Pharmacology Of Tranylcypromine

Indication	For the treatment of major depressive episode without melancholia.
Pharmacodynamics	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.
Absorption	Interindividual variability in absorption. May be biphasic in some individuals. Peak plasma concentrations occur in one hour following oral administration with a secondary peak occurring within 2-3 hours. Biphasic absorption may represent different rates of absorption of the stereoisomers of the drug, though additional studies are required to confirm this.
Volume of distribution	1.1-5.7 L/kg
Protein binding	Not Available
Metabolism	Hepatic.
Route of elimination	Not Available
Half life	1.5-3.2 hours in patients with normal renal and hepatic function
Clearance	Not Available
Toxicity	In overdosage, some patients exhibit insomnia, restlessness and anxiety, progressing in severe cases to agitation, mental confusion and incoherence. Hypotension, dizziness, weakness and drowsiness may occur, progressing in severe cases to extreme dizziness and shock. A few patients have displayed hypertension with severe headache and other symptoms. Rare instances have been reported in which hypertension was accompanied by twitching or myoclonic fibrillation of skeletal muscles with hyperpyrexia, sometimes progressing to generalized rigidity and coma.