A Comparison of the Antimalarial Effects of Suppressive Doses of Chloroquine, Amodiaquin, and Pyrimethamine

Max J. MillerThe Liberian Institute of the American Foundation for Tropical Medicine, Harbel, Liberia

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Summary and Conclusions

The antimalarial effects of chloroquine (Aralen), amodiaquin (Camoquin) and pyrimethamine (Daraprim) were tested respectively in three groups of African school children; a fourth group served as control. A total of 148 children were studied over a period of 12 weeks. All drugs were administered at weekly intervals in the following dosages: Chloroquine (base) 0.15 gm., amodiaquin 0.2 gm., pyrimethamine 12.5 mgm.; children in the control group received placebos. Blood smears for parasite rate studies were examined prior to and at weekly intervals during the course of the experiment. Spleen surveys were made before and at 4-weekly intervals during the course of the experiment. At no time was there evidence of drug intolerance.

The results of parasite rate studies clearly indicate that in the dosages used all three drugs are highly efficient in clearing the blood of asexual malaria parasites. Chloroquine showed the most rapid action, and although pyrimethamine took somewhat longer to exert its effect it was equally effective in eliminating parasites from the blood. Amodiaquin did not prove to be quite as effective and in several children a temporary “break-through” did occur.

The gametocyte rate showed an early transient rise only in children receiving pyrimethamine, an observation also made by Foy and Kondi (1952). However, there was a definite decrease in the gametocyte rate in all three groups receiving antimalarials after several weeks of drug administration.

By the end of the 12-week treatment period the children in the three groups receiving the antimalarials showed an equally marked regression in both the spleen rates and the average enlarged spleen. The initial spleen reduction appeared to be somewhat more rapid in children receiving amodiaquin.