The PTN open-label study to describe the pharmacokinetics (PK) of acyclovir in premature infants has concluded, with results recently published in the Pediatric Infectious Diseases Journal.

Acyclovir is a drug used to treat herpes simplex virus (HSV) infections in infants. HSV is a very serious infection in those <6 months of age, often resulting in death or profound mental retardation. Appropriate dosing of acyclovir is known for adults and children but has not been adequately studied in full-term or premature neonates.

This study examined acyclovir levels in the blood of premature and term infants who were placed on the drug to treat a suspected HSV infection, thereby determining the appropriate dose in this vulnerable population. Investigators found that infant maturity as measured by post-menstrual age* is associated with the infant body’s ability to clear the drug; in short, they determined that less frequent dosing is needed in younger infants to achieve optimal therapeutic benefit.

The study was conducted at two sites — Duke University Medical Center in Durham, North Carolina, and Wesley Medical Center in Wichita, Kansas. Site teams headed by Robert Lenfestey (Duke) and Paula Delmore (Wesley) enrolled 32 patients over the 9-month study. Next steps will involve a retrospective analysis of data from infants who received high-dose acyclovir; this information will support proposed label changes submitted to the Food and Drug Administration for use of acyclovir in infants.

* Post-menstrual age is the time elapsed between the first day of the mother’s last menstrual period and the infant’s birth, plus the time elapsed since birth.