Mechanism of effect
Although the exact mechanism of action has not been determined, it appears that the irreversible, nonselective inhibition of MAO by phenelzine relieves depressive symptoms by causing an increase in the levels of serotonin, norepinephrine, and dopamine in the neuron.
Pharmacokinetics
- Peak Plasma Time: 43 min
- Metabolism: by MAO
- Onset of action: 2-4 weeks
- Duration: Therapeutic effects and interactions may continue for up to 2 weeks after discontinuing therapy
- Metabolites: phenylacetic acid & parahydroxyphenylacetic acid
- Half-Life, Elimination: 11.6 hr
- Excretion: Urine
Drug indications
BulimiaDosage
Adult
Dosage Forms
tablet
- 15mg
Depression
Initial 15 mg PO q8hr, increase not to exceed 20-30 mg q8hr
Decrease dose after maximum response (2-6 weeks) over 2-6 week period to maintain dose as low as 15 mg qDay or every other day
Monitor blood pressure
Pediatric
Safety & efficacy not established
Geriatric
Depression
Initial 15 mg PO q8hr, increase not to exceed 20-30 mg q8hr
Decrease dose after maximum response (2-6 weeks) over 2-6 week period to maintain dose as low as 15 mg qDay or every other day
Monitor blood pressure
Drug contraindications
Congestive heart failure , Pheochromocytoma , severe hypersensitivity reactionsSide effects
sleep disorder , Headache , dry mouth , dizziness , asthenia , Tremor , Weight increase , difficulty urinating , tirednessInteractions
Ergotamine-C , Oxecarbazepin , Expectorant , Brimonidine , Bupivacaine , Buspirone , Pseudoephedrine , Tetrabenazine , Tramadol , Atropine/ diphenoxylate( Lomotil® ) , Dimenhydrinate , Sibutramine , Cyproheptadine , Methyl phenidate , Modafinil , Moclobemide , fentanyl , Buprenorphine , Atomoxetine , Etomidate , Ondansetron , Bupropion , Duloxetine , Granisetron , Carbamazepine , Levodopa , Linezolid , Amoxapine , Desflurane , Tapentadol , Pethidine , safinamide , methylene blue , rasagiline , Nefazodone , Pentazocine , Almotriptan , Diethylpropion , Phenylpropanolamine , Dolasetron , Palonosetron , apraclonidine , Sufentanil , Alfentanil , lisdexamfetamine , Lorcaserin , Doxapram , Methohexital , Alphagan , Nitrous oxide , L-Tryptophan , Desvenlafaxine , Xylometazoline , Propylhexedrine , Milnacipran , acrivastine+pseudoephedrine , Doxylamine , Dexfenfluramine , chlorcyclizine + pseudoephedrine , chlorcyclizine + phenylephrine , Arformoterol , Butorphanol , Benzphetamine , Acetaminophen and benzhydrocodone , Dipipanone , Difenoxin , Cordyceps , Oxymorphone , Levomilnacipran , Guanadrel , 5-hydroxytryptophan , Ethchlorvynol , entacapone , phendimetrazine , nalbuphine , cyclopenthiazide , chlorcyclizine , NetupitantAlerts
Black Box Warnings
In short-term studies, antidepressants increased the risk of suicidal thinking and behavior in children, adolescents, and young adults (<24 yr of age) taking antidepressants for major depressive disorders and other psychiatric illnesses
This increase was not seen in patients aged >24 years; a slight decrease in suicidal thinking was seen in adults >65 years
In children and young adults, risks must be weighed against the benefits of taking antidepressants
Patients should be monitored closely for changes in behavior, clinical worsening, and suicidal tendencies; this should be done during initial 1-2 months of therapy and dosage adjustments
The patient’s family should communicate any abrupt changes in behavior to the healthcare provider
Worsening behavior and suicidal tendencies that are not part of the presenting symptoms may require discontinuation of therapy
This drug is not approved for use in pediatric patients
Cautions
Clinical worsening & suicide ideation may occur despite medication in adolescents & young adults (18-24 yo)
Hypertensive reactions may occur from consumption of foods high in tyramine or supplements containing caffeine, tyrosine, tryptophan, phenylalanine, or phenylalanine
Orthostatic hypotension may occur
Discontinue STAT at signs/symptoms of hypertensive crisis, eg, palpitations, occipital HA, N/V
Caution in patients with diabetes mellitus (monitor glucose closely), glaucoma, hepatic/renal impairment, history of seizures, thyroid dysfunction
Bipolar disorder
Hypertensive reactions may occur from consumption of foods high in tyramine or supplements containing caffeine, tyrosine, tryptophan, phenylalanine, or phenylalanine
Not first-line therapy
Discontinue 10 days before surgery
Points of recommendation
Read the Medication Guide available from your pharmacist before you start using phenelzine and each time you get a refill. If you have any questions, consult your doctor or pharmacist.
Take this medication by mouth, usually 1 to 3 times a day as directed by your doctor. This medication may be taken with or without food. Dosage is based on your medical condition and response to therapy.
To reduce your risk of side effects, your doctor may start you at a low dose and gradually increase your dose. Once your condition improves and you are better for a while, your doctor may work with you to reduce your regular dose. Follow your doctor's instructions carefully. Do not take more or less medication or take it more frequently than prescribed. Your condition will not improve any faster and your risk of side effects will increase.
Use this medication regularly in order to get the most benefit from it. To help you remember, use it at the same time(s) each day. It may take several weeks for the full benefits of this medication to be noticed. Do not stop taking this medication without consulting your doctor.
This medication may cause withdrawal reactions, especially if it has been used regularly for a long time or in high doses. In such cases, withdrawal symptoms (such as restlessness, confusion, halluinations, headache, weakness, and diarrhea) may occur if you suddenly stop using this medication. To prevent withdrawal reactions, your doctor may reduce your dose gradually. Consult your doctor or pharmacist for more details, and report any withdrawal reactions right away.
Inform your doctor if your condition persists or worsens.
Ask a Pharmacist