Which medications in the drug class Monoamine Oxidase Inhibitor (MAOI) are used in the treatment of Anxiety Disorders?

Updated: Mar 27, 2019
  • Author: Nita V Bhatt, MD, MPH; Chief Editor: David Bienenfeld, MD  more...
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Monoamine Oxidase Inhibitor (MAOI)

MAOIs are most commonly prescribed for patients with social phobia. They include the agents phenelzine (Nardil), selegiline (Emsam), tranylcypromine (Parnate), and isocarboxazid (Marplan).

Advantages of MAOIs are low risk of dependence and less anticholinergic effect than TCAs. Disadvantages are the higher number of adverse effects, including sexual difficulty, hypotension, and weight gain, and potential lethality in overdose. A diet low in tyramine must be followed to avoid a hypertensive crisis. Over-the-counter medications should be used with great caution.

The use of MAOIs should be limited to cases in which SSRIs are ineffective or cannot be afforded. MAOIs may be especially indicated in treatment-refractory panic disorder and social anxiety disorder. MAOIs also may have a role in the treatment of certain subtypes of OCD refractory to conventional treatment, such as patients with symmetry obsessions or associated panic attacks.

Phenelzine (Nardil)

In one double-blind placebo-controlled trial, was more efficient in reducing intrusion symptoms. Has demonstrated clear superiority over placebo in double-blind trials for treating specific symptoms of panic disorders. Usually reserved for patients who do not tolerate or respond to traditional cyclic or second-generation antidepressants.

Selegiline (Emsam)

Irreversible MAOI. Has greater affinity for MAO-B compared with MAO-A; however, at antidepressant doses, inhibits both isoenzymes. MAO-A and MAO-B catabolize neurotransmitter amines in CNS (eg, norepinephrine, dopamine, serotonin). Indicated for treating major depressive disorder. At lowest strength (ie, 6 mg delivered over 24 h), may be used without the dietary restrictions required for oral MAOIs used to treat depression.

Tranylcypromine (Parnate)

Treats major depression. Binds irreversibly to MAO, thereby reducing monoamine breakdown and enhancing synaptic availability.

Isocarboxazid (Marplan)

Nonselective hydrazine MAOI demonstrated to inhibit MAO in the brain, heart, and liver. Mechanism by which MAOIs act as antidepressants is not fully understood but is thought to involve elevation of brain levels of biogenic amines. However, MAO is a complex enzyme system widely distributed throughout body, and drugs that inhibit MAO cause a number of clinical effects. Thus, it is unknown whether MAO inhibition, other pharmacologic actions, or interaction of both is responsible for the antidepressant effects observed.

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