Tyramine pressor test: implications and limitations.

Tyramine, an indirectly acting sympathomimetic amine, can be used as a pharmacological tool to assess the peripheral adrenergic activity and its interactions with drugs in man. Of the various techniques used, the tyramine pressor test appears to be the most reliable method. It is convenient to perform and carries no significant morbidity, provided the subjects are selected carefully and the investigation is closely monitored. Basically, the tyramine pressor test involves measurement of systolic blood pressure in response to bolus intravenous tyramine injections. Tyramine sensitivity, which is taken as an index of peripheral adrenergic function, is defined as the amount of tyramine required to increase the systolic blood pressure by 30 mm of Hg and is determined from the dose response curve. Drugs which influence the adrenergic system are likely to alter the tyramine sensitivity. It provides valuable guidance regarding drug interactions and is useful in the assessment of certain neuropsychiatric conditions. However, since tyramine does not cross the blood brain barrier, information regarding only the peripheral effect is obtained.