Monoamine Oxidase Inhibitors, Tyramine, and Cheese

Abstract

Marked potentiation of the pressor effects of tyramine hydrochloride, given orally and intravenously, was demonstrated in patients receiving a monoamine oxidase (MAO) inhibitor. Assays of the tyramine content of various foods revealed up to 25μg/ml in wine and 1.4 mg/gm in some cheeses. As little as 20 gm of cheese produced pressor responses which were controllable with phentolamine methane-sulfonate in MAO-inhibited patients. These findings extend previous work on the mechanism of cheese toxicity and emphasize one of the hazards of treatment with MAO inhibitors.