Background: Pharmacokinetics, safety and antiviral activity of twice-daily fosamprenavir with or without ritonavir were evaluated in 2- to 18-year-old protease inhibitor–naïve and -experienced HIV-1–infected children.
Methods: Serial pharmacokinetic samples were collected at week 2 and predose samples every 4–12 weeks. Safety and plasma HIV-1 RNA were monitored every 4–12 weeks.
Results: Twenty protease inhibitor–naïve 2- to <6-year-old subjects received antiretroviral treatment including unboosted fosamprenavir twice-daily, whereas 89 protease inhibitor–naïve and -experienced 2- to 18-year-old subjects received fosamprenavir/ritonavir-containing therapy twice-daily. Median fosamprenavir exposure was 891 days (range 15–1805 days), with 88% exposed >48 weeks. Twice-daily doses of fosamprenavir/ritonavir 23/3 mg/kg in 2- to <6-year olds, 18/3 mg/kg in ≥6-year olds and 700/100 mg in adolescents achieved plasma amprenavir exposures comparable with or higher than 700/100 mg twice-daily in adults while fosamprenavir 30 mg/kg twice-daily in 2- to <6-year olds led to exposures higher than 1400 mg twice-daily in adults. The proportion of subjects with HIV-1 RNA <400 copies/mL at week 48 was 60% for fosamprenavir and 53–74% for fosamprenavir/ritonavir (intent-to-treat [exposed], snapshot analysis). Median increases in absolute and relative (percentage) CD4 counts from baseline to week 48 occurred in both the fosamprenavir (340 cells/mm3; 8%) and fosamprenavir/ritonavir group (190 cells/mm3; 8%). The most common adverse events were vomiting, cough, and diarrhea; 18 subjects experienced serious adverse events, including 9 with suspected abacavir hypersensitivity.
Conclusions: Fosamprenavir regimens administered to HIV-1–infected children aged 2–18 years were generally well-tolerated and provided sustained antiviral activity over 48 weeks, with plasma amprenavir exposures comparable with or higher than adults.
From the *Sant Joan de Déu Hospital, Barcelona, Spain; †Dr. Victor Babes Hospital for Infectious and Tropical Diseases, Bucharest, Romania; ‡GlaxoSmithKline, Uxbridge, United Kingdom; §GlaxoSmithKline, Research Triangle Park, NC; ¶Tygerberg Children’s Hospital, Tygerberg, South Africa; and ‖Hospital Infantil La Fe, Valencia, Spain.
Accepted for publication May 14, 2013.
This study is sponsored and funded by ViiV Healthcare; GlaxoSmithKline is responsible for implementing and managing all aspects of this study.
M.C. received support from a grant from ViiV Healthcare and payment for lectures, including service on speakers’ bureaus, from Abbott Laboratories. K.C., H.P.G., S.L.F., M.B.W., N.G., L.L.R., Y.L., T.P. and J.S. are employees of GlaxoSmithKline. The authors have no other funding or conflicts of interest to disclose
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