RESUMO
To study pharmacokinetics of chloroquine in healthy adult Pakistani subjects and evaluate the role of pharmacokinetic factor in the dynamics of drug resistance in Plasmodium falciparum. This was an experimental study. The study was conducted at National Institute of Health Islamabad during the year 2001. Eleven healthy male volunteers, who met the defined inclusion criteria, were recruited into the study after obtaining informed consent. Blood samples were drawn at specified time intervals before and after administration of chloroquine tablets equivalent to 600 mg base. Plasma was separated and extracted according to the methods described in literature. Chloroquine estimation was carried out using High Performance Liquid Chromatography. Data of plasma concentration of chloroquine in 10 healthy volunteers is reported in this study. Mean pharmacokinetic parameters worked out from the data are Area under the Curve = 10.827, Peak Concentration = 201 ng/ml, Time to Peak = 6.1 hours, Half Life Phase-1 = 2.62 hours, Half Life Phase-2 = 41 hours, Volume of Distribution = 149.24 Litres, Clearance = 55.95 litres/hour Mean Residence Time = 58.53 hours. The pharmacokinetic profile of chloroquine in healthy adult male Pakistani subjects is comparable to that described in other ethnic populations of the world. The pharmacokinetic factor may play a role in selection of partially chloroquine-resistant parasites when the drug is used for prophylaxis of malaria on weekly basis