Which activity should the patient be cautioned to avoid while taking a monoamine oxidase inhibitor MAOI?

Introduction

Monoamine oxidase inhibitors (MAOI) are antidepressant drugs with efficacy similar to other classes of antidepressant drugs. Originally developed for treatment of tuberculosis, MAOI were the first clinically effective modern antidepressant drugs Healy (1998). Although MAOI are no longer first line drugs for treatment of unipolar depression due to complex, unpredictable and often severe interactions with many food-derived amines and drug interactions, this class of drugs is still in clinical use.

MAOI increase monoamine levels in CNS and the peripheral tissues by inhibition of monoamine oxidase, a flavin-containing mitochondrial enzyme. Two forms of MAO, type A and type B, are non-selectively inhibited by classical MAO I. MAO-A is found in norepinephrine and serotonin neurons and regulates metabolic degradation of serotonin and catecholamines. This is thought to be the site of therapeutic action in depression. Classical MAOI irreversibly inhibit MAO and therefore side effects, drug interactions, and food interactions persist as long as two to three weeks following discontinuation of drug. The biochemical effect of MAOI to elevate serotonin and norepinephrine levels occurs rapidly. However, the therapeutic relief of depression requires several weeks of daily treatment. Selective and reversible MAO-A inhibitors are effective in treating major depression without many of the drug and food interactions associated with classical MAOI Baldessarini (2001), Yamada and Yasuhara (2004).

MAO-B is found in brain and regulates degradation of dopamine. Selective MAO-B inhibitors are used in the treatment of Parkinson's Disease and Alzheimer's Disease.

Parkinsonism

The monoamine oxidase inhibitors can be used in patients who have Parkinson’s disease, for two reasons. First, this is a disorder in which depression is common. Secondly, the selective type B inhibitor selegiline was originally thought to benefit patients with parkinsonism, possibly by increasing brain dopamine concentrations [26].

However, a long-term study showed higher death rates in patients with early mild Parkinson’s disease taking combined selegiline and levodopa compared with those taking levodopa alone. The authors concluded that the combination of selegiline with levodopa offers no advantage to patients with early mild Parkinson’s disease, and that although selegiline may help symptoms in advanced Parkinson’s disease it is best avoided in patients with postural hypotension, frequent falls, confusion, and dementia [27].

Dental consequences of MAOI

MAOIs can cause serious drug and food interactions. Interactions most relevant for the practicing dentist include the prolongation and enhancement of the CNS effects of the opioid analgesics, barbiturates, and other CNS depressants. MAOIs given in conjunction with meperidine cause potentially fatal reactions, including hyperthermia, excitement, and seizures, in addition to reactions that resemble an opioid overdose. Meperidine should not be used concurrently or for several weeks after therapy with MAOIs. Other opioids, which are not similar chemically to meperidine, may be used with caution.

Hypotension can develop with the concomitant use of general anesthetics and MAOIs. It is prudent to discontinue the use of MAOIs for 2 weeks before surgery. Neither epinephrine nor levonordefrin is potentiated by inhibition of MAO activity.

Monoamine oxidase (MAO) inhibitors

MAO inhibitors are medications that inhibit enzymes that break down monoamine neurotransmitters such as dopamine, serotonin, and norepinephrine. The levels of these neurotransmitters in the brain and peripheral nervous system therefore increase. MAOIs have been shown in double-blind, placebo-controlled studies to be helpful in treating re-experiencing symptoms in PTSD. The use of MAO inhibitors is contraindicated in patients with comorbid substance use because of potential life-threatening interactions with illicit drugs and alcohol. Patients on MAOIs also must adhere to a special diet devoid of foods and beverages with tyramine (an amino acid that interacts with neurotransmitters increased by MAOIs) in order to avoid potentially dangerous side effects. Many patients are not willing or reliably able to restrict their diet in this manner.

