Monoamine oxidase inhibitor toxicity: Difference between revisions
| Line 3: | Line 3: | ||
*Used to treat depression and Parkinsonism (e.g. selegiline) | *Used to treat depression and Parkinsonism (e.g. selegiline) | ||
*Lead to increased norepinephrine, serotonin, dopamine, tyramine | *Lead to increased norepinephrine, serotonin, dopamine, tyramine | ||
*Linezolid is a reversible inhibitor of MAO and produces significant inhibition of MAO-A | |||
===Toxicity Mechanisms=== | ===Toxicity Mechanisms=== | ||
| Line 8: | Line 9: | ||
**Symptoms often delayed 6-24 hours after ingestion | **Symptoms often delayed 6-24 hours after ingestion | ||
*Food-drug interactions | *Food-drug interactions | ||
**Taking MAOI at therapeutic doses, but inadvertently eating foods rich in tyramine (aged cheese, red wine) | **Taking MAOI at therapeutic doses, but inadvertently eating foods rich in tyramine (aged cheese, red wine, aged meats) | ||
**Symptoms are generally acute | **Symptoms are generally acute | ||
*Drug-drug interactions | *Drug-drug interactions | ||
Revision as of 13:28, 1 September 2019
Background
- MonoAmine Oxidase Inhibitors (MAOI)
- Used to treat depression and Parkinsonism (e.g. selegiline)
- Lead to increased norepinephrine, serotonin, dopamine, tyramine
- Linezolid is a reversible inhibitor of MAO and produces significant inhibition of MAO-A
Toxicity Mechanisms
- Intentional overdose
- Symptoms often delayed 6-24 hours after ingestion
- Food-drug interactions
- Taking MAOI at therapeutic doses, but inadvertently eating foods rich in tyramine (aged cheese, red wine, aged meats)
- Symptoms are generally acute
- Drug-drug interactions
- Many prescription and OTC medications interact with MAOI
Types
- MAO-A
- Primarily deaminates serotonin and norepinephrine
- MOA-B
- Primarily deaminates phenylethylamine
Clinical Features
- Similar to hyperadrenergic state
- Severe toxicity accompanied by coma, seizure, bradycardia, hypotension, worsening hyperthermia
Differential Diagnosis
- Intoxications
- Amphetamines
- Antimuscarinics
- St. John's Wort
- Withdrawal states
- Ethanol
- Clonidine
- Beta-blockers
- Medical conditions
- Adverse drug reactions
Evaluation
- asymptomatic period followed by delayed toxicity can suggest MAO-I toxicity
- urine immunoassays and mass spectroscopy can fail to detect MAOI
- consider ECG and chemistry panel in MAOI overdose patients who are obtunded
Management
- Gastric decontamination
- Activated charcoal PO x 1
- Consider gastric lavage, if can be performed <1 hour after ingestion
- Supportive care
- Hypertension
- Treat only with short-acting agents: may develop precipitous hypotension
- Phentolamine: 2.5-5mg IV bolus q15-15min; can also give as infusion 0.2-0.5mg/min
- Nitroprusside: 1mcg/kg/min and titrate up
- Hypotension: intravenous fluid +/- norepinephrine
- Seizures: benzodiazepines are 1st line
- Hyperthermia
- Routine cooling measures
- Consider paralysis if patient has persistent muscle rigidity
- Hypertension
Disposition
- Admit all patients for 24 hour observation to monitored setting
Prevention
- Do not prescribe the following medications if a patient is taking a MAOI: meperidine, dextromethorphan, tramadol, propoxyphene, or cyclobenzaprine
See Also
References
- Rosen's