A propylamine formed from the cyclization of the side chain of amphetamine. This monoamine oxidase inhibitor is effective in the treatment of major depression, dysthymic disorder, and atypical depression. It also is useful in panic and phobic disorders. (From AMA Drug Evaluations Annual, 1994, p311)
For the treatment of major depressive episode without melancholia.
Tranylcypromine belongs to a class of antidepressants called monoamine oxidase inhibitors (MAOIs). Tranylcypromine is a non-hydrazine monoamine oxidase inhibitor with a rapid onset of activity. MAO is an enzyme that catalyzes the oxidative deamination of a number of amines, including serotonin, norepinephrine, epinephrine, and dopamine. Two isoforms of MAO, A and B, are found in the body. MAO-A is mainly found within cells located in the periphery and catalyzes the breakdown of serotonin, norepinephrine, epinephrine, dopamine and tyramine. MAO-B acts on phenylethylamine, norepinephrine, epinephrine, dopamine and tyramine, is localized extracellularly and is found predominantly in the brain. While the mechanism of MAOIs is still unclear, it is thought that they act by increasing free serotonin and norepinephrine concentrations and/or by altering the concentrations of other amines in the CNS. It has been postulated that depression is caused by low levels of serotonin and/or norepinephrine and that increasing serotonergic and norepinephrinergic neurotransmission results in relief of depressive symptoms. MAO A inhibition is thought to be more relevant to antidepressant activity than MAO B inhibition. Selective MAO B inhibitors, such as selegiline, have no antidepressant effects.
Mechanism of action
Tranylcypromine irreversibly and nonselectively inhibits monoamine oxidase (MAO). Within neurons, MAO appears to regulate the levels of monoamines released upon synaptic firing. Since depression is associated with low levels of monoamines, the inhibition of MAO serves to ease depressive symptoms, as this results in an increase in the concentrations of these amines within the CNS.