Bidirectional transport of four novel antimalarial compounds was determined using Caco-2 cell monolayers. P glycoprotein-mediated efflux was greatest for pyronaridine (5 to 20 microM) and low for naphthoquine (5 microM). With 20 microM naphthoquine, net efflux was blocked, suggesting saturation of the transporter. Piperaquine and dihydroartemisinin were not transported by the system.
