How MAOIs Work
The brain's neurotransmitters serotonin, norepinephrine and dopamine are all monoamines, meaning they have a single amino acid group. In the gap between nerve cells - the synapse - used neurotransmitters are destroyed by an enzyme called monoamine oxidase (MAO). If this results in too low concentrations of neurotransmitters, depression can result. MAOIs work by blocking the activity of this enzyme, resulting in higher levels of neurotransmitters in the brain, relieving depression.
Which Drugs Are MAOIs?
MAOI antidepressants include:
- Marplan - generic isocarboxazid
- Nardil - phenelzine
- Parnate - tranylcypromine
- Manerix - moclobemide (available outside the United States)
- Emsam - see below
The enzyme monoamine oxidase has another role in the brain - it controls levels of tyramine, which affects blood pressure. When an MAOI blocks the activity of the MAO enzyme, along with higher levels of neurotransmitters, it causes higher levels of tyramine, and blood pressure can go up. A high spike in tyramine can lead to a sudden jump in blood pressure, called a hypertensive crisis, which can lead to stroke and death.
Thus foods high in tyramine are off-limits to people taking MAOIs. For more, see MAOIs and Diet.
Many drugs - prescription medications, over-the-counter drugs and street drugs - should be avoided when taking an MAOI antidepressant. The most common of these include:
- Allergy, cold, cough and sinus medications (including nasal sprays/drops)
- Asthma drugs
- Blood pressure medications
- Other antidepressants not specifically listed, including other MAOIs
- Tricyclic antidepressants*
The general rule of thumb when changing between an MAOI and another antidepressant is to wait two weeks between stopping one and starting the other. However, because Prozac is slow to leave the body, at least five weeks should be allowed between stopping Prozac and starting an MAOI to avoid possibly lethal complications.
It is vital that you tell your doctor about all drugs of all kinds you are taking or take as needed when you discuss starting an MAOI. To be safe when taking an MAOI, do not take any prescription or over-the-counter medication without first checking with your doctor.
Other Precautions and Warnings
- Safety has not been established for MAOIs during pregnancy and while breastfeeding; thus, use is not recommended.
- Elderly patients are more likely to experience dizziness or lightheadedness while taking one of these medications.
- Insulin dosage may need to be adjusted when taking an MAOI.
- Persons taking Nardil should not use the artificial sweetener aspartame.
- Unless you are experiencing severe side effects, do not stop taking an MAOI abruptly. Work with your doctor to taper off the medication gradually.
Stop taking your MAOI and get emergency help immediately if you experience any of the following symptoms of a hypertensive crisis:
- Severe chest pain; severe headache; stiff or sore neck; enlarged pupils; fast or slow heartbeat; increased sensitivity of eyes to light; increased sweating (possibly with fever or cold, clammy skin); nausea and vomiting.
Emsam - MAOI Without Dietary Restrictions at Lowest Dose
Emsam - generic selegiline - was approved for use by the US Food and Drug Administration in February 2006. Emsam is a patch, not a pill, and thus at the lowest dose (6 mg per day) does not interact with food as do oral MAOIs. According to the FDA's press release announcing Emsam's approval, "The only common side effect of Emsam detected in placebo-controlled trials was a mild skin reaction where the patch is placed. There may be mild redness at the site when a patch is removed. If the redness does not go away within several hours after removing the patch or if irritation or itching continues, patients are advised to contact their doctor. Another side effect that was seen less commonly was light-headedness related to a drop in blood pressure."
Disclaimer: This is not intended to be all-inclusive or to replace information provided by your doctor or with prescriptions from drug manufacturers.
HealthyPlace.com. (2006). Monoamine Oxidase Inhibitors. Retrieved August 4, 2006.
Medline Plus. (2005). Antidepressants, Monoamine Oxidase (MAO) Inhibitor (Systemic). 8/4/06.
US Food and Drug Administration. (2006). FDA Approves Emsam (Selegiline) as First Drug Patch for Depression. Retrieved August 4, 2006, from http://www.fda.gov/bbs/topics/NEWS/2006/ NEW01326.html.
Wikipedia (2006) Monoamine Oxidase Inhibitor. Retrieved August 4, 2006, from http://en.wikipedia.org/wiki/ Monoamine_oxidase_inhibitor.
Wikipedia (2006) Atypical Depression. Retrieved August 5, 2006, from http://en.wikipedia.org/wiki/ Atypical_depression.