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 (125mg/80-mg/80-mg) and can increase plasma concentrations of concomitant drugs that are substrates for CYP3A4. Aprepitant acts as a weak inhibitor when administered as a single 40-mg dose and has not been shown to alter the plasma concentrations of concomitant drugs that are primarily metabolized through CYP3A4. Some substrates of CYP3A4 are contraindicated with aprepitant. Dosage adjustment of some CYP3A4 and CYP2C9 substrates may be warranted, as shown in Table 10.

Table 10: Effects of Aprepitant on the Pharmacokinetics of Other Drugs CYP3A4 Substrates Pimozide Clinical Impact Increased pimozide exposure Intervention Aprepitant 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 3-day aprepitant regimen 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 Single 40 mg dose of aprepitant No dosage adjustment of the benzodiazepine needed Dexamethasone Clinical Impact Increased dexamethasone exposure. Intervention 3-day aprepitant regimen Reduce the dose of oral dexamethasone by approximately 50%. Single 40 mg dose of aprepitant No dosage adjustment of oral dexamethasone needed Methylprednisolone Clinical Impact Increased methylprednisolone exposure. Intervention 3-day aprepitant regimen Reduce the dose of intravenous methylprednisolone by approximately 25% Reduce the dose of oral methylprednisolone by approximately 50% Single 40 mg dose of aprepitant No dosage adjustment of methylprednisolone needed 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 aprepitant. Intervention Effective alternative or back-up methods of contraception (such as condoms and spermicides) should be used during treatment with aprepitant and for 1 month following the last dose of aprepitant. 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 aprepitant regimen with each chemotherapy cycle, or following administration of a single 40-mg dose of aprepitant. 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 aprepitant with drugs that are inhibitors or inducers of CYP3A4 may result in increased or decreased plasma concentrations of aprepitant, respectively, as shown in Table 11.

Table 11: 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 aprepitant. Intervention Avoid concomitant use of aprepitant 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 aprepitant. Intervention Avoid concomitant use of aprepitant Examples rifampin, carbamazepine, phenytoin

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 (125mg/80-mg/80-mg) and can increase plasma concentrations of concomitant drugs that are substrates for CYP3A4. Aprepitant acts as a weak inhibitor when administered as a single 40-mg dose and has not been shown to alter the plasma concentrations of concomitant drugs that are primarily metabolized through CYP3A4. Some substrates of CYP3A4 are contraindicated with aprepitant. Dosage adjustment of some CYP3A4 and CYP2C9 substrates may be warranted, as shown in Table 10.

Table 10: Effects of Aprepitant on the Pharmacokinetics of Other Drugs CYP3A4 Substrates Pimozide Clinical Impact Increased pimozide exposure Intervention Aprepitant 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 3-day aprepitant regimen 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 Single 40 mg dose of aprepitant No dosage adjustment of the benzodiazepine needed Dexamethasone Clinical Impact Increased dexamethasone exposure. Intervention 3-day aprepitant regimen Reduce the dose of oral dexamethasone by approximately 50%. Single 40 mg dose of aprepitant No dosage adjustment of oral dexamethasone needed Methylprednisolone Clinical Impact Increased methylprednisolone exposure. Intervention 3-day aprepitant regimen Reduce the dose of intravenous methylprednisolone by approximately 25% Reduce the dose of oral methylprednisolone by approximately 50% Single 40 mg dose of aprepitant No dosage adjustment of methylprednisolone needed 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 aprepitant. Intervention Effective alternative or back-up methods of contraception (such as condoms and spermicides) should be used during treatment with aprepitant and for 1 month following the last dose of aprepitant. 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 aprepitant regimen with each chemotherapy cycle, or following administration of a single 40-mg dose of aprepitant. 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 aprepitant with drugs that are inhibitors or inducers of CYP3A4 may result in increased or decreased plasma concentrations of aprepitant, respectively, as shown in Table 11.

Table 11: 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 aprepitant. Intervention Avoid concomitant use of aprepitant 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 aprepitant. Intervention Avoid concomitant use of aprepitant Examples rifampin, carbamazepine, phenytoin