Approach Considerations
As with most toxic ingestions, the cornerstone of management of monoamine oxidase inhibitor (MAOI) toxicity is continuous monitoring, decontamination when clinically indicated, and meticulous supportive care. Patients with MAOI overdoses should be admitted to the hospital primarily because of the prolonged latent stage. All patients with suspected MAOI ingestion require 24 hours of intensive care unit (ICU) care or frequent monitoring in an inpatient facility. Any child with evidence of MAOI toxicity should be stabilized and transferred to a tertiary pediatric center.
Prehospital Care
Prehospital care for MAOI toxicity may include the following:
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Stabilization of vital signs - Intravenous fluids
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Treatment of seizure activity - Benzodiazepines
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Attention to airway maintenance
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Attention to temperature control
Emergency Department Care
Give careful attention to airway management. Endotracheal intubation is required in any patient with a decreasing level of consciousness or signs of impending respiratory failure.
Because of the potential for severe toxicity and lack of antidotes, aggressive decontamination is important. Consider activated charcoal decontamination in any patient who presents within 1 hour after the ingestion. However, decontamination with activated charcoal should be performed with caution and with attention to the possibility of airway compromise. Gastric lavage is reserved for patients with life-threatening overdoses (2-3 mg/kg) who present within 1 hour of the ingestion. Before proceeding with any decontamination, secure the patient's airway.
Because of the pharmacokinetics of MAOIs, extracorporeal removal, such as with hemodialysis or repeat doses of activated charcoal, is likely less effective to reduce MAOI levels.
Frequent measurements of temperature is recommended. If the patient is hyperthermic, decreasing the temperature rapidly (within 20-30 min) is imperative. Antipyretics and use of a cooling blanket are generally inadequate.
The best methods for cooling patients include increasing evaporative losses by wetting their skin with warm water and maintaining airflow over them with fans. Removing the patient's clothing and exposing the patient to room air may help. In extreme cases (temperature greater than 106ºF [41.1ºC], rigidity, altered mental status), packing the individual in ice or in a bath of ice water may prove lifesaving. [28]
Fluid therapy is of paramount importance. Patients may be significantly dehydrated from hyperthermia.
Treating the associated hypertension is usually not necessary and may actually be dangerous, because it may exacerbate the eventual hypotensive phase. If antihypertensive therapy is deemed necessary, use of a short-acting antihypertensive agent, such as nitroprusside, nitroglycerin, or phentolamine, is advisable. Avoid beta-blockers because they leave unopposed alpha stimulation.
Intravenous benzodiazepines are useful for agitation and seizure control. They also may help control the hypertension.
Hospital admission is recommended in a patient with a tyramine reaction if symptoms do not resolve within 6 hours of onset or if the episode was an intentional MAOI overdose. Maintain vigilance regarding recrudescence of fever and ongoing fluid requirements.
Consultations
Consult the regional poison control center or a local medical toxicologist (certified through the American Board of Medical Toxicology and/or the American Board of Emergency Medicine) to obtain additional information and patient care recommendations. Critical care management may be required for cardiovascular complications.
Diet
Patients taking MAOIs should not consume foods high in tyramine such as aged cheeses, red wines and draft or unpasteurized beers. However, processed cheeses, white wines and bottled or canned beer are generally low in tyramine and have low-risk for precipitating a hypertensive crisis in patients taking MAOIs. [29]
Prevention
Patients should be cautioned that taking MAOIs with a selective serotonin reuptake inhibitor (SSRI), serotonin-norepinephrine reuptake inhibitor (SNRI), or other MAOI significantly increases the risk of developing serotonin syndrome. [29]
