Development of a resistant line of Plasmodium berghei to sodium artesunate

A resistant line of Plasmodium berghei to sodium artesunate (sodium salt of succinyl dihydroartemisinin, Art, first synthesized by Chinese scientists) was successfully developed in consecutive passages by administering doses of Art increasingly. The index (I of passage 21 over 85 d was 29.3. Up to now, passage 80 has been developed and the resistance was stable. During passaging 400 mg/kg of Art was administered ip to mice at each passage (every10 d), the resistance was stable. If the parasites were passaged in absence of drug pressure, the resistance to Art lost gradually up to passage 21. The I for pyrimethamine, artemisinin and artemether were 1.38, 2.19, and 2.23. respectively. No cross-resistance to chloroquine was found.