Response of tricyclic-induced jitteriness to a phenothiazine in two patients.

Some patients with panic attacks are extremely sensitive to tricyclic antidepressants and develop jitteriness, shakiness, and insomnia when given very low doses. Two patients who developed this "jitteriness syndrome" while taking tricyclic antidepressants are described. The side effects in these patients were markedly relieved by the addition of perphenazine.