Objective To study the antimalarial activity of naphthoquine phosphate combined with artemisinine against Plasmodium knowlesi in rhesus monkey.Methods Monkeys were randomly divided into 9 groups(3/group).The monkeys in groups A and B were treated i.g.once daily for 3 days with 6 or 10 mg/kg of naphthoquine phosphate respectively.Those in groups C and D were treated i.g.twice for the 1st day and once for the 2nd and 3rd day with 31.6 or 100 mg/kg of artemisinine respectively.In groups E, F and G, they were treated i.g.only once with the combination of naphthoquine phosphate 10 mg/kg and artemisinine 10, 20 or 25 mg/kg respectively.Groups H and I served as controls which were treated i.g.only once with 10 mg/kg of naphthoquine phosphate and 30 mg/kg of artemisinine respectively.Parasitemia was examined beginning 24 h after drug administration.The observation lasted 105 days when no more parasite was found.Results At 24 h after drug administration, the parasite reduction rate in all groups was higher than 90%.The parasite clearance time for groups E, F and G was(56.0?16.0),(53.3?4.6), and(56.0?8.0) h respectively, more rapid than that of Group H(69.3?4.6) h.There were 1, 3, 3, 2, 2, and 3 monkeys in groups A, B, D, E, F, and G respectively which were cured.No monkeys were cured in groups C, H and I.Conclusion The combination of naphthoquine phosphate and artemisinine is superior to the single component and the optimum proportion in the combination is 1:2.5 in treating P.knowlesi infection in monkeys.

Objective To compare the efficacy and safety of naphthoquine, artemisinine and a combination of the two drugs in the treatment of faciparum malaria. Methods Of 230 patients, 100 patients were treated with combined regime (Co-NQ), 100 patients were treated with naphthoquine (NQ) and 30 patients were treated with artemisinine (QHS). All patients were hospitalized for 7 days and followed up for 28 days. Results The mean fever clearance time for Co-NQ, NQ, and QHS was (17.5 ?12.3)h, (32.7?17.7)h and (18.1?9.7)h respectively; the mean parasite clearance time was (30.0?8. 8)h,(45.5?10.0)h and (29.1?6.0)h respectively; and the 28 days cure rate was 97.0% ,100.0% and 66.7% respectively. Conclusion The Co-NQ possesses benefits of both naphthoquine and artemisinine, acting rapidly, with a short course of only one dose and a high cure rate. The regime is well tolerated by patients.