Drug Interaction Report

GENERALLY AVOID: Grapefruit and grapefruit juice may increase the plasma concentrations of lumateperone. The proposed mechanism is inhibition of CYP450 3A4-mediated first-pass metabolism in the gut wall by certain compounds present in grapefruit. Inhibition of hepatic CYP450 3A4 may also contribute. The interaction has not been studied with grapefruit but has been reported for other CYP450 3A4 inhibitors. In a drug interaction study, the strong CYP450 3A4 inhibitor itraconazole increased lumateperone peak plasma concentration (Cmax) and systemic exposure (AUC) approximately 3.5- and 4-fold, respectively, while diltiazem (a moderate CYP450 3A4 inhibitor) increased lumateperone Cmax and AUC approximately 2- and 2.5-fold, respectively. In general, the effect of grapefruit juice is concentration-, dose- and preparation-dependent, and can vary widely among brands. Certain preparations of grapefruit juice (e.g., high dose, double strength) have sometimes demonstrated potent inhibition of CYP450 3A4, while other preparations (e.g., low dose, single strength) have typically demonstrated moderate inhibition.

When administered with a high-fat meal, lumateperone Cmax decreased by 33% while its AUC increased by 9% and its median time to peak plasma concentration (Tmax) was delayed by about 1 hour.

MANAGEMENT: Lumateperone should be administered with food. Coadministration of grapefruit or grapefruit juice with lumateperone should be avoided.

MONITOR: Two cases have been reported in which patients on sulfamethoxazole-trimethoprim therapy, after consuming beer, reported flushing, heart palpitations, dyspnea, headache, and nausea (disulfiram - alcohol type reactions). First-generation sulfonylureas have been reported to cause facial flushing when administered with alcohol by inhibiting acetaldehyde dehydrogenase and subsequently causing acetaldehyde accumulation. Since sulfamethoxazole is chemically related to first-generation sulfonylureas, a disulfiram-like reaction with products containing sulfamethoxazole is theoretically possible. However, pharmacokinetic/pharmacodynamic data are lacking and in addition, the two reported cases cannot be clearly attributed to the concomitant use of sulfamethoxazole-trimethoprim and alcohol.

MANAGEMENT: Patients should be alerted to the potential for this interaction and although the risk for this interaction is minimal, caution is recommended while taking sulfamethoxazole-trimethoprim concomitantly with alcohol.