In vitro and in vivo interaction of synthetic peroxide RBx11160 (OZ277) with piperaquine in Plasmodium models

RBx11160 (OZ277) is a promising antimalarial drug candidate that Ranbaxy Laboratories Limited and Medicines for Malaria Venture (MMV) are currently developing as a fixed combination with piperaquine. Here, we describe the in vitro (Plasmodium falciparum) and in vivo (Plasmodium berghei) activities of piperaquine in combination with RBx11160 and artemether. In vitro, both combinations demonstrated a slight tendency towards antagonism with mean sums of fractional inhibitory concentrations (mean ΣFICs) of 1.5. In vivo, piperaquine and artemether were borderline antagonistic (mean ΣFIC of 1.4). However, an additive in vivo interaction of piperaquine and RBx11160 (mean ΣFIC of 1.1) was identified, suggesting that a RBx11160-piperaquine combination therapy in humans should allow each molecule to exert its full antimalarial effect.