Potentiation of the antimalarial activity of atovaquone by doxycycline against Plasmodium falciparum in vitro.

The effect of doxycycline, obtained from human volunteers administered doxycycline, on the minimum inhibitory concentration (MIC) of atovaquone was determined against the K1 and FC27 isolates of Plasmodium falciparum in vitro. Doxycycline concentrations ranging from 0.10-1.18 microg/ml added to atovaquone produced MIC ratios [atovaquone + doxycycline/atovaquone alone] ranging from 0.38 to 0.70. These results suggest that the antimalarial activity of atovaquone is potentiated by doxycycline. Additionally, these drugs may be rational partners for the treatment and prophylaxis of falciparum malaria.