So I’m quite anxious about my upcoming surgery especially as I am on an MAOI. I went through PsychoTropical’s website and made a handout for my surgeon and anesthesiologist about MAOIs and what can and cannot be safely used.

I’m just wondering if my handout has covered everything? It would be great to get feedback on if it’s too much too. I don’t want to be seen as an unruly patient but I also really don’t want to potentially have a drug interaction. Do you think I need to add all those antidepressants and TCAs? I don’t think they are used in surgery at all but I also don’t want to potentially leave anything out that could be harmful.

Interactions with MAOIs:

The main issue in anesthesia and post-operative care is the avoidance of drugs with serotonin reuptake inhibitor potency, particularly opioid analgesics.

In ‘uncomplicated’ anesthesia (not involving pressor agents), aside from avoiding any use of narcotic analgesics with SRI potency, there are no major problems or interactions.

For ‘major’ operations that might require treatment to raise or lower blood pressure there are some adjustments of dosage and agents that may be required, but there are no major obstacles or risks.

For instance, the hypotensive effect of MAOIs may potentiate blood pressure decreases with general anaesthesia or neuraxial anaesthesia.

The potentially risky interactions with MAOIs are: - Serotonin syndrome, caused by (S)SRIs MAOIs - Blood pressure elevation, caused by tyramine in food, or by the other releasers like ephedrine & pseudoephedrine.

Any drug that works as a serotonin reuptake inhibitor is potentially dangerous (possibly fatal) if combined with an MAOI.

The risk is that of serotonin toxicity, because some opioids act as weak serotonin reuptake inhibitors. If high and repeated doses are used in the presence of an MAOI severe serotonin toxicity is possible.

Avoid: - methylene blue MB (aka methylthioninium), even if only a dye (including intravenously) - meperidine (pethidine) - tramadol - tapentadol - methadone - dextromethorphan - dextropropoxyphene - pentazocine - ephedrine - pseudoephedrine - linezolid - sertraline - fluoxetine - paroxetine - fluvoxamine - citalopram - escitalopram - clomipramine - imipramine - milnacipran - venlafaxine - desvenlafaxine - duloxetine

With caution: - ketamine: Clinical doses of ketamine for used for induction of anaesthesia, maintenance of analgesia, or treatment of depression, do not result in serotonin re-uptake inhibition (SRI). Peak concentrations of ketamine when used for induction of anaesthesia may result in inhibition of norepinephrine reuptake and might theoretically result in exaggerated hypertension when used in the presence of MAO-A or non-selective MAO-AB inhibition. It is clearly prudent to continue monitor such combinations closely. - adrenaline (epinephrine) and noradrenaline (norepinephrine): they are direct post-synaptic agonists and therefore do not cause any problematic interaction with MAOIs. If vasopressor agents are required directly acting alpha agonists may have their effects potentiated — initial doses of norepinephrine (noradrenaline) and epinephrine (adrenaline) need to be lower when used in patients taking MAOIs. These initial lower doses may then be promptly titrated as needed, without significant difficulty or inconvenience. - phenylephrine: initial doses of phenylephrine need to be lower when used in patients taking MAOIs. These initial lower doses may then be promptly titrated as needed, without significant difficulty or inconvenience. Care may be required where copious amounts of ‘topical’ phenylephrine are used to control bleeding vascular beds - hypertension and vascular incidents have been reported even in the absence of MAOIs. Oxymetazoline may be a better option.

Safe: - NSAIDs and all other non-opioid painkillers - codeine - oxycodone - hydrocodone - buprenorphine - morphine - remifentanil - alfentanil - sufentanil - fentanyl - dexmedetomidine - ondansetron - mirtazapine - mianserin - trazodone - reboxetine - oxymetazoline - xylometazoline