Drug Interactions between Cerdelga and Tecfidera

GENERALLY AVOID: Grapefruit juice may significantly increase the systemic exposure to eliglustat. The proposed mechanism is inhibition of CYP450 3A4-mediated first-pass metabolism in the gut wall by certain compounds present in grapefruit. Because eliglustat is predicted to cause prolongation of the PR, QTc, and QRS cardiac intervals at substantially elevated plasma concentrations, consumption of grapefruit juice during treatment may increase the risk of bradycardia, atrioventricular block, cardiac arrest, and serious ventricular arrhythmias such as torsade de pointes.

MANAGEMENT: Patients treated with eliglustat should avoid consumption of grapefruit and grapefruit juice.

Food does not significantly affect the oral bioavailability of dimethyl fumarate. Administration of dimethyl fumarate with a high-fat, high-calorie meal did not affect the systemic exposure (AUC) to its active metabolite, monomethyl fumarate (MMF), but decreased its peak plasma concentration (Cmax) by 40% and prolonged the time to reach peak concentration (Tmax) from 2.0 hours to 5.5 hours. In the study, the incidence of flushing was reduced by approximately 25% in the fed state. Dimethyl fumarate may be taken with or without food; however, taking it with food may help reduce flushing.