Interactions between rifampin and Inh (isoniazid)
rifampin and isoniazid (Major Drug-Drug)
MONITOR CLOSELY: The risk of hepatotoxicity is greater when rifampin and isoniazid are given concomitantly than when either drug is given alone. Rifampin appears to alter the metabolism of isoniazid and increase the amount of toxic metabolites. Theoretically, a similar reaction may occur with rifabutin and isoniazid. Patients who are elderly, have hepatic impairment, are slow acetylators of isoniazid, drink alcohol daily, are female, or are taking other strong CYP450-inducing agents may be at greater risk of hepatotoxicity.
MANAGEMENT: Close monthly monitoring for clinical or laboratory evidence of altered hepatic function is recommended. Patients should be advised to promptly report early symptoms of hepatitis such as fatigue, weakness, malaise, anorexia, nausea, or vomiting. Discontinuation of either or both drugs may be necessary.
