Drug Interaction Report

MONITOR: Coadministration with drugs that are nephrotoxic may delay and/or decrease the clearance of pemetrexed, which is primarily eliminated unchanged by the kidney via glomerular filtration and active tubular secretion.

MANAGEMENT: Caution is advised if pemetrexed is used in patients who have recently received or are receiving treatment with potentially nephrotoxic drugs (e.g., aminoglycosides; polypeptide, glycopeptide, and polymyxin antibiotics; amphotericin B; adefovir; cidofovir; tenofovir; foscarnet; cisplatin; deferasirox; gallium nitrate; lithium; mesalamine; certain immunosuppressants; intravenous bisphosphonates; intravenous pentamidine; high intravenous dosages of methotrexate; high dosages and/or chronic use of nonsteroidal anti-inflammatory agents). The potential for increased toxicity of pemetrexed such as bone marrow suppression should be considered. Renal function should be closely monitored during therapy. Pemetrexed should not be administered to patients whose creatinine clearance is below 45 mL/min.

Food enhances the oral absorption and bioavailability of tenofovir, the active entity of tenofovir disoproxil fumarate. According to the product labeling, administration of the drug following a high-fat meal increased the mean peak plasma concentration (Cmax) and area under the concentration-time curve (AUC) of tenofovir by approximately 14% and 40%, respectively, compared to administration in the fasting state. However, administration with a light meal did not significantly affect the pharmacokinetics of tenofovir compared to administration in the fasting state. Food delays the time to reach tenofovir Cmax by approximately 1 hour. Tenofovir disoproxil fumarate may be administered without regard to meals.