Isocarboxazid, Phenelzine, Tranylcypromine |
Issues for Surgery |
Risk of withdrawal symptoms and risk of relapse if omitted (see Further Information). Risk of serotonin syndrome if continued, or if any doses taken in previous 2 weeks (see Interaction(s) with Common Anaesthetic Agents and Interaction(s) with other Common Medicines used in the Perioperative Period). Risk of hypertensive crisis if continued, or if any doses taken in previous 2 weeks (see Interaction(s) with Common Anaesthetic Agents and Interaction(s) with other Common Medicines used in the Perioperative Period).) |
Advice in the Perioperative period |
Elective Surgery Plan elective surgery with Anaesthetist and patient’s Psychiatrist at earliest opportunity. The patient should be involved in these discussions1. If continuing MAOI
Consider premedication with benzodiazepines to reduce stress as stress may lead to sympathetic stimulation1. If stopping MAOI Emergency Surgery Inform Anaesthetist if patient received any doses of irreversible MAOI in last 2 weeks1, 6. MAOI-safe anaesthesia will need to be used, avoid: -
Consider premedication with benzodiazepines to reduce stress as stress may lead to sympathetic stimulation1. Post-operative Advice If discontinued pre-operatively restart as soon as possible after the operation, once there is no longer a risk of interactions1. If switched to an alternative antidepressant pre-operatively follow management plan from patient’s Psychiatrist. If continue pre-operatively be alert to potential interactions (see Interaction(s) with Common Anaesthetic Agents and Interaction(s) with other Common Medicines used in the Perioperative Period). If a long nil by mouth (NBM) period is anticipated, or if there are concerns with enteral absorption, advice on alternative preparations / routes should be sought from a Psychiatrist. |
Interaction(s) with Common Anaesthetic Agents |
Anaesthesia General and regional anaesthesia can be given safely to patients taking MAOIs provided there is proper monitoring, adequate preparation and prompt recognition (and treatment) of anticipated and predictable reactions5. Certain drugs should be avoided or used with extreme caution. Inhalational anaesthetics (e.g. isoflurane and nitrous oxide) are all safe in the presence of MAOIs (although there is a theoretical risk of hepatic damage with halothane, which is no longer used in the UK)1, 6. Intravenous induction agents (thiopental, propofol, etomidate and ketamine) have also been used without problem in patients taking MAOIs5. However, ketamine should ideally be avoided due to potential sympathetic stimulation, although no interactions have been reported6. A dose reduction may be necessary for barbiturates due to reduced hepatic metabolism1. Hypotension may occur following spinal anaesthesia in patients taking phenelzine or tranylcypromine due to an additive hypotensive effect2, 4. Sympathomimetics Vasopressors Directly-acting sympathomimetics (e.g. adrenaline / epinephrine, isoprenaline, noradrenaline / norepinephrine and phenylephrine) can be used safely in patients taking MAOIs, however, caution is advised as the effect is likely to be intensified and prolonged due to receptor hypersensitivity in those patients who have a hypotensive response to MAOIs1, 5, 6. Doses should be carefully titrated. The manufacturers of dopamine recommend that the initial dose is reduced to one tenth of the normal dose and great care is taken8. The response to parenteral phenylephrine is approximately doubled, and whilst the UK manufacturer contraindicates concurrent use, the US manufacturer does not5. Hypotension should initially be treated with fluids and then with cautious doses of directly-acting sympathomimetics titrated carefully against clinical response1. Local Anaesthetics Opioids CNS Excitation (Serotonin Syndrome)
CNS Depression (Opioid Toxicity) Recommendations Morphine, codeine, oxycodone and buprenorphine are not thought to be inhibitors of serotonin reuptake so are preferred opioids for patients taking MAOIs, however caution is advised9. Morphine appears to be the strong opioid of choice – start with a low dose (a third to a half the normal dose) and titrate to clinical response6, 9. Monitor the patient carefully for any signs of adverse effects, particularly blood pressure and signs and symptoms of CNS and respiratory depression9. Neuromuscular Blocking Drugs (NMBDs) Phenelzine prolongs the effects of suxamethonium by decreasing plasma cholinesterase concentrations1, 5, 6. Pancuronium should be avoided due to the release of stored noradrenaline. Atracurium appears to be a suitable alternative6. |
Interaction(s) with other Common Medicines used in the Perioperative Period |
CNS Excitation (Serotonin Syndrome) For a discussion of opioids see under Interaction(s) with Common Anaesthetic Agents above. There is also an increased risk of developing serotonin syndrome when MAOIs are used concurrently with the following5: -
Nefopam Nefopam has sympathomimetic activity and may precipitate hypertensive crisis; the concurrent use of nefopam and an MAOI is contraindicated5, 7. |
Further Information |
Withdrawal MAOIs are associated with withdrawal symptoms on cessation of therapy1, 2. Withdrawal effects may occur within 5 days of stopping treatment and are usually mild and self-limiting but in cases may be severe7. Symptoms include agitation, irritability, ataxia, movement disorders, insomnia, drowsiness, vivid dreams, cognitive impairment, and slowed speech. Withdrawal symptoms occasionally experienced when discontinuing MAOIs include hallucinations and paranoid delusions7. If possible MAOIs should be withdrawn slowly over at least 4 weeks. The risk of withdrawal is increased if MAOIs are stopped suddenly after regular administration for more than 8 weeks7. Relapse In addition to the withdrawal effects stopping MAOIs prematurely is associated with a significant risk of relapse. In one study nearly 40% of patients switched from phenelzine to a placebo relapsed within four weeks, with half of those relapsing within two weeks1. Switching to Moclobemide It has been suggested that patients on irreversible MAOIs could switch to moclobemide, a reversible MAOI, two weeks pre-operatively allowing treatment to continue until the day before surgery10. Some sources advise that irreversible MAOIs should be tapered then stopped for 2 weeks before starting moclobemide10, 11, however, other sources indicate a gap is not needed providing MAOI dietary restrictions are maintained for 10-14 days after switching12. Such switches should ONLY be instigated by the patient’s psychiatrist. Dietary Restrictions Potentially life-threatening hypertensive crisis can develop in those taking MAOIs who eat tyramine-rich food (e.g. mature cheese, salami, pickled herring, Bovril®, Oxo®, Marmite® or any similar meat or yeast extract or fermented soya bean extract, and some beers, lagers or wines) or foods containing dopa (such as broad bean pods). Patients should avoid tyramine or dopa-rich food or drinks whilst taking irreversible MAOIs (and for 2 to 3 weeks after stopping irreversible MAOIs)7.
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References |
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