Oral ganciclovir in pediatric transplant recipients: a pharmacokinetic study

An oral formulation of ganciclovir (GAN) has been shown to be effective as prophylaxis of cytomegalovirus (CMV) after liver transplantation in an adult population. There are no data on the use or dose of oral GAN in pediatric transplant recipients. We evaluated the pharmacokinetics of oral GAN in a group of such patients. Nine patients (4 kidney and 5 liver transplant recipients, age 0.9-13 yr) were treated with the commercial formulation of oral GAN after transplant. All patients were considered at risk for CMV disease based on the use of anti-lymphocyte antibody (n = 5), and/or the use of a CMV positive organ in a CMV negative recipient (n = 5) or based on being a recipient of a liver transplant (n = 4). They received oral GAN for 84 +/- 29 d. All recipients had normal renal function as estimated by the Schwartz formula. While on a stable dose of oral GAN for at least 4 d (mean +/- SD 8.4 +/- 7, range 4-27 d), 1-ml serum samples were obtained before and at various times after dosing for the measurement of GAN levels. GAN levels were determined at a central laboratory by high-performance liquid chromatography. In 7 of the patients, a sufficient number of levels were obtained post-dosing to calculate the area under the curve using the linear trapezoidal rule. Cmin, the morning trough concentration, and Cmax, the peak concentration, were determined by inspection. Doses of oral GAN were increased if Cmin levels were less than 0.5-1.0 microgram/ml. Adequate levels of GAN were achieved in these patients at doses of 21.8-38.5 mg/kg or 568-990 mg/m2 every 8 h. There was a better correlation between the maximum GAN blood concentration and body surface area (R2 = 0.52, p = 0.008) than with body weight (R2 = 0.36, p = 0.04). Oral GAN was well tolerated in the 7 patients without evidence of leukopenia, thrombocytopenia, or nephrotoxicity. No CMV disease occurred, although one patient had probable CMV syndrome with the development CMV IgM antibodies. These data suggest that oral GAN may be safely administered to pediatric transplant recipients. With normal renal function, the dosing should be in the range 20-40 mg/kg or 500-700 mg/m2 q 8 h. Further data in children with impaired renal function is required.