Aprepitantinteractions

See Full Prescribing Information for a list of clinically significant drug interactions.

7.1 Effect of

Aprepitant on the Pharmacokinetics of Other Drugs Aprepitant is a substrate, a weak-to-moderate (dose-dependent) inhibitor, and an inducer of CYP3A4. Aprepitant is also an inducer of CYP2C9. Aprepitant acts as a moderate inhibitor of CYP3A4 when administered as a 3-day regimen (125-mg/80-mg/80-mg) and can increase plasma concentrations of concomitant drugs that are substrates for CYP3A4. Some substrates of CYP3A4 are contraindicated with EMEND. Dosage adjustment of some CYP3A4 and CYP2C9 substrates may be warranted, as shown in Table 8.

Table 8: Effects of Aprepitant on the Pharmacokinetics of Other Drugs CYP3A4 Substrates Pimozide Clinical Impact Increased pimozide exposure. Intervention EMEND is contraindicated. Benzodiazepines Clinical Impact Increased exposure to midazolam or other benzodiazepines metabolized via CYP3A4 (alprazolam, triazolam) may increase the risk of adverse reactions. Intervention Monitor for benzodiazepine-related adverse reactions. Depending on the clinical situation (e.g., elderly patients) and degree of monitoring available, reduce the dose of intravenous midazolam Dexamethasone Clinical Impact Increased dexamethasone exposure. Intervention Reduce the dose of oral dexamethasone by approximately 50%. Methylprednisolone Clinical Impact Increased methylprednisolone exposure. Intervention Reduce the dose of intravenous methylprednisolone by approximately 25% Reduce the dose of oral methylprednisolone by approximately 50% Chemotherapeutic agents that are metabolized by CYP3A4 Clinical Impact Increased exposure of the chemotherapeutic agent may increase the risk of adverse reactions. Intervention Vinblastine, vincristine, or ifosfamide or other chemotherapeutic agents Monitor for chemotherapeutic-related adverse reactions. Etoposide, vinorelbine, paclitaxel, and docetaxel No dosage adjustment needed. Hormonal Contraceptives Clinical Impact Decreased hormonal exposure during administration of and for 28 days after administration of the last dose of EMEND. Intervention Effective alternative or back-up methods of contraception (such as condoms and spermicides) should be used during treatment with EMEND and for 1 month following the last dose of EMEND. Examples birth control pills, skin patches, implants, and certain IUDs CYP2C9 Substrates Warfarin Clinical Impact Decreased warfarin exposure and decreased prothrombin time (INR). Intervention In patients on chronic warfarin therapy, monitor the prothrombin time (INR) in the 2-week period, particularly at 7 to 10 days, following initiation of the 3-day EMEND regimen with each chemotherapy cycle. Other 5-HT 3 Antagonists Clinical Impact No change in the exposure of the 5-HT 3 antagonist. Intervention No dosage adjustment needed Examples ondansetron, granisetron, dolasetron

7.2 Effect of

Other Drugs on the Pharmacokinetics of Aprepitant Aprepitant is a CYP3A4 substrate. Co-administration of EMEND with drugs that are inhibitors or inducers of CYP3A4 may result in increased or decreased plasma concentrations of aprepitant, respectively, as shown in Table 9.

Table 9: Effects of Other Drugs on Pharmacokinetics of Aprepitant Moderate to Strong CYP3A4 Inhibitors Clinical Impact Significantly increased exposure of aprepitant may increase the risk of adverse reactions associated with EMEND. Intervention Avoid concomitant use of EMEND.

Examples Moderate inhibitor: diltiazem Strong inhibitors: ketoconazole, itraconazole, nefazodone, troleandomycin, clarithromycin, ritonavir, nelfinavir Strong CYP3A4 Inducers Clinical Impact Substantially decreased exposure of aprepitant in patients chronically taking a strong CYP3A4 inducer may decrease the efficacy of EMEND. Intervention Avoid concomitant use of EMEND. Examples rifampin, carbamazepine, phenytoin