Monoamine Oxidase Inhibitors MAOIs

Monoamine oxidase inhibitors, or MAOIs, were the first antidepressants to be developed and made available to the general pubic.

­Although they've fallen out of favor due to concerns over certain possible drug and food interactions. Like most antidepressants, doctors aren't entirely sure exactly of their exact mechanism of action, but it is known that they elevate norepinephrine, serotonin and dopamine levels by inhibiting the enzyme monoamine oxidase, which breaks down these three neurotransmitters. This naturally results in higher amounts of these neurotransmitters in the brain.

MAOIs have proven to be every bit as effective as the many other antidepressants that have come after them, but many doctors have been hesitant to prescribe them to some patients due to the side effects and certain interactions with some foods and drugs. One of the more worrisome side effects of using MAOIs is that it can lead to higher levels of tyramine, a chemical commonly found in cheeses, wines, and other aged foods. Monoamine oxidase breaks down tyramine, and excessive tyramine can lead to high blood pressure and can result in a hypertensive crisis. Patients who are prescribed MAOIs for depression are often given very specific dietary restrictions that are intended to control tyramine levels. One of the few MAOIs that do not require dietary restrictions is selegiline transdermal system, or EMSAM. This drug does not substantially inhibit tyramine even at higher doses.

MAOIs are also associated with several potentially dangerous drug interactions, thereby limiting their usefulness for those who are already on several other medications. They often interact with medications that increase serotonin levels in the brain. Changes in serotonin levels can alter moods, so increases in serotonin levels are usually a desired result of the use of many antidepressants.

Some of these drugs include:

  • Serotonin reuptake inhibitors such as sertraline and fluoxetine, otherwise known as Zoloft and Prozac respectively
  • Tricyclic antidepressants such as Tofranil
  • St. John's Wort
  • Meperidine
  • Ultram
  • Methadone

Combining MAOIs with these or similar drugs can have many negative effects such as:

  • Confusion
  • Tremors
  • Hyperactivity
  • Coma
  • Death

MAOIs also shouldn't be combined with drugs that constrict blood vessels such as epinephrine, amphetamines, pseudoephedrine, or ephedrine. It could increase one's blood pressure to dangerous levels.

All MAOIs should be discontinued at least two weeks before one is to be prescribed any medications that could interact with them. The effects of fluoxetine last for several weeks after the medication is discontinued, so it is recommended that a patient on fluoxetine waits at least five weeks before taking an MAOI.

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