Because of immature hepatic metabolism, lopinavir could present specific pharmacokinetics in the first weeks of life. We aimed at determining the optimal dosing regimen in neonates and infants weighing 1 to 10.5 kg.METHODS
Lopinavir/ritonavir (LPV/r) pharmacokinetics were studied in 96 infants using a population approach.RESULTS
A one-compartment model described LPV/r pharmacokinetics. Normalized to a 70 kg adult using allometry, clearance (CL/F) and distribution volume (V/F) estimates were 5.87 l h−1 70 kg−1 and 91.7 l 70 kg−1. The relative bioavailabilty, F, increased with post-menstrual age (PMA) and reached 50% of the adult value at 39.7 weeks.CONCLUSIONS
Size and PMA explained some CL/F and V/F variability in neonates/infants. Based upon trough concentration limitations, suggested LPV/r dosing regimens were 40 mg 12 h−1, 80 mg 12 h−1 and 120 mg 12 h−1 in the 1–2 kg, 2–6 kg and 6–10 kg group, respectively.