Fig 3. Optimisation of the atovaquone-proguanil treatment regime.

(a) Trophozoite stage parasites (strain K1) were treated with a 2-fold dose series of atovaquone (ATQ), proguanil (PG) or a constant-ratio combination of both drugs (ATQ+PG) for 48 hours. The mid-point was equated to the previously determined ED₅₀ value for each drug. (b) Was a replica of (a) but with an increased atovaquone dose series. (c) Ring stage parasites were treated for 72 hours with a 3-point constant-ratio dose series of atovaquone and proguanil either alone or in combination. SG-FCM method was used to analyse parasite growth. The parasitaemia of drug treated samples was determined relative to untreated controls (100% parasitaemia). Triplicate samples were used to derive error bars based on standard error of the mean (SEM).