TIME DOSE-RESPONSE OF TRYPANOSOMA-CONGOLENSE BLOOD-STREAM FORMS TO DIMINAZENE AND ISOMETAMIDIUM

Trypanosoma congolense bloodstream forms were propagated in vitro axenically in a simplified cultivation medium at 34-degrees-C. Viability of a drug-sensitive and a drug-resistant clone were examined for 10 days following exposure to 0.1, 1.0 and 10.0 mug ml-1 of diminazene aceturate and 0.1, 1.0 and 10.0 ng ml-1 of isometamidium chloride for various time intervals. Drug-sensitive T. congolense were irreversibly damaged after incubation with 10 mug ml-1 or 1 mug ml-1 diminazene aceturate for 30 min or 2 h, respectively, while drug-resistant trypanosomes were not affected. Exposure to 10 ng ml-1 isometamidium chloride eliminated drug-sensitive trypanosomes after 24 h and drug-resistant trypanosomes after 96 h. The data obtained on in vitro time-dose responses of T. congolense were related to pharmacokinetic data of diminazene and isometamidium in cattle plasma.