Abrupt discontinuation of tricyclic antidepressant drugs: evidence for noradrenergic hyperactivity.

The effect of abrupt discontinuation of amitriptyline, desipramine, or imipramine) on norepinephrine turnover and specific symptoms in seven depressed patients was examined. Turnover, as determined by plasma and urinary 3 methoxy-4-hydroxy-phenylethylene glycol (MHPG), was increased to a peak during the second week following discontinuation. There were no changes in blood pressure or heart rate. Two of the seven patients experienced clear increases in anxiety. The implications for the role of noradrenergic function is discussed.