MAOI (monoamine oxidase inhibitor) Antidepressants
Monamine oxidase inhibitors were the first medications marketed as antidepressants. They were developed in the 1940's and are still in use. They have been largely supplanted by other antidepressants that have fewer side effects, but there are still some situations where a MAOI is indicated. They are used to treat:
- Atypical depression, especially where there is extreme sensitivity to the environment or to rejection
- Anergic bipolar depression (low energy)
- Depression that has not responded to other antidepressants.
MAOIs are also used to treat panic disorder and other conditions.
How MAOIs work
Depression is thought to be related to an imbalance of brain chemicals, especially serotonin, dopamine and norepinephrine. These chemicals carry messages between nerve cells. They are released into the space between two nerve cells, and they bind with specific sites on the cell membrane of the receiving cell. Any chemicals that don't bind with the receiving cell are broken down and returned to the first cell by an enzyme called monamine oxidase.
MAOIs inhibit monamine oxidase and keep it from breaking down the chemicals. That allows them to accumulate and helps restore the chemical balance.
Contraindications
Monamine oxidase inhibitors should not be taken if:
- You have recently taken another antidepressant (within the past 2-5 weeks, depending on the medication).
- You cannot follow a strict special diet.
- You have severe heart disease or have recently had a heart attack or stroke
- You have a seizure disorder.
- You have asthma or bronchitis.
- You have high blood pressure.
Side Effects
Most people have side effects when they are taking MAOIs. The side effects are usually mild and temporary, but they can be serious enough to warrant stopping the medication. The usual side effects of MAOIs are:
- Dry mouth
- Lightheadedness
- Low blood pressure, especially when first standing up
- Reduced tolerance for alcohol
- Weight gain
- Sleep problems
The most serious side effects of MAOIs are related to their potential for interaction with food and other medications. These are discussed in the next section.
Interactions
MAOIs interact with a wide range of foods, supplements and medications. Some of them are:
- Cold and allergy medicines, antihistamines, cough medicines
- Over the counter diet medications
- Antipsychotic medications
- Asthma medications
- Tranquilizers and sedatives
- Blood pressure medications
- Medications for heart dysrhythmias
- Seizure medications
- Medications for ADHD
- Cocaine and similar drugs
- Pain medications, especially meperdine (Demerol)
- Dextromethorphan (found in many cough and cold medications-can cause fatal interaction)
- Tryptophan
- Other antidepressants
- Tyramine-containing foods-see Appendix 1 for a list of tyramine containing foods.
Hypertensive crisis: Tyramine and MAOIs can produce a hypertensive crisis, where your blood pressure rises rapidly and becomes very high. This can result in a heart attack or stroke, and is a medical emergency.
Serotonin syndrome: MAOIs interact with other antidepressants and serotonergic medications because they both alter serotonin levels. A toxic reaction, serotonin syndrome, can occur. This is sometimes described as Neuroleptic Malignant Syndrome or as MAOI reaction. Characteristics include shaking and shivers, anxiety, tremors and sweating and can progress to very high fevers, seizures, cardiovascular collapse and death.
Withdrawal
As with other antidepressants, MAOIs must be withdrawn gradually. Abruptly stopping them can cause withdrawal symptoms that can be extremely uncomfortable.
Appendix 1: Tyramine-containing foods
Tyramine is found primarily in aged or fermented foods. The tyramine content rises as the food ages-something that has been in the refrigerator for a week has more tyramine than it did when it was fresh. One way to avoid tyramine is to eat very fresh foods.
Cheese and wine have more tyramine than other foods. Here is a list of other tyramine-containing foods.
- Cheese
- Beer or wine, including nonalcoholic varieties
- Canned meat
- Meat extracts
- Canned gravy
- Caviar
- Hard sausages
- Meat tenderizer
- Unrefrigerated, fermented, pickled, salted or dried fish
- Game meat, especially if aged
- Liver
- Aged meat
- Avocadoes
- Bananas
- Fava beans
- Figs
- Sauerkraut
- Soybean products (tofu, soy sauce, etc)
- Bouillon
- Meat, yeast and protein extracts
- Aspartame (possibly)