New, Antimalarial, Tricyclic 1,2,4-Trioxanes: Evaluations in Mice and Monkeys

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  • Department of Chemistry, The Johns Hopkins University, Division of Experimental Therapeutics, Walter Reed Army Institute of Research, Center for Tropical Parasitic Diseases, University of Miami School of Medicine, Gorgas Memorial Laboratory, Baltimore, Maryland, Panama

We have concluded initial preclinical studies with synthetic trioxanes numbered 3–9 and have compared them with artemisinin (numbered 1) using CD-1 mice infected with Plasmodium berghei. Based on their antimalarial effectiveness in mice, two of these synthetic trioxanes were selected for evaluation in Aotus monkeys infected with multidrug-resistant (MDR) P. falciparum. Trioxane numbered 8 (12 and 48 mg/kg), trioxane numbered 9 (12 and 48 mg/kg) and arteether (numbered 2, 48 mg/kg) were administered intramuscularly in three 12-hr doses to A. lemurinus lemurinus (Panamanian owl monkeys) infected with the Vietnam Smith/RE strain of P. falciparum and monitored for parasitemia. Trioxane numbered 8 at 12 mg/kg cleared parasitemia in two monkeys, but recrudescence occurred in one animal. Treatment of the recrudescent infection with 48 mg/kg was curative. Infections in two monkeys treated initially with 48 mg/kg were cured (six-month follow-up). Trioxane numbered 9 produced a similar outcome: 12 mg/kg suppressed parasitemia in two monkeys but was not curative; however, 48 mg/kg cured infections in all four monkeys treated. These preliminary observations show synthetic trioxanes numbered 8 and 9 to be as effective as arteether (numbered 2) against MDR in P. falciparum in the Aotus monkey.