Four hundred and twenty-six patients had 859 episodes of malaria due to Plasmodium falciparum in late 1965. An analysis of the results of therapy reveals the following data: chloroquine was successful as treatment in 11% of the cases, quinine in 50%, chloroquine and quinine in 35%, pyrimethamine in 91%, quinine and pyrimethamine in 95%, and all three drugs combined in 80% Quinine alone was more effective, when used for 13 days or longer, than when used for 12 days or less. Chloroquine had a dose-related inhibitory effect on the success rate when combined with quinine. The best combination used was quinine and pyrimethamine.
William, P. Reed, Michael Feinstein, Barry W. Steiger. Early Experiences in the Treatment of Falciparum Malaria From Southeast Asia. JAMA. 1968;205(3):131–133. doi:10.1001/jama.1968.03140290023006