Tyramine studies and the safety of MAOI drugs.

A major source of concern in using MAOIs is the risk of hypertensive crises, often called the "cheese effect" and thought to represent a drug-induced enhancement of the tyramine pressor effect. Several approaches to reduction of this risk are being explored, including use of inhibitors specific for the B vs. the A type of the enzyme, coadministration of tricyclic with MAOI, and development of reversible inhibitors which might be competitively displaced by tyramine. Such approaches require assessment of sensitivity to tyramine, usually given by the intravenous route. The oral tyramine pressor test, while cumbersome and in need of technical refinement, represents a significantly closer laboratory analogue to the clinical situation.