MAOI - MonoAmine Oxidase Inhibitor (Wiki)

Please note: Dosage equivalents are provided for certain drugs below and are denoted as unit equivalents, i.e. one unit of drug x is roughly the equivalent as one unit of drug y, where the dosage equal to one unit varies.

MAOI medications were the first discovered family of antidepressants. The drug irponiazid, originally intended as a treatment for tuberculosis, was discovered as an antidepressant in the early to mid 1950s when researchers noted that the drug made patients "inappropriately happy". It was officially launched as an antidepressant in 1958 and the medicinal revolution began.

Due to the dangers outlined below, MAOI antidepressants are certainly not first line treatments; they are reserved for patients who do not respond adequately to both selective reuptake inhibiters and tricyclic drugs. They are also used in cases of extreme clinical depression. Simply put, MAOI antidepressants are more powerful, more reliable and more guaranteed to work than any other antidepressant family in production today - if these drugs don't help you, it is highly unlikely that any drug will.

MAOI antidepressants work by permanently binding with monoamine oxidase enzymes, thereby preventing them from breaking down monoamine neurotransmitters, notably serotonin, noradrenaline and dopamine. Unfortunately, in doing so a chemical called tyramine that is found in many different types of food is in turn not broken down, which is potentially very dangerous; as the chemical builds up, so does noradrenaline, meaning that the blood pressure in the patient sky rockets, an event known as a hypertensive crisis, something that can all too easily result in a stroke; the most obvious warning sign is a severe headache, described as "the worst pain ever". A less well known risk is that of a condition known as a hyperpyrexia (a spike in body temperature) which can be incurred by eating levodopa rich foods.

As a result, patients treated with MAOI antidepressants should follow a strict diet. Technically, the tyramine reaction (often dubbed as the "cheese reaction" as most cheeses are especially rich in tyramine) only effects one in four people, but at this time there is no safe way to find out if you are one of the lucky three in four who will mostly escape the regime.

Monoamine oxidase enzymes are split into two isoforms, MAO-A and MAO-B. MAO-A chiefly breaks down serotonin, melatonin, adrenaline and noradrenaline, whilst MAO-B breaks down phenylethylamine and trace amines; dopamine seems to be pretty evenly spread over the two of them. Some MAOI drugs favour one enzyme over the other, but most inhibit both.

Monoamine oxidase inhibitors in general aren't the smartest things to combine with other antidepressants or for that matter other drugs in general. In particular, they should not be mixed with antidepressants that inhibit the reuptake of serotonin for fear of inducing a potentially fatal condition known as serotonin syndrome; this can also be brought about by eating too much tryptophan rich food. Additionally, many antidepressants such as tricyclics can cause, just as tyramine can, a hypertensive crisis. Emergency medications that you may be given in hospital aren't good things to be given either, so you might want to carry a medical alert on your person.

Typically, your doctor will give you a small amount of an antidote that will combat and hopefully avert any hypertensive crisis by lowering your blood pressure; one example is a drug called nifedipine (marketed as Adalat®) which can be supplied as liquid capsules; pop one in your mouth, bite it and the drug will be absorbed extremely quickly indeed, kind of like an injection. Also ensure that you have a copy of the MAOI diet at hand - honestly, you don't want to find out whether your meal is tyramine rich or not the hard way.

"The monoamine oxidase inhibitors—chiefly isocarboxazid, phenelzine, and tranylcypromine—in general are used only after treatment with tricyclic drugs has proved unsatisfactory, because these drugs' side effects are unpredictable and their complex interactions are incompletely understood. The MAOs apparently achieve their effect by interfering with the action of monoamine oxidase, an enzyme that is involved with the breakdown of norepinephrine, serotonin, and dopamine within nerve cells." - Encyclopædia Britannica

Clorgiline/Clorgyline (Wiki)

Brand names: None known
Formula: C13H15Cl2NO
Half life: Unknown
Single unit dose: Unknown
Recommended outpatient dose: Unknown
Maximum outpatient dose: Unknown

Clorgiline is a selective, non-reversible MAOI medication that favours MAO-A inhibition over MAO-B. It is structurally related to Pargyline; it has antidepressant qualities and can be helpful in the fight against Parkinson’s Disease.

Iproclozide (Wiki)

Brand names: Sursum®
Formula: C11H15ClN2O2
Half life: Unknown
Single unit dose: Unknown
Recommended outpatient dose: 10mg per day [Not Verified]
Maximum outpatient dose: 30mg per day [Not Verified]

I have no information on this drug at this time.

Iproniazid (Wiki)

Brand names: Ipronid®, Iprozid®, Marsilid®, Propilniazida®, Rivivol®
Formula: C9H13N3O
Half life: ~ 10 hours
Single unit dose: Unknown
Recommended outpatient dose: Unknown
Maximum outpatient dose: Unknown

The first antidepressant drug ever to be marketed was in fact originally intended as a treatment for tuberculosis; its antidepressant effects were discovered when researchers noted that patients given iproniazid became "inappropriately happy"; it was released in 1958.

