Foscarnet and Renal dysfunction

Foscarnet is eliminated primarily by the kidney. Patients with renal impairment may be at greater risk for dose-limiting nephrotoxicity and other adverse effects of foscarnet due to decreased drug clearance. Renal function should be closely monitored in all patients receiving therapy with foscarnet, and the dosage adjusted based on serum creatinine. Hydration is recommended to reduce the risk of nephrotoxicity. The manufacturer recommends 750 to 1000 mL of normal saline or 5% dextrose solution prior to the first infusion of foscarnet to establish diuresis, then 500 mL (for 40 to 60 mg/kg dose of foscarnet) or 750 to 1000 mL (for 90 to 120 mg/kg dose of foscarnet) of hydration fluid concurrently with each subsequent foscarnet infusion. Foscarnet should be used with caution in patients with abnormal renal function because reduced plasma clearance of foscarnet will result in elevated plasma levels. Foscarnet dosing must be individualized according to the patient's renal function status. The use of foscarnet is not recommended in patients with severe renal impairment indicated by a CrCl < 0.4 mL/min/kg and in those patients undergoing hemodialysis because dosage guidelines have not been established.