Drug Interactions between Champix and ranolazine

GENERALLY AVOID: Grapefruit and grapefruit juice may significantly increase the plasma concentrations of orally administered ranolazine. The proposed mechanism is inhibition of CYP450 3A4-mediated first-pass metabolism in the gut wall by certain compounds present in grapefruit. Because ranolazine prolongs QT interval in a dose-dependent manner, high plasma levels of ranolazine may increase the risk of ventricular arrhythmias such as ventricular tachycardia, ventricular fibrillation, and torsade de pointes.

MANAGEMENT: Patients treated with ranolazine should avoid consumption of grapefruit juice and other grapefruit products if possible. Otherwise, the dosage of ranolazine should be limited to 500 mg twice a day.

GENERALLY AVOID: Varenicline may enhance the effects of alcohol as well as alter the way an individual reacts to alcohol. During postmarketing use, some patients have reported experiencing increased intoxicating effects of alcohol while taking varenicline. In addition, some reported cases of neuropsychiatric events, including unusual and sometimes aggressive behavior directed toward oneself or others, may have been worsened by concomitant use of alcohol. These events were often accompanied by amnesia.

MANAGEMENT: Patients should be advised to limit their consumption of alcohol until they know whether varenicline affects their tolerance for alcohol, and to exercise caution driving or operating machinery until they know how quitting smoking and/or varenicline may affect them. Patients should immediately stop taking varenicline and contact their physician if they develop agitation, hostility, aggressive behavior, depressed mood, or changes in behavior or thinking that are not typical for them, or if they develop suicidal ideation or behavior.