Forty-eight-week evaluation of lopinavir/ritonavir, a new protease inhibitor, in human immunodeficiency virus-infected children

Background. Lopinavir/ritonavir has demonstrated antiviral activity in the HIV-infected adult. Subjects. The objective of this study was to investigate a liquid coformulation of lopinavir/ritonavir, in combination with reverse transcriptase inhibitors, in HIV-infected children. Methods. One hundred antiretroviral (ARV)-naive and ARV-experienced, nonnucleoside reverse transcriptase inhibitor-naive children between 6 months and 12 years of age participated in this Phase I/II, open label, multicenter trial. Subjects initially received either 230/57.5 mg/m² or 300/75 mg/m² lopinavir/ritonavir twice daily; ARV-naive subjects also received stavudine and lamivudine, whereas ARV-experienced subjects also received nevirapine and one or two nucleoside reverse transcriptase inhibitors. Lopinavir/ ritonavir pharmacokinetics, safety and efficacy were evaluated. Results. All subjects were escalated to the 300/75 mg/m² twice daily dose based on results from an interim pharmacokinetic and safety evaluation. The pharmacokinetics of lopinavir did not appear to be dependent on age when dosing was based on body surface area but were decreased on coadministration with nevirapine. Overall 79% of subjects had HIV RNA levels <400 copies/ml at Week 48 (intent-to-treat: missing = failure). Mean increases in absolute and relative (percent) CD4 counts from baseline to Week 48 were observed in both ARV-naive subjects (404 cells/mm³; 10.3%) and ARV-experienced subjects (284 cells/mm³; 5.9%). Only one subject prematurely discontinued the study because of a study drug-related adverse event. Conclusions. The liquid coformulation of lopinavir/ritonavir demonstrated durable antiviral activity and was safe and well-tolerated after 48 weeks of treatment in HIV-infected children.