Monoamine oxidase inhibitor toxicity: Difference between revisions
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==Background== | ==Background== | ||
* | *MonoAmine Oxidase Inhibitors (MAOI) | ||
*Used to treat depression and Parkinsonism ( | *Used to treat depression and Parkinsonism | ||
*MAOI drugs available in the US include: | |||
**Isocarboxazid, phenelzine (Nardil), tranylcypromine (Parnate) | |||
**Selegiline (Deprenyl, Eldepryl, Emsam, Zelapar)--> MAO-B at lower doses, MAO-A at higher doses, rasagiline (Azilect), safinamide (Xadago) | |||
**[[Linezolid]] is a reversible inhibitor of MAO and produces significant inhibition of MAO-A | |||
**[[Methylene blue]]<ref>Petzer A, Harvey BH, Wegener G, Petzer JP (February 2012). "Azure B, a metabolite of methylene blue, is a high-potency, reversible inhibitor of monoamine oxidase". Toxicology and Applied Pharmacology. 258 (3): 403–9. </ref> | |||
*Lead to increased norepinephrine, serotonin, dopamine, tyramine | *Lead to increased norepinephrine, serotonin, dopamine, tyramine | ||
==Clinical Features | ===Toxicity Mechanisms=== | ||
*Similar to hyperadrenergic state | *Intentional overdose | ||
*Severe toxicity accompanied by coma, seizure, bradycardia, hypotension, worsening hyperthermia | **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== | ==Differential Diagnosis== | ||
*Intoxications | *Intoxications | ||
**Amphetamines | **[[Amphetamines]] | ||
**Antimuscarinics | **[[Anticholinergic toxicity|Antimuscarinics]] | ||
**Methylxanthine toxicity ([[theophylline toxicity|theophylline]], [[caffeine toxicity|caffeine]]) | |||
**St. John's Wort | |||
*Withdrawal states | *Withdrawal states | ||
**Ethanol | **[[Ethanol withdrawal|Ethanol]] | ||
**Clonidine | **[[Benzodiazepine withdrawal]] | ||
**Beta-blockers | **[[Clonidine]] | ||
**[[Beta-blockers]] | |||
*Medical conditions | *Medical conditions | ||
**Heat stroke | **[[Heat stroke]] | ||
**Hypoglycemia | **[[Hypoglycemia]] | ||
**Hyperthyroidism | **[[Hyperthyroidism]] | ||
**[[Meningitis]] | |||
**[[Encephalitis]] | |||
**[[Pheochromocytoma]] | |||
**[[Carcinoid syndrome]] | |||
*Adverse drug reactions | *Adverse drug reactions | ||
**[[Malignant Hyperthermia]] | **[[Malignant Hyperthermia]] | ||
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**[[Neuroleptic Malignant Syndrome (NMS)]] | **[[Neuroleptic Malignant Syndrome (NMS)]] | ||
== | {{Movement disorder DDX}} | ||
*Gastric decontamination | |||
** | ==Evaluation== | ||
*Asymptomatic period followed by delayed toxicity can suggest MAO-I toxicity | |||
*urine immunoassays and mass spectroscopy can fail to detect MAOI (patients taking selegiline will test positive for methamphetamine) | |||
*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]] | |||
#*CNS excitation and [[Seizures]]: [[benzodiazepines]] are 1st line | |||
#*Hyperthermia | |||
#**Routine cooling measures | |||
#**Consider paralysis if patient has persistent muscle rigidity | |||
==Prevention== | |||
*Do ''not'' prescribe the following medications if a patient is taking a MAOI: [[meperidine]], [[dextromethorphan]], [[tramadol]], propoxyphene, or [[cyclobenzaprine]] | |||
==Disposition== | ==Disposition== | ||
*Admit all patients for 24 hour observation to monitored setting | *Admit all patients for 24 hour observation to monitored setting (risk of delayed hyperadrenergic symptoms) | ||
==See Also== | ==See Also== | ||
Line 53: | Line 88: | ||
==References== | ==References== | ||
*Rosen's | |||
[[Category: | [[Category:Toxicology]] |
Latest revision as of 13:45, 14 November 2020
Background
- MonoAmine Oxidase Inhibitors (MAOI)
- Used to treat depression and Parkinsonism
- MAOI drugs available in the US include:
- Isocarboxazid, phenelzine (Nardil), tranylcypromine (Parnate)
- Selegiline (Deprenyl, Eldepryl, Emsam, Zelapar)--> MAO-B at lower doses, MAO-A at higher doses, rasagiline (Azilect), safinamide (Xadago)
- Linezolid is a reversible inhibitor of MAO and produces significant inhibition of MAO-A
- Methylene blue[1]
- Lead to increased norepinephrine, serotonin, dopamine, tyramine
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
- Medical conditions
- Adverse drug reactions
Movement Disorders and Other Abnormal Contractions
- Chorea
- Neuroleptic malignant syndrome
- Serotonin syndrome
- Hypocalcemia
- Strychnine toxicity
- Acute tetanus
- Parkinson's disease
- Mono amine oxidase inhibitor toxicity
- Phencyclidine toxicity
- Anti-NMDA receptor encephalitis
- Huntington disease
- Wilson's disease
- CVA
- Schizophrenia
- Psychotic agitation
- Dementia
- Lewy body dementia
- Vascular dementia
- Frontotemporal dementia
- Dystonic reaction
- Extrapyramidal reaction
- Torticollis
- Idiopathic movement disorder
Evaluation
- Asymptomatic period followed by delayed toxicity can suggest MAO-I toxicity
- urine immunoassays and mass spectroscopy can fail to detect MAOI (patients taking selegiline will test positive for methamphetamine)
- 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
- CNS excitation and Seizures: benzodiazepines are 1st line
- Hyperthermia
- Routine cooling measures
- Consider paralysis if patient has persistent muscle rigidity
- Hypertension
Prevention
- Do not prescribe the following medications if a patient is taking a MAOI: meperidine, dextromethorphan, tramadol, propoxyphene, or cyclobenzaprine
Disposition
- Admit all patients for 24 hour observation to monitored setting (risk of delayed hyperadrenergic symptoms)
See Also
References
- Rosen's
- ↑ Petzer A, Harvey BH, Wegener G, Petzer JP (February 2012). "Azure B, a metabolite of methylene blue, is a high-potency, reversible inhibitor of monoamine oxidase". Toxicology and Applied Pharmacology. 258 (3): 403–9.