Tricyclic antidepressant and cardiovascular drug interactions.

Tricyclic antidepressants have anticholinergic, adrenolytic and quinidine-like activity. These actions result in a variety of cardiac and blood pressure effects. Tricyclic antidepressants can reverse the antihypertensive effect of guanethidine and clonidine. Orthostatic hypotension may be increased with diuretics and hydralazine. Myocardial depression may occur with lidocaine, phenytoin or propranolol. Dangerous additive effects may result from concomitant use of a tricyclic antidepressant and either quinidine or procainamide.