Drug Interactions between isoniazid and procarbazine

Consumer information for this interaction is not currently available.

GENERALLY AVOID: Coadministration of isoniazid (INH) with monoamine oxidase inhibitors (MAOIs) or drugs that possess MAOI activity (e.g., furazolidone, linezolid, methylene blue, procarbazine) may increase the risk of hypertensive crises and/or serotonin syndrome due to elevated levels of neurotransmitters (e.g., norepinephrine, serotonin, dopamine). Isoniazid is considered a weak inhibitor of monoamine oxidase (MAO), the enzyme primarily responsible for breaking down norepinephrine, serotonin, and dopamine. Combining INH with drugs that also inhibit the breakdown of some or all these neurotransmitters may have additive effects. According to isoniazid product labeling, a known interaction exists between isoniazid and tyramine-rich foods. Tyramine is a potent releaser of norepinephrine and is normally broken down by MAO; however, when present in high concentrations (e.g., when an MAOI is present) increased adrenergic tone and symptoms of tachycardia, hyperthermia, myoclonus, hypertension, and agitation can occur. On the other hand, some authors suggest that the interaction of isoniazid with tyramine-rich foods is more likely related to a histamine reaction, rather than the inhibition of MAO by isoniazid. Current available data involving isoniazid with MAOIs or drugs that possess MAOI activity are limited to case reports and speculation, consensus on the safety of concomitant use of isoniazid with these drugs is lacking.

MANAGEMENT: Until more information is available, coadministration of isoniazid with monoamine oxidase inhibitors (MAOIs) or drugs that possess MAOI activity (e.g., furazolidone, linezolid, methylene blue, procarbazine) should generally be avoided. If coadministration with MAOIs is required, patients should be advised to promptly seek medical attention if they experience signs and symptoms of a hypertensive crisis and/or serotonin syndrome (including but not limited to severe headache, visual disturbances, difficulty thinking, chest pain, confusion, hallucinations, tachycardia, hyperthermia, diaphoresis, shivering, blood pressure lability, neuromuscular abnormalities and/or unexplained gastrointestinal symptoms).