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Monoamine Oxidase Inhibitor
Aka: Monoamine Oxidase Inhibitor, MAO inhibitor, Phenelzine, Nardil, Tranylcypromine, Parnate
- Indications: Comorbid Depression
- Anxiety Disorder
- Atypical Depression
- Refractory Depression
- Bulimia
- Social Phobia
- Mechanism
- Inhibits monoamine oxidase
- Monoamine Oxidase is enzyme that breaks down biogenic amines (e.g. Norepinephrine, Serotonin, Dopamine)
- Type A Monoamine Oxidase affects Gastrointestinal System
- Type B Monoamine Oxidase affects Central Nervous System
- Older MAO inhibitors are nonspecific and affect both Type A and B (e.g. trancypromine, Phenelzine)
- Selegiline is specific for Type B and is used in Parkinsonism
- Increases synaptic concentration of monoamines
- Serotonin
- Norepinephrine
- Precautions
- Tyramine-free diet must be followed
- Continue for two weeks after stopping medication
- See Tyramine Containing Foods
- Stop 2 weeks before starting another Antidepressant
- Taper Nardil slowly when stopping
- See Antidepressant Withdrawal
- Reduce dose by 15 mg/day every 2 weeks (or 10%/week)
- Preparations: Hydrazine
- Isocarboxazid (Marplan): No longer manufactured in U.S.
- Dosing: 10 mg PO bid
- Maximum: 60 mg per day
- Phenelzine (Nardil)
- Dosing: 15 mg PO tid
- Maximum: 90 mg per day
- Preparations Non-hydrazine
- Tranylcypromine (Parnate)
- Dosing: 10-40 mg/day in divided doses
- Maximum: 60 mg per day
- Parkinsonian agents
- Selegiline (Eldepryl)
- Preparations: Other agents with MAO inhibitor Activity
- Linezolid
- St John's Wort
- Contains Hypericin and Hyperforin (weak Type A and B MAO inhibitors)
- Complications
- Hypertensive Crisis (life-threatening)
- Occurs if tyramine or Sympathomimetic exposure
- Treat with phentolamine (alpha-adrenergic antagonist)
- Hypotension to cardiovascular collapse (occurs with Overdose)
- Treat with Intravenous Fluids and direct acting Vasopressors (e.g. Norepinephrine)
- Serotonin Syndrome
- Occurs with concurrent use of other Serotoninergic drug, or in Overdose
-
Drug Interactions (Do not use with these medications)
- Tyramine Containing Foods
- Sympathomimetics (Ephedra, Ephedrine)
- Serotoninergic medications
- Selective Serotonin Reuptake Inhibitors (SSRI)
- Adverse Effects
- Anti-Histaminergic effects
- Dizziness
- Sedation
- Orthostatic Hypotension
- Weight gain
- Dopaminergic effects
- Insomnia
- Myoclonal jerks
- Serotoninergic Effects
- Sexual Dysfunction
- Headache
- Anticholinergic Toxicity
- Dry Mouth
- Constipation
- Blurred Vision
- Urinary hesitancy
- Nausea
- Memory Dysfunction
- Other Effects
- Peripheral Edema
- Weakness
- References
- Nordt and Shoenberger in Herbert (2019) EM:Rap 19(3): 8-9