Isocarboxazid (Wiki)

Brand names: Marplan®
Formula: C12H13N3O2
Half life: ~ 2.5 hours
Single unit dose: Unknown
Recommended outpatient dose: 30mg per day [Verified]
Maximum outpatient dose: 60mg per day [Verified]

Approved for the treatment of major depressive disorders, isocarboxazid is a staple final line of defence drug for depression. In 1988 it was further found to be effective in the treatment of bulimia, regardless of whether a depressive disorder is present or not.

Minaprine (Wiki)

Brand names: None known
Formula: C17H22N4O
Half life: Unknown
Single unit dose: Unknown
Recommended outpatient dose: Unknown
Maximum outpatient dose: Unknown

Minaprine is a short acting, weak inhibitor of MAO-A, preferring said MAO over MAO-B.

Nialamide (Wiki)

Brand names: Delmoneurina®, Espril®, Isalizina®, Mygal®, Nialamid®, Niamid®, Niamidal®, Niamide®, Niaquitil®, Niazin®, Novazid®, Nuredal®, Nyazin®, Nyezin®, Psicodisten®, Surgex®
Formula: C16H18N4O2
Half life: Unknown
Single unit dose: Unknown
Recommended outpatient dose: Unknown
Maximum outpatient dose: Unknown

One of the first MAOI drugs to be developed, nialamide is chemically similar to iproniazide, another drug of the same class. It is especially effective in the treatment of reactive depression, endogenous depression and depression characterissed by anergic symptoms; it can also be used to treat trigeminal neuralgia and is being studied as a treatment for alcoholism, angina, cerebrovascular disorders, dermatomally distributed vitiligo, irregular menstrual cycle and as a preventative measure for streptomycin-induced deafness. The drug is a stimulant and is therefore especially effective in the treatment of melancholic depressive states.

Common side effects include a dry mouth, nausea and/or vomiting, constipation, vertigo, insomnia, weight gain, hyperhidrosis, tachycardia, a decrease in systolic pressure and orthostatic hypotension.

Pargyline (Wiki)

Brand names: None known
Formula: C11H13N
Half life: Unknown
Single unit dose: Unknown
Recommended outpatient dose: Unknown
Maximum outpatient dose: Unknown

Pargyline is a selective, non-reversible inhibitor of MAO-B. Although it is not used as an antidepressant, it does exhibit some mild antidepressant qualities. Compared to Clorgyline, Pargyline had a weaker antidepressant effect and exhibited more side effects. Typically, the drug has an activating quality.

Phenelzine (Wiki)

Brand names: Nardil®
Formula: C8H12N2
Half life: ~ 1.2 hours
Single unit dose: Unknown
Recommended outpatient dose: 45mg per day [Verified]
Maximum outpatient dose: 90mg per day [Verified]

Despite a markedly short half life, phenelzines effects can last for weeks due to its mode of action, irreversibly inhibiting MAO-A and MAO-B. Common side effects include fatigue, dizziness, headaches, gastro-intestinal disturbances and orthostatic hypotension. It can also cause, albeit rarely, major hepatotoxity. Experts estimate that approximately 80,000 people are currently taking this medication worldwide at time of writing.

Selegiline (Wiki)

Brand names: Anipryl® (veterinary), Eldepryl®, Emsam® (patch)
Formula: C13H17N
Half life: ~ 2 hours
Single unit dose: Unknown
Recommended outpatient dose: Unknown
Maximum outpatient dose: Unknown

Although primarily a treatment for Parkinsons Disease, selegiline does have antidepressant qualities, especially at higher doses. At normal doses the drug is selective, opting to inhibit MAO-B over MAO-A, meaning that at these doses dietry restrictions the apply to most MAOI drugs are not wholly necessary; however, at higher doses selegiline loses this selectivity and begins to inhibit both MAO-A and MAO-B.

This medication appears to have a stimulant effect and as such is sometimes used as a treatment for narcolepsy. Although its side effects are pretty similar to those of other MAOI drugs, selegiline has one interesting characteristic that is pretty contrary to the effect generated by virtually every other antidepressant: selegiline stimulates one's libido, especially in men.

Selegiline returned to popularity recently at time of writing when it was successfully applied to a patch to combat depression. At low doses dietary restrictions are fairly lax and by this token the MAOI drug family is more accessible to depressed individuals. At the time of writing, the patch (Emsam) is receiving mixed reviews.

Tranylcypromine (Wiki)

Brand names: Parmodalin®, Parnate®, Sicoton®, Transamin®, Transapin®, Tylciprine®
Formula: C9H11N
Half life: ~ 4.4 to 8 hours (vague figure)
Single unit dose: Unknown
Recommended outpatient dose: 20mg per day [Verified]
Maximum outpatient dose: 60mg per day [Not Verified]

A fast acting antidepressant, tranylcypromine is not recommended for the treatment of depressive disorders where melancholia is present.