Drug Interaction Report

GENERALLY AVOID: Coadministration with weak inhibitors of CYP450 3A4 may increase the plasma concentrations of eliglustat, which is primarily metabolized by CYP450 2D6 and, to a lesser extent, CYP450 3A4. Eliglustat at substantially elevated plasma concentrations is predicted to cause prolongation of the PR, QTc and QRS cardiac intervals, which may increase the risk of bradycardia, atrioventricular block, cardiac arrest, and serious ventricular arrhythmias such as torsade de pointes. Simulations using physiologically-based pharmacokinetic (PBPK) models suggest that the potent CYP450 3A4 inhibitor ketoconazole may increase eliglustat systemic exposure (AUC) by 4.4-, 5.4- and 6.2-fold in CYP450 2D6 extensive metabolizers (EMs), intermediate metabolizers (IMs) and poor metabolizers (PMs), respectively, while the moderate CYP450 3A4 inhibitor fluconazole may increase eliglustat AUC by 3.2-, 2.9- and 3.0-fold, respectively. No data are available for use with other, less potent inhibitors.

MANAGEMENT: Concomitant use of eliglustat with weak CYP450 3A4 inhibitors such as chloramphenicol, cyclosporine, danazol, dasatinib, ethinyl estradiol, fluvoxamine, goldenseal, isoniazid, ivacaftor, lapatinib, lomitapide, nifedipine, nilotinib, palbociclib, pazopanib, suvorexant, ticagrelor, and zafirlukast is not recommended in CYP450 2D6 poor metabolizers. No dosage adjustment for eliglustat is necessary when used with weak CYP450 3A4 inhibitors in extensive or intermediate metabolizers.

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.

H2 antagonists may reduce the clearance of nicotine. Cimetidine, 600 mg given twice a day for two days, reduced clearance of an intravenous nicotine dose by 30%. Ranitidine, 300 mg given twice a day for two days, reduced clearance by 10%. The clinical significance of this interaction is not known. Patients should be monitored for increased nicotine effects when using the patches or gum for smoking cessation and dosage adjustments should be made as appropriate.