False Transmitters and Monoamine Oxidase Inhibition

MAOIs are powerful drugs used to treat depression and Parkinson disease. They include phenelzine, iproclozide, isocarboxazid, tranylcypromine, selegiline, rasagiline, and moclobemide. MAO catalyzes the oxidation of monoamines such as norepinephrine, serotonin (MAO-A), phenylethylamine (MAO-B), and dopamine (MAO-A,B). Dietary amines (e.g., tyramine derived from fermentation processes in cheese, wine, and beer) can cause a hypertensive reaction in patients taking MAOIs. In the presence of MAOIs, tyramine displaces norepinephrine from synaptic vesicles, leading to profound hypertension. When an indirect-acting sympathomimetic drug such as ephedrine is administered, an exaggerated BP increase can occur, especially in the first weeks of therapy with an MAOI. With long-term use, there is downregulation of adrenergic receptors, and TCAs and selective serotonin reuptake inhibitors are usually continued through the perioperative period given their rapid excretion and long latency period for effectiveness.51 MAOIs require discontinuation before surgery to allow restoration of enzyme activity. Irreversible MAOIs should be discontinued 2 weeks before surgery or switched to a reversible MAOI (moclobemide), which needs to be stopped only 24 hours before surgery.52 Because dopamine is a substrate for MAO, it should be administered at much lower doses in patients taking an MAOI or TCA. Use of meperidine with an MAOI can lead to hypertension, convulsions, and coma. Because of their risk for lethal dietary and drug interactions, MAOIs are generally used only when patients are unresponsive to first-line antidepressants.

PROBLEM ANALYSIS

Monoamine Oxidase Inhibitors

Monoamine oxidase inhibitors (MAOIs) are a group of antidepressant drugs that inhibit the action of monoamine oxidase (Brooker 2008). Monoamine oxidase is an enzyme that breaks down neurotransmitters such as adrenaline, dopamine, norepinephrine, and serotonin.

Oral doses of essential oils increase the potential for an essential oil to have an effect on MAOIs (Tisserand & Young 2013). Eugenol inhibits monoamine oxidase A (MAOA) and there is a potential link between the antidepressant activity of eugenol and its MAOA inhibitory activity (Tao et al 2005). Large amounts (>50%) of eugenol are found in the essential oils from bud, leaf, and stem of clove (Syzygium aromaticum) and from cinnamon leaf (Cinnamomum verum). Therefore, these essential oils could affect MAOIs if taken orally.

Monoamine Oxidase Inhibitors

The MAOIs inhibit the action of monoamine oxidase, which catabolizes monoamines (norepinephrine, dopamine, and serotonin) both in the central nervous system (CNS) and elsewhere in the body (Table 3). Common side effects of these agents include orthostatic hypotension, insomnia, agitation, sedation, and sexual side effects. The most problematic aspect of these medications is the possibility of rapidly developing hypertension if a patient eats foods containing tyramine. Patients must avoid matured cheeses, dried meats, tap beers, sauerkraut, and soy sauce and other soy products. Drug interactions are also potentially dangerous with the MAOIs. Contraindicated drugs include SSRIs and other serotonergic acting drugs, meperidine, and sympathomimetics such as pseudoephedrine and dextromethorphan. An advantage of the MAOIs is their apparent better efficacy in the treatment of atypical depression compared to TCAs. Data are not conclusive in comparing MAOIs and SSRIs in the treatment of this condition. Overall, MAOIs are prescribed fairly infrequently.

Table 3. MONOAMINE OXIDASE INHIBITORS

Monoamine Oxidase Inhibitors

Monoamine oxidase inhibitors (MAOIs) inhibit the action of MAO enzymes, resulting in increased concentrations of serotonin, norepinephrine, and dopamine. The classic MAOIs (e.g., isocarboxazid, phenelzine, tranylcypromine) irreversibly inhibit both MAO-A and MAO-B enzymes. Insomnia and daytime sedation are commonly reported side effects (up to 62% and 42% of patients, respectively),13 but there are no placebo-controlled studies. The most impressive PSG finding is a marked decrease in REM sleep, including almost complete abolishment of REM sleep.14 TST is also decreased. Although multiple sleep latency test (MSLT) studies are lacking, actigraphic monitoring in a small group of patients confirmed periods of decreased daytime activity coincident with reported episodes of napping, possibly associated with poor nighttime sleep. Cognitive performance and psychomotor performance do not appear to be influenced by the classic MAOIs, but data are limited.12,15 The newer MAOIs reversibly or selectively inhibit the MAO-A enzyme, resulting in fewer severe adverse effects. Drugs of this type include moclobemide (not available in the United States) and selegiline. Subjective and PSG data suggest that insomnia is more likely with higher doses.16,17 Moclobemide may enhance cognitive function in depressed outpatients.15