How can we do pharmacokinetic studies in the tropics?

Information regarding the pharmacokinetic (PK) and pharmacodynamic (PD) pro perties of a drug provides the basis for optimizing dosing. PK-PD informati on should be obtained from patients representative of the overall target po pulation, but in many tropical hospitals or health care facilities it may b e medically hazardous or logistically difficult for an ill patient or a you ng child to be sampled repeatedly. Traditional methods used to determine th e pharmacokinetic properties of a drug require analysis of a large number o f blood samples per subject. However, using modem statistical methods, spar se datasets (i.e. with assay results from only a few, or as little as one b lood sample per subject) can now be analysed by a method termed 'the popula tion approach'. Modern assay techniques can often be adapted to small blood volumes allowing finger prick blood samples to be taken. One of the major aims of the population approach is to distinguish and characterize patient and disease contributors to inter-individual variance in drug pharmacokinet ics. The purpose of this paper is to explain the basis of the population ap proach, to highlight its advantages compared to traditional methods of anal ysis, and to review the application of the population approach to data from field studies of antimalarial drugs. The design of population pharmacokine tic studies is also discussed briefly. The principles discussed in the pape r are also applicable to pharmacodynamic data.