Chloroquine-resistant Plasmodium falciparum accumulate significantly less chloroquine than susceptical parasites, and this is thought to be the basis of their resistance ( Fitch, 1970 ). Martin et. al ( 1987 ), recently demonstrated that in the presence of verapamil, a calcium channel blocker, chloroquine-resistant P falciparum becomes chloroquine-sensitive, with an increase in the chloroquine accumulation.The mechanism of such reversal has yet to be elucidated
