Plasmodium vivax is an important human pathogen causing malaria in more 
temperate climates of the world. Similar to Plasmodium falciparum, the causative 
agent for malaria tropica, drug resistance is beginning to emerge for this 
parasite species and this hampers adequate treatment of infection. We have used 
a short-term ex vivo drug assay to monitor activity of OZ277 (RBx-11160), a 
fully synthetic anti-malarial peroxide, and the diamidine DB75 against P. vivax. 
For both compounds as well as the anti-malarial reference compounds artesunate, 
artemether, and chloroquine, the in vitro IC(50) values were determined in 
one-cycle hypoxanthine incorporation assays. Results from such assays were found 
to be very similar compared to IC(50) values obtained from one-cycle P. 
falciparum hypoxanthine assays. We demonstrate the anti-parasite activity of 
OZ277 and the reference compounds to be faster than that of DB75. These data 
warrant clinical testing of OZ277 against P. vivax malaria and support recent 
data on clinical activity against P. vivax for DB75.