Tranylcypromine

Tranylcypromine (sold under the brand name Parnate®) is a monoamine oxidase inhibitor (MAOI) used as an antidepressant drug.

Pharmacology
Tranylcypromine is a non-hydrazine monoamine oxidase inhibitor, and has a rapid onset of action. Some studies indicate that is slowly reversible, taking 30 days to reverse its binding, which makes it irreversible for all practical purposes. It is not clear whether this is due to regeneration of the MAO enzyme or actual reversal of the binding.

The antidepressant activity of tranylcypromine primarily derives from its inhibition of monoamine oxidase, and the multiple reuptake inhibition of one of its metabolites.

It affects tryptamine, 5-HT, melatonin, epinephrine, norepinephrine, dopamine, histamine, phenylethylamine and other amines, as well as having some anticholinergic effect.

Indications
Tranylcypromine is indicated for the treatment of major depressive episodes, without melancholia. The major usage for Tranylcypromine today is in the treatment of treatment-resistant depression and anergic atypical depression. It also has some off-label uses, such as post-traumatic stress disorder.

Contraindications
Tranylcypromine should not be given to patients suspected of having a cerebrovascular defect, nor to patients with cardiovascular disease. Nor should it be given to patients with pheochromocytoma.

As with other MAOIs, those who are taking tranylcypromine must adhere to rigid dietary specifications in order to prevent complications, and must not take any prescription or over-the-counter medications or herbal agents without first consulting their physician.

Patients who have a history of strong headaches should generally not use tranylcypromine, as they may not be able to correctly identify a hypertensive crisis. Patients with preexisting hypertension or hypotension should only be treated with tranylcypromine under expert care in an inpatient setting.

As tranylcypromine has a strong tendency to cause weight loss, it is not generally recommended for patients with a low BMI in an outpatient setting.

Overdose
Symptoms of tranylcypromine overdose are generally more intense manifestations of the effects and side-effects. Doses of up to 750mg/day have been administered for up to 1 year without adverse effects, and doses up to 200mg/day have been administered for decades, giving tranylcypromine a wide safety margin.

In sensitive individuals or at extreme dosages, hypotension may progress to shock.

Rare cases have been reported of hypertensive crises, hyperpyrexia and cramps progressing to rigidity and coma.

Dietary restrictions
Foods high in amine precursors or exogenous amines may cause reactions. The most common example of this, is the hypertensive crisis caused by tyramine, which is found in e.g. aged cheeses, cured meats and certain red wines. Your doctor will provide you with a list of foods to avoid; the most important entries on this list will be the yeast extracts Bovril and Marmite, both of which contain levels of tyramine that are likely to be fatal in a single serving. Spoiled food is also likely to contain dangerous levels of tyramine.