Assessment of acyclovir intraindividual pharmacokinetic variability duringcontinuous hemofiltration, continuous hemodiafiltration, and continuous hemodialysis

The use of intravenous acyclovir can be particularly complicated in pediatr ic patients with evolving renal impairment, because of intraindividual phar macokinetic variability linked to the patient's clinical condition. The obj ective of this study was to use therapeutic drug monitoring data to assess acyclovir intraindividual pharmacokinetic variability during several types of renal replacement therapy. Bayesian adaptive control of acyclovir dosage regimen was performed in a pediatric patient with bone marrow transplant w ho developed severe renal impairment. Acyclovir pharmacokinetic parameter v alues corresponding to the different techniques and periods of renal replac ement therapy were estimated using USCPACK PC Clinical Programs and therape utic drug monitoring data. Results showed a wide intraindividual pharmacoki netic variability during CAVH, CAVHDF, and CVVHD, reflecting not only the p erformance of each dialysis technique but also the difficulty in making use of each one. The acyclovir elimination rate constant was higher during CVV HD compared to CAVH or CAVHDF. Bayesian method appears to he valuable in as sessing intraindividual pharmacokinetic variability, as it allows the clini cian to deal with sparse routine patient data.