Kinetics of the uptake and elimination of chloroquine in children with malaria.

1 Ten children with Plasmodium falciparum malaria were treated with 25 mg/kg chloroquine over 3 days and observed for 7 days. 2 Chloroquine was determined in the red blood cells and plasma, and the red blood cell/plasma chloroquine concentration ratio was correlated with the disappearance of the parasites from the blood. It was found that this ratio decreased with the disappearance of the parasites and remained almost steady after the parasites had disappeared completely from the blood. 3 The half-life (t1/2) and the elimination rate constant of the "terminal' elimination slope (lambda beta) of the plasma log concentration-time curve were estimated to be 135.9 +/- 9.92 h and 0.005 +/- 0.001 h-1 (s.d.) respectively. 4 The t1/2 and lambda beta calculated from the red blood cell log concentration-time curve were not significantly different from the corresponding values calculated from the plasma log concentration-time curve.