IC50: 0.1-5.2 nM for various P. falciparum strains [1]
Malaria remains a disease of devastating global impact, killing more than 800,000 people every year-the vast majority being children under the age of 5. Naphthoquine phosphate is a antimalarial drug developed in China.
In vitro: Naphthoquine phosphate showed promising antimalaria acitivities against various P. falciparum strains. Moreover, previoius study highlighted that naphthoquine did not lose potency when tested against chloroquine resistant strains [1].
In vivo: In an study aiming to investigate the antimalarial activity of naphthoquine phosphate combined with artemisinine against Plasmodium knowlesi in rhesus monkey, it was found that the combination of naphthoquine phosphate and artemisinine was superior to the single component and the optimum proportion in the combination is 1 : 2.5 in treating P. knowlesi infection in monkeys [2].
Clinical trial: An oral single dose of the combination drug (400 mg of naphthoquine + 1000mg artemisinin) was administered to adult uncomplicated falciparum malaria patients. Mean fever clearance time, parasite clearance time were 18.2 ± 8.6 h and 34.6 ± 14.3 h, respectively. Adequate clinical and parasitological response was achieved in 52 out of 54 cases, the rate being 98.1%. The drug was well tolerated and no adverse reactionswere detected in the patients [3].
References:
[1] Delves M, Plouffe D, Scheurer C, Meister S, Wittlin S, Winzeler EA, Sinden RE, Leroy D. The activities of current antimalarial drugs on the life cycle stages of Plasmodium: a comparative study with human and rodent parasites. PLoS Med. 2012;9(2):e1001169.
[2] Wang JY, Ding DB, Li GF, Zhao JH. Therapeutic efficacy of naphthoquine phosphate combined with artemisinine against Plasmodium knowlesi. Zhongguo Ji Sheng Chong Xue Yu Ji Sheng Chong Bing Za Zhi. 2008;26(6):442-4.
[3] Tun T, Tint HS, Lin K, Kyaw TT, Myint MK, Khaing W, Tun ZW. Efficacy of oral single dose therapy with artemisinin-naphthoquine phosphate in uncomplicated falciparum malaria. Acta Trop. 2009;111(3):275-8.