Chloroquine and desethylchloroquine concentrations in blood cells and plasma from Indian patients infected with sensitive or resistant Plasmodium falciparum

The sensitivities of 61 Indian cases of Plasmodium falciparum malaria to ch loroquine (CQ) were investigated using in-vitro and in-vivo methods. Concen trations of CQ and desethylchloroquine (DCQ) in blood cells and plasma from CQ-sensitive and -resistant cases were determined 2 and 7 days after initi ation of treatment, by HPLC. On day 2, the mean CQ concentrations in the sa mples collected from the sensitive cases were higher than those in the samp les from the resistant patients, in plasma (0.47 v. 0.32 mu g/ml; P < 0.02) and particularly in the blood cells (1.51 v. 0.46 mu g/ml; P < 0.001). By day 7, however, the CQ concentrations in the two groups were similar. Altho ugh, on day 2, the mean ratio of the CQ to DCQ concentrations was significa ntly higher in the blood cells from the sensitive group than in those from the resistant cases (P < 0.01), the CQ/DCQ ratios for the plasma were simil ar for the two groups. Similarly, the mean ratio between the blood-cell con centration of CQ on day 2 and the concurrent plasma concentration (BPr) was also relatively high in the sensitive group (P < 0.001).