Briefly, male BALB/c mice were infected intrape ritoneally with 2��107 infected erythrocytes on day 0. Test compounds were administered orally at a volume of 10 mL/kg as once or twice daily doses every 24 hours for four days. On day 3, per cent parasitaemia was estimated microscopically from a Giemsa stained blood smear. The effect of the test compound on parasite nothing growth was calculated as the difference between the mean value of the control group and those of the experimental group and expressed as per cent reduc tion. Reference anti malarial compounds were used as positive controls and the results obtained matched those published in the literature. Pharmacokinetics were analysed in healthy as well as infected mice. Data from healthy mice were used for designing the dosing regimen for the efficacy studies.

In infected mice, pharmacokinetics was carried out on day 2 of compound administration. One mouse per time point was sampled according to the fast mouse pharmacokinetic protocol. Plasmodium falciparum huSCID mouse model In vivo testing using this model was performed by GSK at Tres Cantos, against P. falciparum 3D7 growing in peripheral blood of female NOD scid IL 2R��null mice engrafted with human erythrocytes, i e, a humanized mouse model, following published protocols. Briefly, animals were infected intravenously with 20��106 infected erythrocytes on day 0. Test compounds were administered orally at a volume of 20 mL/kg or subcutaneously in an appropriate inactive vehicle. Dosing was initiated at the maximum tolerated dose in mice on day 3 after infection and continued once daily for four days.

Each experimental group was n 3 mice unless otherwise stated. Control animals received vehicle only and a quality control assay used chloroquine at target doses of 3 mg/kg and 7 mg/kg. Venous blood samples for parasitology were taken at days 3, 5, and 7 after infection. Anti malarial efficacy was assessed using a standard four day test and blood parasitaemia was measured by fluorescence activated cell sorting analysis. The limit of detection was 0. 01%. The number of parasites 106 cells was recorded and data were analysed by non linear fitting to a logistic equation of log10 versus the dose level administered. Per cent parasitaemia at day 7 after infection in treated versus control animals was analysed using a one factor ANOVA with Tukeys post test analysis.

If there was a significant difference then the ED50 was calcu lated as the dose in mg/kg that reduced parasitaemia at day 7 after infection by 50% with respect to vehicle treated mice. ED90 Anacetrapib was calculated similarly. Analysis was performed using WinNonlin 5. 2 and GraphPad Prism 5. 0. The pharmacokinetics of compounds after oral admin istration was determined concurrently in the same mice used for the therapeutic efficacy assay. Samples were taken at 0. 25, 0. 5, 1, 3, 6, 8, and 24 hours after the first dose.