Concentrations of chloroquine and desethylchloroquine in capillary blood dried on filter paper during and after treatment of Tanzanian children infected with Plasmodium falciparum.

Chloroquine and desethylchloroquine concentrations were determined in capillary whole blood dried on filter paper. The samples were obtained from 20 Tanzanian children before, during and after standard treatment of Plasmodium falciparum malaria with a total dose of 25 mg chloroquine base/kg. Samples were obtained before each dose and then daily up to one week after initiation of treatment. Chloroquine concentrations were consistently above 1.0 micromol/L only on the day after termination of treatment. The inter-individual range of area under the curve (AUC) was 5.6 fold for chloroquine and 8.8 fold for desethylchloroquine. The AUC and elimination time of chloroquine and desethyl-chloroquine was less than the median in two children with persisting parasitemia despite treatment. Thus, pharmaco-kinetics of chloroquine in the individual might be important to consider when P. falciparum parasites are classified in different categories of resistance.