Drug Interaction Report

MONITOR: Because telbivudine is primarily eliminated by renal excretion, coadministration with drugs that affect renal function may alter the plasma concentrations of telbivudine and/or the coadministered drug.

MANAGEMENT: Caution is advised if telbivudine is prescribed in combination 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). Renal function should be evaluated prior to and during therapy with telbivudine. Adjustment of dosing interval is required in patients with renal insufficiency (creatinine clearance below 50 mL/min) at baseline or during treatment in accordance with the manufacturer's product labeling.

GENERALLY AVOID: Coadministration of temsirolimus with grapefruit juice may increase the plasma concentrations of sirolimus, a major active metabolite of temsirolimus and known substrate of CYP450 3A4. The proposed mechanism is inhibition of CYP450 3A4-mediated metabolism by certain compounds present in grapefruits.

MANAGEMENT: Patients treated with temsirolimus should preferably avoid the consumption of grapefruit or grapefruit juice.