Drug Interaction Report

MONITOR: Coadministration with potent inhibitors of CYP450 3A4 may increase the plasma concentrations of naldemedine, which is primarily metabolized by CYP450 3A4 to nor-naldemedine and to a minor extent by UGT1A3 to naldemedine 3-G. Both metabolites have demonstrated antagonistic activity for opioid receptors, but with less potency than the parent drug. According to the product labeling, administration of naldemedine with 200 mg once daily itraconazole, a potent CYP450 3A4 and P-gp inhibitor, increased naldemedine peak plasma concentration (Cmax) by 12% and systemic exposure (AUC) by 191% compared to naldemedine administered alone. When administered with 200 mg once daily fluconazole, a moderate CYP450 3A4 inhibitor, naldemedine Cmax and AUC increased by 38% and 90%, respectively. When administered with a single 600 mg dose of cyclosporine, a potent P-gp but weak CYP450 3A4 inhibitor, naldemedine Cmax and AUC increased by 45% and 78%, respectively. Increased exposure to naldemedine may precipitate opioid withdrawal symptoms such as hyperhidrosis, lacrimation, rhinorrhea, chills, diarrhea, abdominal pain, anxiety, insomnia, irritability, restlessness, and yawning.

MANAGEMENT: Caution is advised during concomitant use of naldemedine with potent inhibitors of CYP450 3A4. Patients should be closely monitored for potential opioid withdrawal symptoms as well as other adverse effects of naldemedine.

GENERALLY AVOID: Alcohol may potentiate some of the pharmacologic effects of CNS-active agents. Use in combination may result in additive central nervous system depression and/or impairment of judgment, thinking, and psychomotor skills.

MANAGEMENT: Patients receiving CNS-active agents should be warned of this interaction and advised to avoid or limit consumption of alcohol. Ambulatory patients should be counseled to avoid hazardous activities requiring complete mental alertness and motor coordination until they know how these agents affect them, and to notify their physician if they experience excessive or prolonged CNS effects that interfere with their normal activities.

GENERALLY AVOID: Grapefruit juice may increase the plasma concentrations of naldemedine. The proposed mechanism is inhibition of CYP450 3A4-mediated first-pass metabolism in the gut wall by certain compounds present in grapefruit. In pharmacokinetic studies, naldemedine systemic exposure (AUC) was increased approximately 90% by the moderate CYP450 3A4 inhibitor fluconazole and nearly 200% by the potent inhibitor itraconazole. The interaction has not been studied with grapefruit juice. 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. Increased exposure to naldemedine may precipitate opioid withdrawal symptoms such as hyperhidrosis, lacrimation, rhinorrhea, chills, diarrhea, abdominal pain, anxiety, insomnia, irritability, restlessness, and yawning.

Food does not significantly affect the overall bioavailability of naldemedine. When administered with a high-fat meal, the rate of naldemedine absorption was decreased, but not the extent. Specifically, naldemedine peak plasma concentration (Cmax) was decreased by approximately 35% and time to achieve Cmax was delayed from 0.75 hours in the fasted state to 2.5 hours in the fed state, while naldemedine AUC was not significantly changed.

MANAGEMENT: Naldemedine may be taken with or without food. Patients should avoid consumption of grapefruit and grapefruit juice during treatment with naldemedine.