In vitro sensitivity of Plasmodium falciparum to halofantrine compared with chloroquine, quinine and mefloquine in the region of Bobo-Dioulasso, Burkina Faso (West Africa).

The in vitro sensitivity of P. falciparum drug-resistant isolates was evaluated in the region of Bobo-Dioulasso during the 1995 and 1996 rainy seasons. Two routinely used antimalarials (chloroquine and quinine) and two new antimalarials (mefloquine and halofantrine) were assessed using 24-hour in vitro cultures with tritiated hypoxanthine and a parasite density > or = 4,000/microl of blood. The proportion of chloroquine-resistant isolates was 20% in 1995 and 19% in 1996, whilst in 1996, the proportion of isolates resistant to halofantrine was greater than in 1995 (9.6% versus 1%). No significant differences were seen in the mean IC50 values in relation to the susceptibility of chloroquine-resistant or chloroquine-sensitive isolates to mefloquine and halofantrine. In the case of quinine, the mean IC50 values were significantly higher in chloroquine-resistant isolates than in chloroquine-sensitive ones. A significant positive correlation was found between the following IC50 values: chloroquine versus quinine, quinine versus mefloquine and mefloquine versus halofantrine.