Drug Interactions - Interactions of Drugs with Potentially Toxic Substances in Food
Well matured cheeses and a variety of other foods contain a substance, related in structure toadrenaline, called tyramine. Tyramine, which is capable of raising blood pressure, is broken down in theliver by an enzyme known as monoamine oxidase (MAO). Thus, under normal circumstances, thetyramine present in foods is not a problem. One class of drugs used for treatment of certain types ofdepression are inhibitors of MAO. Thus, a patient receiving an MAO inhibitor for treatment ofdepression will have diminished levels of the enzyme MAO. If a patient is being treated with an MAOinhibitor and consumes a food containing tyramine, the tyramine will not be broken down to inactiveproducts and the blood pressure raising effects of tyramine will be greatly intensified. Thus, a patienttaking an MAO inhibitor for treatment of depression must receive information on which foods containtyramine and tyramine-like chemicals and avoid such foods. There is also a list of drugs that can causeproblems when taken in conjunction with MAO inhibitors and which must be avoided, e.g. meperidine(Demerol). It is worth noting that the effects of MAO inhibitors persist for a considerable number ofdays after ceasing to take this class of drugs. The bottom-line, take-home message when taking MAOinhibitors is to exert great caution when eating and when taking other drugs.