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Pronunciation: eye-so-car-BOX-ah-zid
Class: MAOI

Trade Names

- Tablets 10 mg


Blocks activity of enzyme MAO, thereby increasing monoamine (eg, epinephrine, norepinephrine, serotonin) concentrations in CNS.

Slideshow: Depression, the Risk of Suicide, and Treatment Options

Indications and Usage

Treatment of depression.


Patients with known hypersensitivity to any component of the product; coadministration of MAOIs, dibenzazepine derivatives, sympathomimetics (including amphetamines), some CNS depressants (including narcotics and alcohol), antihypertensives, diuretic, antihistaminic, anti-Parkinson drugs; sedative or anesthetic drugs, bupropion, buspirone, dextromethorphan, serotonin reuptake inhibitors (eg, fluoxetine); cheese or other foods high in tyramine content, excessive quantities of caffeine; patients with confirmed or suspected cerebrovascular defect, CV disease, hypertension, or history of headache, pheochromocytoma, history of liver disease, abnormal LFTs, severe renal function impairment. Allow a medicine-free interval of at least 1 wk when transferring a patient to isocarboxazid from another MAOI or a dibenzazepine-related agent, then initiate therapy using ½ the normal starting dosage for at least the first week; similarly, allow 1 wk between discontinuing isocarboxazid and another MAOI or dibenzazepine-related agent, or readministration of isocarboxazid.

Dosage and Administration

Adults and Children 16 yr of age and older

PO Start with 10 mg twice daily. Dosage may be increased by 10 mg increments every 2 to 4 days to achieve a dosage of 40 mg by the end of the first week. Dosage can then be increased up to 20 mg/wk. Daily dosages should be divided into 2 to 4 doses (max, 60 mg/day).

General Advice

Administer without regard to meals but give with food if GI upset occurs.


Store tablets at controlled room temperature (59° to 86°F).

Drug Interactions

Amine-containing Foods

May cause severe hypertension or hemorrhagic strokes.

Anorexiants (eg, amphetamines)

May cause exaggerated pharmacologic effects (eg, severe headaches, hypertension, hyperpyrexia) of anorexiant.

Antihypertensive agents (eg, thiazide diuretics)

Potentiative hypotensive effects.

Antiparkinson agents (eg, levodopa)

May cause hypertensive reactions.

Bupropion, buspirone, carbamazepine, CNS stimulants, cyclobenzaprine, guanethidine, maprotiline, serotonin reuptake inhibitors (fluoxetine), sympathomimetics, tricyclic antidepressants, tyramine

May lead to potentially fatal reactions, including seizures and hypertensive crisis; mental status changes, hyperthermia.

CNS depressants

May enhance CNS effects.


Use has been associated with severe reactions (eg, hyperpyrexia, hypotension, death, psychosis, bizarre behavior).


May cause convulsions and death.

Insulin, sulfonylureas (eg, chlorpropamide)

May enhance hypoglycemic action.


May lead to severe reactions, including hypotension, convulsions, respiratory depression, and vascular collapse.

Selective 5-HT 1 receptor agonists (eg, sumatriptan)

May increase the risk of cardiac toxicity (eg, coronary artery vasospasm).

Laboratory Test Interactions

None well documented.

Adverse Reactions


Orthostatic hypotension (4%); palpitations (2%).


Dizziness (29%); headache (15%); sleep disturbance (5%); drowsiness, insomnia, tremor (4%); anxiety, forgetfulness, hyperactivity, lethargy, sedation, myoclonic jerks, paresthesia (2%).


Sweating (2%).


Nausea (10%); dry mouth (9%); constipation (7%); diarrhea (2%).


Urinary hesitancy (4%); urinary frequency, impotence (2%).


Chills, syncope, heavy feeling (2%).





Use not recommended.


Safety and efficacy not established in children younger than 16 yr of age.


Use with caution.

Renal Function

Use with caution.

Anginal pain

May be suppressed, masking a warning of MI.

Co-existing symptoms of depression

Symptoms, such as anxiety and agitation, may be aggravated.


May lower seizure threshold.

Hyperactive or agitated patients

Use with caution.


Orthostatic hypotension is a significant adverse reaction and may lead to falling and changes in heart rate.


Strict supervision may be necessary in patients at risk.



Tachycardia, hypotension, coma, convulsions, respiratory depression, sluggish reflexes, pyrexia, diaphoresis.

Patient Information

  • Review foods, beverages, and medications that must be avoided during treatment and for at least 2 wk following discontinuation of therapy.
  • Advise patient that medication will be started at a low dose and then increased as tolerated until max benefit is obtained.
  • Inform patient that it may take 3 to 6 wk for symptoms to improve and to continue with the prescribed therapy once improvement has been noted.
  • Advise patient to take prescribed dose without regard to meals but to take with food if GI upset occurs.
  • Advise patient that if a dose is missed, to skip that dose and take the next dose at the regularly scheduled time. Caution patient never to take 2 doses at the same time.
  • Caution patient not to change the dose or stop taking unless advised by health care provider.
  • Advise patient to take frequent sips of water, suck on ice chips or sugarless hard candy, or chew sugarless gum if dry mouth occurs.
  • Advise patient to avoid alcoholic beverages and tryptophan while taking isocarboxazid.
  • Caution patient to avoid sudden position changes to prevent orthostatic hypotension (dizziness or faintness when arising suddenly from a sitting or lying position). Advise patient to sit or lie down if dizziness or faintness occurs and to notify health care provider if this persists or worsens.
  • Instruct diabetic patient to monitor blood glucose more frequently when drug is started or dose is changed and to inform health care provider of significant changes in readings.
  • Advise patient that drug may cause drowsiness or blurred vision and to use caution while driving or performing other tasks requiring mental alertness until tolerance is determined.
  • Instruct patient to discontinue use and notify health care provider immediately if any of the following occur: pounding in the chest (palpitations), severe headache, unexplained rapid heartbeat, sweating, dizziness, neck stiffness, feeling of constriction in throat or chest, persistent nausea or vomiting, any other unusual symptom.

Copyright © 2009 Wolters Kluwer Health.