Sleeping sickness pill may work as well as injections

From Philadelphia, at a meeting of the American Society of Tropical Medicine and Hygiene

An orally delivered drug for treatment of sleeping sickness is demonstrating considerable effectiveness in its first large-scale test in Africa.

Researchers used blood tests obtained at clinics in the Democratic Republic of the Congo, Angola, and Sudan to identify 273 people who had the West African version of sleeping sickness. The scientists then randomly assigned half of these people to get a 10-day course of pafuramidine maleate pills and half to receive daily injections of a standard sleeping sickness drug, pentamidine, for 1 week. The participants were recruited and treated between August 2005 and March 2007.

Interim results show that only 18 people have gotten worse despite being treated. One of these people died after refusing additional treatment, says Carol A. Olson, a biochemist at Immtech Pharmaceuticals of Vernon Hills, Ill., which teamed with a consortium of research institutions led by the University of North Carolina at Chapel Hill.

While it remains unclear whether one drug is outperforming the other, the low relapse rate suggests both are working, Olson says. “Ostensibly, [the patients who haven’t relapsed] are doing as well or better than they were” at the outset of treatment, she says.

Having an effective sleeping sickness drug that doesn’t need to be injected would be a first, Olson says.

Sleeping sickness is caused by the protozoan Trypanosoma brucei, which is spread by the bite of the tsetse fly. The parasite resides in the blood and lymph tissues. Laboratory tests had established that pafuramidine maleate can kill it, although how it does so isn’t fully understood.

The drug seems to target this parasite specifically, without harming the infected person. It might work against the T. brucei variation that causes the more virulent East African sleeping sickness and might also kill the parasite responsible for Chagas disease, Trypanosoma cruzi, Olson says.

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