Antidepressants (Depression Medications) (cont.)

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Side effects and potential drug interactions are major factors that influence selection of antidepressants and compliance with therapy. This article discusses side effects and potential drug interactions of the major antidepressant classes.

What are monoamine oxidase inhibitors (MAOIs)?

MAOIs were the first class of antidepressants to be developed. They fell out of favor because of concerns about interactions with certain foods and numerous drug interactions. MAOIs elevate the levels of norepinephrine, serotonin, and dopamine by inhibiting an enzyme called monoamine oxidase. Monoamine oxidase breaks down norepinephrine, serotonin, and dopamine. When monoamine oxidase is inhibited, norepinephrine, serotonin, and dopamine are not broken down, increasing the concentration of all three neurotransmitters in the brain.

Monoamine oxidase also breaks down tyramine, a chemical present in aged cheese, wines, and other aged foods. Since MAOIs inhibit monoamine oxidase they decrease the breakdown of tyramine from ingested food, increasing the level of tyramine in the body. Excessive tyramine can elevate blood pressure and cause a hypertensive crisis. Patients treated with MAOIs should adhere to recommended dietary modifications that reduce the intake of tyramine. Interestingly, the 6 mg/24 hour dose of selegiline transdermal system (EMSAM, and MAO inhibitor) does not require dietary restrictions because at this dose EMSAM does not substantially inhibit tyramine. Higher selegiline transdermal system (EMSAM) doses require dietary restrictions.

What are examples of MAOIs?

  • phenelzine (Nardil)
  • tranylcypromine (Parnate)
  • isocarboxazid (Marplan)
  • selegiline transdermal system (EMSAM)

What are the side effects of MAOIs?

  • MAOIs are associated with headache and insomnia which may decrease with continued use. Headaches may require treatment with nonsteroidal anti-inflammatory drugs (for example, ibuprofen), and insomnia may require treatment with benzodiazepines (for example, diazepam [Valium]) or other drugs for insomnia.
  • Because MAOIs stimulate the nervous system, they may be beneficial for depressed patients who over sleep or are fatigued.
  • Hypertension may occur during therapy with MAOIs. Therefore, blood pressure should be monitored periodically during MAOI treatment. Hypertensive crisis may occur when MAOIs are combined with tyramine containing foods or drugs that constrict blood vessels.
Medically Reviewed by a Doctor on 2/2/2015


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