Drug Interactions between adefovir and celecoxib / tramadol

MONITOR CLOSELY: Coadministration of adefovir dipivoxil with other nephrotoxic agents may increase the risk and severity of renal impairment due to additive effects on the kidney. Additionally, renal impairment secondary to the use of these agents may reduce the clearance of adefovir, which is primarily eliminated by renal excretion. The use of adefovir dipivoxil has been associated with dose-related nephrotoxicity characterized by a delayed onset of gradual increases in serum creatinine and decreases in serum phosphorus. Generally, the risk is low in patients with adequate renal function receiving 10 mg/day but increases with increasing dosage and in patients with underlying renal impairment.

MANAGEMENT: Caution is advised if adefovir dipivoxil must be used in patients who have recently received or are receiving treatment with other potentially nephrotoxic agents (e.g., aminoglycosides; polypeptide, glycopeptide, and polymyxin antibiotics; amphotericin B; 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 adefovir dipivoxil. Patients with renal insufficiency at baseline or during treatment may require dosage adjustment in accordance with the manufacturer's product labeling.

MONITOR: Coadministration with celecoxib may increase the plasma concentrations of drugs that are substrates of the CYP450 2D6 isoenzyme. The mechanism is decreased clearance due to inhibition of CYP450 2D6 activity by celecoxib.

MANAGEMENT: Caution is advised if celecoxib must be used concurrently with medications that undergo metabolism by CYP450 2D6, particularly those with a narrow therapeutic range. Dosage adjustments as well as clinical and laboratory monitoring may be appropriate for some drugs whenever celecoxib is added to or withdrawn from therapy.