THE TOXICITY OF TETRAHYDROHOMOFOLIC ACID IN NORMAL AND MALARIA-INFECTED MONKEYS

¹ Department of Pharmacology, Tufts University School of Medicine, Boston, Massachusetts, and National Center for Primate Biology, University of California, Davis, California

Intravenous administration of sodium tetrahydrohomofolate to Macaca mulatta (rhesus monkeys) led to anorexia, diarrhea, impaired renal function, leukopenia and reticulocytopenia. None of these toxic signs was seen when tetrahydrofolate was administered concurrently. Delayed administration of tetrahydrofolate blocked the leukopenia and diminished the duration of the other toxic signs. Intravenously administered tetrahydrohomofolate is largely excreted in the urine. When administered orally very low blood levels were attained. In spite of its lability toward oxygen, tetrahydrohomofolate is relatively stable in circulating blood. The compound did not modify the course of infections with Plasmodium cynomolgi in the rhesus monkey.