The effects of serum lipids on the in vitro activity of lumefantrine and atovaquone against Plasmodium falciparum.

Journal article

BACKGROUND: Lumefantrine and atovaquone are highly lipophilic anti-malarial drugs. As a consequence absorption is increased when the drugs are taken together with a fatty meal, but the free fraction of active drug decreases in the presence of triglyceride-rich plasma lipoproteins. In this study, the consequences of lipidaemia on anti-malarial drug efficacy were assessed in vitro. METHODS: Serum was obtained from non-immune volunteers under fasting conditions and after ingestion of a high fat meal and used in standard Plasmodium falciparum in-vitro susceptibility assays. Anti-malarial drugs, including lumefantrine, atovaquone and chloroquine in five-fold dilutions (range 0.05 ng/ml-1 ug/mL) were diluted in culture medium supplemented with fasting or post-prandial 10% donor serum. The in-vitro drug susceptibility of parasite isolates was determined using the ³H-hypoxanthine uptake inhibition method and expressed as the concentration which gave 50% inhibition of hypoxanthine uptake (IC₅₀). RESULTS: Doubling plasma triglyceride concentrations (from 160 mg/dL to 320 mg/dL), resulted in an approximate doubling of the IC₅₀ for lumefantrine (191 ng/mL to 465 ng/mL, P < 0.01) and a 20-fold increase in the IC₅₀ for atovaquone (0.5 ng/mL to 12 ng/ml; P < 0.01). In contrast, susceptibility to the hydrophilic anti-malarial chloroquine did not change in relation to triglyceride content of the medium. CONCLUSIONS: Lipidaemia reduces the anti-malarial activity of lipophilic anti-malarial drugs. This is an important confounder in laboratory in vitro testing and it could have therapeutic relevance.

Authors: Chotivanich, K; Mungthin, M; Ruengweerayuth, R; Udomsangpetch, R; Dondorp, A

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: BioMed Central
• Journal: Malaria journal
• Volume: 11
• Issue: 1
• Article number: 177
• Publication date: 2012-01-01
• DOI: 10.1186/1475-2875-11-177
• EISSN: 1475-2875
• ISSN: 1475-2875
• Language: English
• Keywords: Parasitic Sensitivity Tests; Fluorenes; Lipids; Plasmodium falciparum; Atovaquone; Ethanolamines; Inhibitory Concentration 50; Humans; Human Experimentation; Antimalarials; Serum