Background: Cidofovir is an antiviral agent used for the treatment of cytomegalovirus infection in patients with acquired immunodeficiency syndrome. Because cidofovir is primarily eliminated by the kidneys and because its main adverse effect is nephrotoxicity, an understanding of the pharmacokinetic disposition of cidofovir in patients with renal insufficiency is necessary.
Methods: Twenty-four subjects were enrolled into this study and were divided into 6 groups depending on their degree of renal dysfunction, including subjects receiving maintenance continuous ambulatory peritoneal dialysis and high-flux hemodialysis. The creatinine clearance (CLCR) for subjects not receiving dialysis ranged from 12 to 164 mL/min. Each subject received a single 0.5 mg/kg intravenous dose of cidofovir over 1 hour. Subjects not receiving dialysis were given intravenous hydration with 1 L normal saline solution and concomitant oral probenecid. Serial serum and urine samples were collected to determine pharmacokinetic parameters with use of noncompartmental methods.
Results: Mean +/- SD cidofovir clearance (CL) in control subjects (normal renal function; n = 5) was 1.7 +/- 0.1 mL/min/kg, which decreased with declining renal function as indicated by the regression equation: CL (mL/min/kg) = 0.94 x CLCR (mL/min/kg) + 0.064 (r2 = 0.91). Mean volume of distribution at steady state did not change significantly in subjects with kidney disease and cidofovir serum elimination half-life was significantly increased in subjects with severe renal impairment. Cidofovir was not significantly cleared during continuous ambulatory peritoneal dialysis, but high-flux hemodialysis resulted in the removal of 52% +/- 11% of the dose administered.
Conclusion: The significant (P < .001) correlation observed between CLCR and CL in subjects with varying degrees of renal insufficiency indicates that aggressive dosage reduction of cidofovir would be necessary in subjects with kidney disease to ensure comparable drug exposure based on serum levels.