Strong correlation of lumefantrine concentrations in capillary and venous plasma from malaria patients

Background Lumefantrine is a long-acting antimalarial drug with an elimination half-life of over 3 days and protein binding of 99 percent. Correlation of lumefantrine concentrations from capillary plasma via fingerprick (C-c) versus venous plasma (C-v) remains to be defined. Methods Venous and capillary plasma samples were collected simultaneously from children, pregnant women, and non-pregnant adults at 2, 24, 120hr post last dose of a standard 3-day artemether-lumefantrine regimen they received for uncomplicated malaria. Some of the enrolled children and pregnant women were also HIV-infected. Samples were analyzed via liquid chromatography tandem mass spectrometry. Linear regression analysis was performed using the program Stata (R) SE12.1. Results In children, the linear regression equations for C-c vs C-v at 2, 24, and 120hr (day 7) post dose are [C-c] = 1.05*[C-v]+ 95.0 (n = 142, R-2 = 0.977), [C-c] = 0.995*[C-v]+ 56.7 (n = 147, R-2 = 0.990) and [C-c] = 0.958*[C-v]+ 18.6 (n = 139, R-2 = 0.994), respectively. For pregnant women, the equations are [C-c] = 1.04*[C-v]+ 68.1 (n = 43, R-2 = 0.990), [C-c] = 0.997*[C-v]+ 37.3 (n = 43, R-2 = 0.993) and [C-c] = 0.941*[C-v]+ 11.1 (n = 41, R-2 = 0.941), respectively. For non-pregnant adults, the equations are [C-c] = 1.05*[C-v]-117 (n = 32, R-2 = 0.958), [C-c] = 0.962*[C-v]+ 9.21 (n = 32, R-2 = 0.964) and [C-c] = 1.04*[C-v]-40.1 (n = 32, R-2 = 0.988), respectively. In summary, a linear relationship with a slope of similar to 1 was found for capillary and venous lumefantrine levels in children, pregnant women and non-pregnant adults at 2hr, 24hr and 120hr post last dose, representing absorption, distribution, and elimination phases. Conclusions Capillary and venous plasma concentration of lumefantrine can be used interchangeably at 1: 1 ratio. Capillary sampling method via finger prick is a suitable alternative for sample collection in clinical studies.