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.