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Little Research on Diseases Affecting the Poor

by Medindia Content Team on  January 10, 2008 at 11:22 AM General Health News   - G J E 4
Little Research on Diseases Affecting the Poor
Westerners evince little interest in research on diseases afflicting the poor in remote lands, say as in the case of the African sleeping sickness.
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Last month, the Bill and Melinda Gates Foundation donated $19 million to the Drugs for Neglected Diseases Initiative, the African sleeping sickness being a priority area.

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But then, even if a miracle cure is found, it will take lab work and clinical trials that could easily cost $100 million.

'Sleeping sickness' is too benign a nickname for human African trypanosomiasis, which is caused by a protozoan spread by biting tsetse flies. When the parasites enter the brain, victims hallucinate wildly. They have been known to chase neighbors with machetes, throw themselves into latrines and scream with pain at the touch of water. Only at the end do they lapse into a lassitude so great that they cannot eat, followed by coma and death.

About 150,000 people contract the disease each year, but 50 million people in 36 countries live in areas where they are at risk.

The plan for sleeping sickness is a series of incremental steps, said Dr. Bernard Pécoul, a former member of Doctors Without Borders who founded the partnership in 2003, reports The New York Times.

A drug started from scratch might not be ready till 2020 or later. A perfect one, he said, would be taken orally, would cure the disease in less than a week and would have no horrible side effects. But until then, even slight advances in treatment will benefit victims, who now face choices familiar to cancer patients: the cure is so rough that the only thing worse is no cure.

The best treatment now is eflornithine, sometimes called the resurrection drug because it can pull the dying out of comas.

It is almost a miracle that eflornithine is available. It was discovered in 1980 at Pace University in New York. By early 2000, the last 7,500 doses in the world were running out. The patent-holder, a precursor of the drug maker Sanofi-Aventis, abandoned it in 1995 because it had not lived up to its anticancer potential. Then, in late 2000, plans to make a topical form emerged. It was the key ingredient in Vaniqa, a cream to prevent facial hair in women.

After critics accused Sanofi-Aventis of catering to vain rich women while letting poor Africans die, the company agreed to make an injectable form of the drug and now gives it free to the World Health Organization and Doctors Without Borders.

But in rural Africa, eflornithine is very hard to use. Patients need intravenous infusions four times a day for two weeks. When a 'hospital' is a row of iron beds under a thatched roof, and the 'nursing staff' is mostly relatives of the sick who sleep on the floor, round-the-clock treatment is hard. There might be no night nurse to insert an IV line.

For that reason, many countries do not adopt it. They still use the drug melarsoprol, which, Dr. Pécoul said, 'is not effective and sometimes kills.'

Melarsoprol, invented in the 1940s, is essentially arsenic dissolved in propylene glycol, the antifreeze ingredient. It can be given once a day for 10 days, which is easier on nurses. But it kills 5 percent of those who take it and burns survivors' veins.

Dr. Pécoul hopes to have more countries switch to a mix of seven days of eflornithine twice a day — so that night nurses are not needed — plus seven days of nifurtimox, an oral drug that kills protozoa but is ineffective alone. To do that, he hopes by next year to be able to report favorable results from clinical trials under way at six sites in Uganda, Congo and the Congo Republic, and then persuade the W.H.O. to recommend the regimen.

By 2014, he hopes to have evidence that another drug, fexinidazole, is better. It can be taken orally, and in animal tests it cures even late-stage sleeping sickness in the brain within two weeks. But it has not been tested on humans. Phase 1 trials, small tests of its safety in humans, are to start late this year.

Fexinidazole was developed by the German pharmaceutical company Hoechst, now part of Sanofi-Aventis, and abandoned in the 1980s when the company gave up its tropical disease programs, said Els Torreele, who directs the initiative's fexinidazole project. It is one of a class of drugs known as azoles, like fluconazole, that work against fungi and may work against cancer.

'We tested 500 different azoles,' Dr. Pécoul said. The advantage of adopting an abandoned drug is that the former patent-holder has usually done the chemical analyses, animal studies and, sometimes, early human trials, saving millions of dollars.

The $19 million from the Gates Foundation is not for that, but to begin the hunt for a completely new candidate. Yves J. Ribeill, founder of Scynexis, a North Carolina drug company that will receive much of the grant, said his chemists would fill legions of tiny test tubes with parasites swimming in calf serum, and legions more with mammalian tissue cells, and dose them all with thousands of molecules from chemical 'libraries.' Dr. Pécoul's group has negotiated deals to use about 20 university and drug company libraries.

After gathering 'hits' — compounds that kill parasites but not cells — Scynexis has to work out ways to make them into 'leads,' which are versions that are potent, safe and easy to make, and will 'last long enough in the blood to have an effect and then disappear,' Dr. Ribeill said.

Then trials begin, first in mice, then in other animals and finally in humans. Each will take years and will need further grants like the latest from the Gates Foundation.

Source: Medindia
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