Distribution of chloroquine and its metabolite desethyl-chloroquine in human blood cells and its implication for the quantitative determination of these compounds in serum and plasma.
The amount of chloroquine and desethyl-chloroquine was determined in samples of total blood and in blood cell fractions from three normal subjects after one oral dose of 1000 mg of chloroquine diphosphate. About 70-85% of the total whole blood content of chloroquine and its metabolite desethyl-chloroquine were recovered in blood cells isolated from whole blood, indicating that these compounds have a high cell/plasma concentration ratio. They were mainly present in thrombocytes and granulocytes. A study of 40 patients taking chloroquine regularly as a treatment for rheumatoid arthritis showed significantly higher concentrations of chloroquine and desethyl-chloroquine in serum than in plasma. The concentration of chloroquine was about two times higher in serum than in plasma and for desethyl-chloroquine the concentration was about four times higher in serum than in plasma. These differences may be explained by a release of chloroquine and desethyl-chloroquine from thrombocytes during the coagulation of blood. The practical implication of the results is that the samples taken for chloroquine determination must be clearly identified as serum or plasma.
D001172:Arthritis, Rheumatoid / Q000188:drug therapy; D001792:Blood Platelets / Q000032:analysis / Q000378:metabolism*; D002469:Cell Separation / Q000379:methods; D002738:Chloroquine / Q000031:analogs & derivatives* / Q000097:blood / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D004912:Erythrocytes / Q000032:analysis / Q000378:metabolism*; D006098:Granulocytes / Q000032:analysis / Q000378:metabolism*; D006801:Humans
D002738:Chloroquine; C007278:desethylchloroquine