phenelzine sulfate /fē′nəlzēn/ , a monoamine oxidase inhibitor. ▪ INDICATIONS: It is prescribed in the treatment of depression, especially atypical endogenous depression and depression associated with adverse life events. ▪ CONTRAINDICATIONS: Liver dysfunction, congestive heart failure, pheochromocytoma, concomitant use of sympathomimetic drugs or foods high in tryptophan or tyramine, or known hypersensitivity to this drug prohibits its use. ▪ ADVERSE EFFECTS: Among the most serious adverse effects are orthostatic hypotension, vertigo, constipation, blurred vision, headache, overactivity, and dryness of the mouth. Monoamine oxidase inhibitors produce many adverse drug interactions.