Development of artemether-resistant line of Plasmodiurn berghei

Using stepwise dose increase and stcpwise dose-relapse methods, an artemether-resistant line (RA line) was developed. It was resistant to the toxic effects of the drug which could cause death of the host. The SD50 of artemether in P berghei N strain was 0.49 mg/kg, and that of the RA line was 68 mg/kg. The RA line was more stable without artemether dosage. The RA line passage 67 was used as the source and passaged in untreated mice for 38 passages (once a week. a passage) which the parasites essentially reverted to normal sensitivity to artemether virtually. The Ieo of the RA line passage 63, 70. 85, 108 were <15, 16,<57,<58, respectively which were successively determined by crass-resistance to sodium artesunate, artemisinin, pyrimethamine and chloroquine. The I50 of the above 4 drugs were 15, 15. 0 and 16, respectively.