AyFlux / Experimental

AyFlux Neonatal

IV acyclovir clearance across maturation

Research only. Reproduces a published population equation; not an individual prediction or dosing recommendation.

Compare two postmenstrual ages within the study range of 25–41 weeks. Postmenstrual age is gestational age at birth plus time since birth.

Typical acyclovir clearance by postmenstrual agePublished model curve from 25 to 41 weeks, with two selected ages marked. Numerical values appear in the table below.
Typical model predictions, not observed infant data
ComparisonPMA (weeks)Clearance (L/h/kg)

Published equation

CL=0.305×(PMA31.3 weeks)3.02

CL is typical clearance in L/h/kg. Both infants are compared per kilogram, so the curve isolates the model’s age effect rather than a difference in body weight.

Evidence and scope

Sampson and colleagues studied 28 preterm and term infants. The equation predicts a 4.45-fold clearance increase between 25 and 41 weeks PMA. This page reproduces that relationship; it does not independently validate it against concentration measurements.

The equation has no adjustable kidney-function term. Do not interpret these estimates as predictions for renal impairment, dialysis, or ages outside the source range. No adult clearance equation, toxicity threshold, or treatment schedule is applied.

Sampson MR et al. Population Pharmacokinetics of Intravenous Acyclovir in Preterm and Term Infants. Pediatr Infect Dis J. 2014;33:42–49. DOI · NIH study synopsis and equation