This is a highly effective group of antidepressant medications that is rarely prescribed on account of their side effect profile and dietary restrictions. This may change, as in 2006 the FDA approved a patch (transdermal) MAOI version of eldepryl (Emsam).
The MAOIs act by inhibiting enzymes MAOI-A and MAOI-B, which are responsible for the breakdown of epinephrine, norepinephrine, and dopamine.
The major caution with MAOIs is that foods containing a substance called tyramine (a protein subunit) can trigger a potentially fatal rise in blood pressure (hypertensive crisis). There is a long list of foods and medications that need to be avoided when on an MAOI, and it includes aged cheeses, beer and ale, Chianti wine, meat and yeast extracts (Marmite, Bovril, and Vegemite), and certain fruits and vegetables including avocados, pineapples, and eggplants.
Anyone taking an MAOI needs to be closely supervised by her prescriber. It’s prudent to wear a wrist bracelet that indicates you’re on an MAOI, as not only can tyramine-containing foods cause a hypertensive crisis, so too can many prescription, over-the-counter and illegal drugs. MAOIs must be washed out of the body before switching to another antidepressant (at least two weeks), and they should be discontinued two weeks prior to surgery (obviously not possible in an emergency).
As with other antidepressants, MAOIs can trigger a switch from depression to a mixed, manic or hypomanic episode.