Pharmacokinetics of ganciclovir during continuous venovenous hemodiafiltration in critically ill patients.

Ganciclovir is an antiviral agent that is frequently used in critically ill patients with cytomegalovirus (CMV) infections. Continuous venovenous hemodiafiltration (CVVHDF) is a common extracorporeal renal replacement therapy in intensive care unit patients. The aim of this study was to investigate the pharmacokinetics of ganciclovir in anuric patients undergoing CVVHDF. Population pharmacokinetic analysis was performed for nine critically ill patients with proven or suspected CMV infection who were undergoing CVVHDF. All patients received a single dose of ganciclovir at 5 mg/kg of body weight intravenously. Serum and ultradiafiltrate concentrations were assessed by high-performance liquid chromatography, and these data were used for pharmacokinetic analysis. Mean peak and trough prefilter ganciclovir concentrations were 11.8 ± 3.5 mg/liter and 2.4 ± 0.7 mg/liter, respectively. The pharmacokinetic parameters elimination half-life (24.2 ± 7.6 h), volume of distribution (81.2 ± 38.3 liters), sieving coefficient (0.76 ± 0.1), total clearance (2.7 ± 1.2 liters/h), and clearance of CVVHDF (1.5 ± 0.2 liters/h) were determined. Based on population pharmacokinetic simulations with respect to a target area under the curve (AUC) of 50 mg · h/liter and a trough level of 2 mg/liter, a ganciclovir dose of 2.5 mg/kg once daily seems to be adequate for anuric critically ill patients during CVVHDF.

A simple, sensitive determination of ganciclovir in infant plasma by high-performance liquid chromatography with fluorescence detection.

This study developed a simple and sensitive method using reversed-phase high-performance liquid chromatography (HPLC) for ganciclovir (GCV) plasma concentrations in cytomegalovirus infectious infants with hearing loss. The method involves a simple protein precipitation procedure that uses no solid-phase or liquid-liquid extraction. The HPLC separation was carried out on a Cadenza CD-C(18) column (3 microm, 4.6 mm x 150 mm) with phosphate buffer (pH 2.5, 25 mM) containing 1% methanol-acetonitrile mixture (4:3, v/v) as a mobile phase at a 0.7 mL/min flow rate. GCV was detected using a fluorescence detection (lambdaex/em: 265/380 nm). The quantification limit was 0.025 microg/mL for 100 microL of plasma sample at which good intra- and inter-assay coefficient of variation values (< 4.96%) and recoveries (94.9-96.5%) were established.

Simultaneous determination of acyclovir, ganciclovir, and (R)-9-[4-hydroxy-2-(hydroxymethyl)butyl]guanine in human plasma using high-performance liquid chromatography.

Acyclovir, ganciclovir and (R)-9-[4-hydroxy-2-(hydroxymethyl)butyl]guanine are active in vitro against the Epstein-Barr virus (EBV) but their in vivo anti-EBV activity is not well understood. We developed a novel, sensitive high-performance liquid chromatography assay with ultraviolet detection for measuring acyclovir, ganciclovir and (R)-9-[4-hydroxy-2-(hydroxymethyl)butyl]guanine in human plasma to identify quantitative relationships between in vitro anti-EBV activity and therapeutic response. Characteristics of the assay include a low plasma volume (200 microL), perchloric acid protein precipitation, use of penciclovir as the internal standard, run times less than 8 min and a 50 ng/mL lower limit of quantification. The within- and between-assay variability is 0.7-4.8 and 1.0-7.9%, respectively. Accuracy for all three drugs ranges from 89.5 to 106.4% for four quality controls (50, 100, 1000 and 10,000 ng/mL). This assay supports pharmacokinetic and pharmacodynamic studies of candidate anti-EBV drugs in children and adults with EBV infections.

Pharmacokinetic and pharmacodynamic assessment of oral valganciclovir in the treatment of symptomatic congenital cytomegalovirus disease.

BACKGROUND: Intravenous ganciclovir administered for 6 weeks improves hearing outcomes in infants with symptomatic congenital cytomegalovirus (CMV) disease involving the central nervous system. METHODS: Twenty-four subjects received antiviral therapy for 6 weeks. Serial pharmacokinetic assessments were performed after administration of valganciclovir oral solution and of intravenous ganciclovir. RESULTS: On the basis of a previous pharmacokinetic study of the use of intravenous ganciclovir in this population, a target AUC12 (area under the concentration-time curve over a 12-h period) of 27 mg x h/L was defined. The median dose of oral valganciclovir administered in the present trial was 16 mg/kg, which produced a geometric mean AUC12 of 27.4 mg x h/L. The bioavailability of valganciclovir was 41.1%. Of the 18 subjects who had detectable CMV in whole blood at baseline or during therapy, 11 had <4 log viral DNA copies/mL at baseline, and 7 had > or =4 log viral DNA copies/mL at baseline; subjects who started the study with the higher viral burden experienced greater decreases in viral load but did not clear virus during the 42-day course of therapy. Neutropenia of grade 3 or 4 developed in 38% of subjects. CONCLUSIONS: In neonates with symptomatic congenital CMV disease, valganciclovir oral solution provides plasma concentrations of ganciclovir comparable to those achieved with administration of intravenous ganciclovir. The results of the present study cannot be extrapolated to extemporaneously compounded liquid formulations of valganciclovir.

Pharmacokinetic assessment of oral ganciclovir in lung transplant recipients with cystic fibrosis.

Oral ganciclovir has been used as prophylaxis and therapy against cytomegalovirus in patients with HIV infection and following organ transplantation. Oral ganciclovir has clear practical advantages over intravenous ganciclovir but has a relatively low bioavailability and this may be problematic in at-risk patients with malabsorption. The bioavailability and therefore therapeutic potential of oral ganciclovir in cystic fibrosis (CF) patients post-lung transplant (LT) might be expected to be inadequate given the high incidence of malabsorption in these patients. An 8 h pharmacokinetic study was performed in 12 CF patients 160 +/- 122 days post-transplant who had been taking 1 g oral ganciclovir tds for 3 days with food (plus normal enzyme supplements). Mean (range) serum creatinine was 150 Imol/L (70-280). Blood was sampled at 0.5, 1, 2, 3, 4, 6 and 8 h post-final dose. Plasma was stored at -20 degrees C and later analysed by highperformance liquid chromatography. Mean peak concentration (C(max)) was 4.8 mg/L (0. 96-12.8), mean minimum concentration (C(min)) was 3.6 mg/L (0.78-11. 7) and mean area under the curve (AUC) was 35.4 mg.8 h/L (8-99). C(max), C(min) and AUC correlated significantly with one another (P < 0.001) as well as with serum creatinine and creatinine clearance (P < 0.01). When corrected for alterations in renal function, plasma oral ganciclovir levels are as predicted for other transplant populations. Three days of oral ganciclovir results in therapeutically useful plasma drug levels in the CF LT population, despite a background of general malabsorption. C(max), C(min) and AUC are highly correlated, allowing for the possibility of steady-state drug monitoring to confirm that the recommended dosing algorithm produces appropriate plasma levels.