Malaria chemotherapy: resistance to quinoline containing drugs in Plasmodium falciparum

Resistance to quinoline containing drugs, particularly chloroquine (CQ), is a major impediment to the successful chemotherapy and prophylaxis of malaria. CQ-resistant parasites fail to accumulate as much drug as their sensitive counterparts and two major hypotheses have been proposed to account for this phenomenon. CQ-resistant parasites are thought to maintain lower intracellular drug levels by means of an active efflux system, similar to that found in multi-drug resistant cancer cells, despite major differences in both the genetic and biochemical manifestations of drug resistance in the two cell types. Alternatively, CQ-resistance could be linked to a defective CQ uptake mechanism, possibly an impaired acidification process in the food vacuole of the resistant parasite. These two theories are discussed in detail in the following review. The potential of pharmacological intervention to override these resistance mechanisms is also discussed.