Monoamine oxidase inhibitor toxicity: Difference between revisions
ClaireLewis (talk | contribs) No edit summary |
|||
Line 1: | Line 1: | ||
==Background== | ==Background== | ||
*MonoAmine Oxidase Inhibitors (MAOI) | *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 | ||
===Toxicity Mechanisms=== | ===Toxicity Mechanisms=== | ||
Line 21: | Line 25: | ||
==Clinical Features== | ==Clinical Features== | ||
*Similar to hyperadrenergic state (tachycardia, hypertension, hyperthermia) | *Similar to hyperadrenergic state ([[tachycardia]], [[hypertension]], [[hyperthermia]]) | ||
*Severe toxicity accompanied by [[coma]], [[seizure]], [[bradycardia]], [[hypotension]], worsening [[hyperthermia]], [[rhabdomyolysis]] | *Severe toxicity accompanied by [[coma]], [[seizure]], [[bradycardia]], [[hypotension]], worsening [[hyperthermia]], [[rhabdomyolysis]] | ||
Line 28: | Line 32: | ||
**[[Amphetamines]] | **[[Amphetamines]] | ||
**[[Antimuscarinics]] | **[[Antimuscarinics]] | ||
**Methylxanthine toxicity (theophylline, caffeine) | **Methylxanthine toxicity ([[theophylline toxicity|theophylline]], [[caffeine toxicity|caffeine]]) | ||
**St. John's Wort | **St. John's Wort | ||
*Withdrawal states | *Withdrawal states | ||
**[[Ethanol withdrawal|Ethanol]] | **[[Ethanol withdrawal|Ethanol]] | ||
**[[Benzodiazepine withdrawal]] | **[[Benzodiazepine withdrawal]] | ||
**Clonidine | **[[Clonidine]] | ||
**Beta-blockers | **[[Beta-blockers]] | ||
*Medical conditions | *Medical conditions | ||
**[[Heat stroke]] | **[[Heat stroke]] | ||
Line 50: | Line 54: | ||
==Evaluation== | ==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 | *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 | *consider ECG and chemistry panel in MAOI overdose patients who are obtunded | ||
Line 60: | Line 64: | ||
#Supportive care | #Supportive care | ||
#*Hypertension | #*Hypertension | ||
#**Treat only with short-acting agents: may develop precipitous hypotension | #**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 | #**[[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 | #**[[Nitroprusside]]: 1mcg/kg/min and titrate up | ||
#*Hypotension: intravenous fluid +/- norepinephrine | #*Hypotension: intravenous fluid +/- [[norepinephrine]] | ||
#*CNS excitation and [[Seizures]]: benzodiazepines are 1st line | #*CNS excitation and [[Seizures]]: [[benzodiazepines]] are 1st line | ||
#*Hyperthermia | #*Hyperthermia | ||
#**Routine cooling measures | #**Routine cooling measures | ||
#**Consider paralysis if patient has persistent muscle rigidity | #**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 (risk of delayed hyperadrenergic symptoms) | *Admit all patients for 24 hour observation to monitored setting (risk of delayed hyperadrenergic symptoms) | ||
==See Also== | ==See Also== |
Revision as of 14:11, 1 September 2019
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
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.