Rapid conversion from one monoamine oxidase inhibitor to another

BACKGROUND: Numerous sources state that switching from one monoamine oxidase (MAO) inhibitor to another can be done only after a 14-day washout period. In hospitalized patients and severely depressed outpatients, such a wait may be impracticable. METHOD: We reviewed the case histories of eight consecutive and random patients whom we converted from one MAO inhibitor to another within less than the recommended waiting period. RESULTS: Only one patient experienced troubling adverse effects, and these effects were brief and time-limited. The patient's symptoms were indicative of either withdrawal from tranylcypromine or a mild serotonin syndrome. All other patients tolerated the conversion well with minimal or no adverse effects. Four of the eight patients eventually responded to the new MAO inhibitor. CONCLUSION: These results suggest that some patients can be cautiously but rapidly switched from one MAO inhibitor to another without prolonged drug-free periods. Unquestionably, this strategy should be used only when the clinical picture mandates a rapid conversion. Further, it should be reserved for those patients with established high compliance and should include close monitoring and the use of a low-tyramine diet. Extreme caution must still be undertaken in utilizing this approach until larger studies more accurately determine the frequency of serious adverse effects.