Abstract:
10 to 30 days to facilitate treatment with parenterally administered medicines. The efficacy of a novel
orally administered prodrug, 2,5-bis(4-amidinophenyl)-furan-bis-O-methlylamidoxime (pafuramidine,
DB289), was tested in the vervet monkey (Chlorocebus [Cercopithecus] aethiops) model of sleeping sickness.
Five groups of three animals each were infected intravenously with 104 Trypanosoma brucei rhodesiense
KETRI 2537 cells. On the seventh day postinfection (p.i.) in an early-stage infection, animals in groups
1, 2, and 3 were treated orally with pafuramidine at dose rates of 1, 3, or 10 mg/kg of body weight,
respectively, for five consecutive days. The animals in groups 4 and 5 were treated with 10 mg/kg for 10
consecutive days starting on the 14th day p.i. (group 4) or on the 28th day p.i. (group 5), when these
animals were in the late stage of the disease. In the groups treated in the early stage, 10 mg/kg of
pafuramidine completely cured all three monkeys, whereas lower doses of 3 mg/kg and 1 mg/kg cured only
one of three and zero of three monkeys, respectively. Treatment of late-stage infections resulted in cure
rates of one of three (group 4) and zero of three (group 5) monkeys. These studies demonstrated that
pafuramidine was orally active in monkeys with early-stage T. brucei rhodesiense infections at dose rates
above 3 mg/kg for 5 days. It was also evident that the drug attained only minimal efficacy against late-stage
infections, indicating the limited ability of the molecule to cross the blood-brain barrier. This study has
shown that oral diamidines have potential for the treatment of early-stage sleeping sickness.
