Monoamine oxidase inhibitor toxicity: Difference between revisions
| Line 28: | Line 28: | ||
**[[Amphetamines]] | **[[Amphetamines]] | ||
**[[Antimuscarinics]] | **[[Antimuscarinics]] | ||
**Methylxanthine toxicity (theophylline, caffeine) | |||
**St. John's Wort | **St. John's Wort | ||
*Withdrawal states | *Withdrawal states | ||
**[[Ethanol withdrawal|Ethanol]] | **[[Ethanol withdrawal|Ethanol]] | ||
**[[Benzodiazepine withdrawal]] | |||
**Clonidine | **Clonidine | ||
**Beta-blockers | **Beta-blockers | ||
| Line 37: | Line 39: | ||
**[[Hypoglycemia]] | **[[Hypoglycemia]] | ||
**[[Hyperthyroidism]] | **[[Hyperthyroidism]] | ||
**[[Meningitis]] | |||
**[[Encephalitis]] | |||
**[[Pheochromocytoma]] | |||
**[[Carcinoid syndrome]] | |||
*Adverse drug reactions | *Adverse drug reactions | ||
**[[Malignant Hyperthermia]] | **[[Malignant Hyperthermia]] | ||
Revision as of 13:33, 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 (tachycardia, hypertension, hyperthermia)
- Severe toxicity accompanied by coma, seizure, bradycardia, hypotension, worsening hyperthermia, rhabdomyolysis
Differential Diagnosis
- Intoxications
- Amphetamines
- Antimuscarinics
- Methylxanthine toxicity (theophylline, caffeine)
- St. John's Wort
- Withdrawal states
- Ethanol
- Benzodiazepine withdrawal
- 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