Pharmacokinetics of lopinavir in HIV type-1-infected children taking the new tablet formulation once daily

Background: Recently, a new tablet formulation of the widely used HIV protease inhibitor lopinavir/ritonavir was licensed. Here, we present a pilot study of the pharmacokinetics of the new adult tablet formulation taken once daily in children. Methods: Lopinavir pharmacokinetics of the new adult tablet formulation were evaluated in 15 HIV type-1-infected children between 4 and 15 years of age. A target dose of 460/115 mg/m² was administered once daily. Plasma concentrations of lopinavir over the course of 24 h were determined with a validated HPLC method. Results: The median lopinavir dose was 498 mg/m² (range 424-548). The mean ±SD for lopinavir area under the 24 h curve was 217.9 ±44.9 mg/l•h, the maximum concentration was 14.8 ±2.4 mg/l and the concentration 24 h after intake was 3.1 ±2.6 mg/l. The half-life of lopinavir was 5.8 ±4.5 h and the median time to maximum concentration was 5.8 h (range 1.8-12.2). Overall, the tablet formulation resulted in greater exposure to lopinavir with less variability compared with the soft-gel capsule formulation. All children treated with the new adult tablet formulation had undetectable viral loads (<50 copies/ml) during 24 weeks follow-up. Conclusions: The tablet formulation could probably result in improved lopinavir dosing and increases the feasibility of once-daily lopinavir/ ritonavir-based regimens in children.