MAO Inhibitors: Tell me About this Antidepressant
MAO inhibitors are a class of antidepressant drugs that were actually
accidentally discovered as a treatment for depression. Physicians noticed that
iproniazid, a drug being tested on patients for tuberculosis, was found
to have an interesting effect in that it actually seem to make patients happier.
Later, it was also discovered to have the same effect on depressed patients.
This antidepressant drug and several other chemically related medications, were
to slow the body's production of the enzyme monoamine oxidase (MAO), from which
it received the name of MAO inhibitors.
Usually, the brain supplies of
the MAO enzyme break down the neurotransmitter norepinephrine. MAO inhibitors
block this enzyme from carrying out this ”breaking down” process and thereby
stop the destruction of norepinephrine. Ultimately this results in an increase
in norepinephrine activity, which in turn reduces symptoms of depression.
Approximately half of the depressed patients who take this antidepressant drug
are helped by it.
As clinicians continued to work
with this antidepressant drug, they found that they also have the potential for
serious medical problems. Many of the foods consumed in a normal diet such as
cheeses, certain fish, bananas, and some wines contain tyramine. Tyramine
is a chemical that can raise blood pressure dangerously if too much accumulates
in the blood system. Usually, MAO in the liver serves the beneficial role of
quickly breaking tyramine down into another chemical, which helps keep blood
pressure under control. Unfortunately, when these antidepressant drugs are
taken to combat depression they also block the production of MAO in the liver
and intestines. This process allows tyramine to accumulate and puts the person
in great danger of high blood pressure and has caused some patients to even pass
MAO Inhibitors are not antidepressant
drugs of convenience. People who take MAO inhibitors must usually avoid a long list of
foods that may contain tyramine. Recently, new MAOI’s have been discovered that
affect norepinephrine levels without disturbing the breakdown of tyramine,
resulting in much less potential for the dietary dangers usually associated with
the traditional antidepressant drug. Some of these medications, which are
referred to as reversible selective MAO inhibitors are currently
available in Canada and Europe but have not yet been approved for use in United
States.MAO inhibitors include the medications Parnate and Nardil.
Information inspired by
Ronald J. Comer’s Abnormal Psychology
By Paul Susic Ph.D. Licensed Psychologist
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