DRUG INTERACTIONS
Warfarin or Coumarin Derivatives
Prolongation of PT and elevation of INR were observed in a patient receiving ISTODAX concomitantly with warfarin. Although the interaction potential between ISTODAX and warfarin has not been formally studied, monitor PT and INR more frequently in patients concurrently receiving ISTODAX and warfarin [see Clinical Pharmacology].
Drugs That Inhibit Cytochrome P450 3A4 Enzymes
Romidepsin is metabolized by CYP3A4. Strong CYP3A4 inhibitors increase concentrations of romidepsin. In a pharmacokinetic drug interaction trial the strong CYP3A4 inhibitor ketoconazole increased romidepsin (AUC0-∞) by approximately 25% [see Clinical Pharmacology].
Monitor for toxicity related to increased romidepsin exposure and follow the dose modifications for toxicity [see Dosage and Administration] when romidepsin is initially co-administered with strong CYP3A4 inhibitors (e.g., ketoconazole, itraconazole, clarithromycin, atazanavir, indinavir, nefazodone, nelfinavir, ritonavir, saquinavir, telithromycin, voriconazole).
Drugs That Induce Cytochrome P450 3A4 Enzymes
Avoid co-administration of ISTODAX with rifampin.
In a pharmacokinetic drug interaction trial with co-administered rifampin (a strong CYP3A4 inducer), romidepsin exposure was increased by approximately 80% and 60% for AUC0-∞ and Cmax, respectively [see Clinical Pharmacology]. Typically, co-administration of CYP3A4 inducers decrease concentrations of drugs metabolized by CYP3A4. The increase in exposure seen after co-administration with rifampin is likely due to rifampin’s inhibition of an undetermined hepatic uptake process that is predominantly responsible for the disposition of ISTODAX.
It is unknown if other potent CYP3A4 inducers (e.g., dexamethasone, carbamazepine, phenytoin, rifabutin, rifapentine, phenobarbital, St. John’s Wort) would alter the exposure of ISTODAX. Therefore, the use of other potent CYP3A4 inducers should be avoided when possible.
Drugs That Inhibit Drug Transport Systems
Romidepsin is a substrate of the efflux transporter P-glycoprotein (P-gp, ABCB1). If ISTODAX is administered with drugs that inhibit P-gp, increased concentrations of romidepsin are likely, and caution should be exercised.
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