Imipramine interaction with other drugs

Entacapone and imipramine did not interact adversely in a single-dose study. Similarly, tolcapone and desipramine did not interact adversely. Nevertheless, the manufacturers of entacapone and tolcapone recommend caution if they are used with tricyclic antidepressants or other drugs that inhibit noradrenaline (norepinephrine) uptake, such as maprotiline or venlafaxine. 

The clinical importance of these interactions awaits assessment, but be alert for evidence of increased tricyclic antidepressant effects and possibly toxicity if quinidine is added. One report suggested steady-state increases of 30% with imipramine and more than 500% with desipramine in extensive metabolisers. More study is needed. There seems to be no information about the effect of quinidine on other tricyclics. Information about the effect of quinine on tricyclics is very limited, but the effects are smaller than those of quinidine and therefore less likely to result in clinically significant adverse effects. Note that quinidine, possibly quinine, and the tricyclics (notably in overdose) may prolong the QT interval, see also Drugs that prolong the QT interval + Other drugs that prolong the QT interval , p.257. 

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