MAOI (Monoamine Oxidase Inhibitors) Therapy 

 

 

Background 

 

  • Inhibit breakdown of norepinephrine & serotonin, & also inhibit hepatic microsomal enzymes.  These may result in:

    • Risk of hypertensive crisis with norepinephrine release 

    • CNS 'type I' reaction: risk of serotonin syndrome under certain conditions resulting in agitation, headache, fever, seizures, coma, & death

    • CNS 'type II' reaction: ↓ hepatic opioid metabolism & thus opioid build-up causing sedation, respiratory depression, & cardiovascular collapse 

 

 

Considerations

 

  • Indication for MAOIs: depression, anxiety, psychosis, hypotension, narcolepsy, headache

  • Continuation vs discontinuation of MAOI pre-op:

    • ​May need to consult prescribing physician (psychiatry, neurology) 

    • If possible, try to discontinue 2 weeks pre-op with a tapering regimen 

    • If cannot discontinue: be mindful of systemic effects below & avoid inpatient diets containing high amounts of tyramine 

  • Risk of severe hypertension if sympathetic stimulation or sympathomimetic drugs:

    • Avoid light anesthesia 

    • Avoid ketamine, pancuronium 

    • Avoid indirect acting vasopressors such as ephedrine 

    • Avoid foods contaning high amounts of tyramine (cheese, wine)

  • Risk of CNS adverse reactions:

    • ​Type I reaction leading to serotonin syndrome: avoid anticholinergics & meperidine 

    • Type II reaction from accumulation of opioids: need to monitor closely for adverse events, opioid use not necessarily contraindicated & have been safely used 

  • Altered response to anesthetic agents:

    • ↑ MAC due to ↑ concentrations of CNS norepinephrine

    • Possible prolonged succinylcholine effect

    • Exaggerated hypotension with neuraxial techniques

    • Direct acting vasopressors only, consider ↓ doses

 

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