Comparison of the curative antimalarial activities and toxicities of primaquine and its d and l isomers.
This investigation was undertaken to determine whether either d-primaquine or l-primaquine has sufficient advantage over primaquine to warrant evaluation for curative activity in human volunteers infected with Plasmodium vivax. It was found: (i) that the capacities of the isomers and the racemate to cure infections with Plasmodium cynomolgi in rhesus monkeys were essentially identical; (ii) that the subacute toxicities of the isomers and racemate for this monkey were qualitatively the same, but that l-primaquine was three to five times as toxic as d-primaquine and at least twice as toxic as primaquine; and (iii) that the acute single-dose toxicities of the isomers for mice were not only qualitatively different, but that the d isomer was at least four times as toxic as l-primaquine. Since previous appraisals of curative activity and tolerability of 8-aminoquinolines in rhesus monkeys have correlated well with appraisals in human volunteers, attention was focused on results acquired with these test subjects. The relevant evaluations showed that d-primaquine had a therapeutic index at least twice that of primaquine. If this advantage carries over to man, problems that now complicate routine use of primaquine might be obviated. Therefore, a critical comparison of d-primaquine and primaquine in human volunteers seems indicated.
D000818:Animals; D005260:Female; D000882:Haplorhini; D007928:Lethal Dose 50; D008253:Macaca mulatta; D008288:Malaria / Q000188:drug therapy*; D008297:Male; D051379:Mice; D011319:Primaquine / Q000009:adverse effects / Q000627:therapeutic use* / Q000633:toxicity; D013237:Stereoisomerism; D013997:Time Factors
D011319:Primaquine