressant, have a very slow onset and long duration of action, and have a relatively narrow margin of safety and a strong anticholinergic effect. In fact, dry mouth is the most common side effect, and other anticholinergic effects, such as tachycardia, loss of accommodation, constipation, urinary retention, and paralytic ileus, have been reported (see Tables 5 and 7). 

Tricyclic antidepressants, like some of the phenothiazine derivatives, are sedative in nature. Those compounds containing a tertiary amine (imipramine, amitriptyline, and doxepin) are the most sedative. Those compounds containing a secondary amine (nortriptyline and desipramine) are less so, and protriptyline has no sedative effect (see Tables 5 and 7). 

The tricyclic antidepressants also have cardiovascular actions, hi particular, they cause orthostatic hypotension by obtunding the various reflex mechanisms involved in maintaining blood pressure. 

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The anticholinergic effect of imipramine has been used successfully in managing enuresis (Figure 43.5). 

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