Tyramine Induced Hypertension (TIH)-A review

Abstract

Tyramine is a naturally occuring trace amine derived from the amino acid tyrosine and acts as a catecholamine releasing agent. It occurs widely in plants and animals. These include spoiled, picked, aged, smoked or fermented meat, chocolate, alcoholic beverages, fermented foods such as cheese, sour cream, yogurt, shrimp paste, soy sauce, broad (fava) beans, green bean, pods, snow peas endamine, avocados, bananas, pineapples, egg plants, figs, red plums, raspberries, peanuts, brazil nuts, coconuts, processed meat, yeast, etc. Biochemically, tyramine is produced by the decarboxylation of tyrosine via the action of the enzyme tyrosine decarboxylase. In humans, tyramine is produced from tyrosine in the presence of Dopa decarboxylase. Tyramine is taken up into nerve terminals by norepinephrine reuptake transporter (NET) and causes the release of catecholamines. It has been proposed that this results from reverse transport of NET. The effects of tyramine are increased in the presence of MAO inhibitors. Tyramine is physiologically metabolized by monamine oxidases (primarily MAO-A), FMO3, PNMI, DBH and CYP2D6. In humans, if monoamine oxidase inhibitors (MAOI’s) and foods high in tyramine are ingested, tyramine is not degraded and a hypertensive crisis can result from tyramine displacing stored monoamines such as dopamine, norepinephrine, and epinephrine from synaptic vesicles. The first sign of this were discovered by a British pharmacist who noticed his wife, who at the time was on monoamine oxidase inhibitor medication, has several headaches with moderately elevated blood pressure when eating cheese. This is why the crisis is still called “cheese effect” or “cheese crisis”, although other foods can cause the same problem, or much betier ‘Tyramine induced hypertension’. Symptoms and signs include Headache (main symptom), palpitation, high blood pressure (160/90 to 220/115mmHg), and associated complications like hemorrhage, hemplegia, intracranial hemorrhage, cardiac arrhythmias, cardiac failure, pulmonary oedema, and death. Agents normally used to lower blood pressure during a hypertensive crisis include: Nifedipine, a calcium channel blocker; Phentolamine, a reversible non selective alpha adrenergic antagonist and Prazosin, a sympatholytic agent.