An Evaluation of Antimalarial Combinations against Plasmodium berghei in the Mouse

Abstract

The suppressive action of various doses of chloroquine, amodiaquine, primaquine and pyrimethamine on the development of parasitemia in mice infected with P. berghei was investigated. After the dose-suppression curve was established for each of the four drugs, various combinations of two and three drugs were compared with equivalent doses of single drugs. Test mice were infected intravenously with 1 million parasitized red blood cells. Drugs were administered by stomach tube daily for 5 consecutive days, beginning on the day of infection (day 0). Parasitemia was evaluated from blood smears made on day 6 of infection. Average per cent parasitemia for animals within test groups was used to compare the effect of various drug treatments. By the test procedure employed, combinations of chloroquine, amodiaquine, primaquine, and pyrimethamine were not superior to single drug treatments in suppression of the development of parasitemia in mice infected with P. berghei. The joint suppressive action of combinations of two or three of these drugs was additive, or less than additive, and no evidence of synergism was observed.