Activation of Paludrine in vitro

Abstract

PALUDRINE has recently been introduced into clinical medicine as a drug which is highly active against most species of malaria parasite ; its formula is Tonkin¹, in this laboratory, investigated its effect on the exoerythrocytic forms of P. gallinaceum grown in tissue culture, and found that it had no action upon the parasites in the highest concentrations (2–5 mgm. per litre) tolerated by the macrophages. Since this concentration is many times greater than that which is believed to be present in the plasma in human therapy (probably about 0.3 mgm. per litre) its inactivity was surprising ; and the action of paludrine in vitro has been investigated further using P. cynomolgi of monkeys, and the exoerythrocytic forms of P. gallinaceum grown in tissue culture, as test organisms. P. cynomolgi was cultured in vitro at 37° C. by a modification of Bass and John's technique and, 41 hours later, smears were made and stained with Giemsa. The parasites found were classified according to the number of pieces of chromatin present, and the resulting differential counts are shown in the accompanying table. The figures indicate the percentage of parasites containing 1, 2–3, 4–5 pieces of chromatin, etc., respectively.