For the past 50 years, the development of new drugs to treat tropical diseases that affect nearly one billion people has languished because it has not been profitable for drug manufacturers in the West. But that could change with a so-called voucher program that will give U.S. drug manufacturers a major financial incentive to develop drugs for illnesses that are rarely seen in developed countries. VOA's Jessica Berman reports.

Last year, U.S. drug makers were handed what some say could be a huge financial benefit.

The U.S. Congress gave the Food and Drug Administration permission to issue what it calls a voucher to any pharmaceutical company that is granted regulatory approval for a new tropical medicine.

The list of eligible diseases includes tuberculosis, malaria, and schistosomiasis along with other illnesses caused by worms and parasites.

The voucher will give a manufacturer expedited consideration of any experimental medicine that the company believes could become what is known in the industry as a "blockbuster" drug. Previous blockbusters include Viagra for erectile dysfunction and Prozac for the treatment of depression.

Timothy Cote is director of the FDA's office that oversees the approval of products for diseases affecting less than 200,000 people in the United States.

"Drug sales for [a] typical blockbuster can extend between $3 billion and $10 billion to $12 billion, that's with a 'b,' billion dollars per year in sales," Cote. "So, making it faster to review those has a financial value if you have $5 billion in sales and you can speed the review process up by six months, well that's $2.5 billion, which is a lot of money."

The average review process by the FDA takes between 10 and 18 months. Under the voucher program, the U.S. regulatory agency will consider applications seeking approval for blockbuster drugs within six months.

Cote says the expedited review in no way compromises safety.

"It doesn't change the review," he said. "It doesn't guarantee an approval. It only says that we will speed review of some other drug. Now, this voucher will only be most useful for blockbuster drugs that have large market potential in the future."

Despite such guarantees, Harvard University Medical School professor Aaron Kesselheim thinks racing to develop drugs for tropical illnesses in order to get a voucher is a bad idea.

Kesselheim points to a just-released study by colleagues at Harvard which found that U.S. regulators, feeling the pressure to approve new drugs in a shorter time frame, approved medications that were five times more likely to be withdrawn from the market for safety reasons.

The researchers also found that more than four percent of new drugs that found their way to consumers had to have a stern, black box safety warning added to the packaging.

Kesselheim says the financial lure of a voucher may attract companies with no experience in developing drugs for tropical diseases.

"A company that might be really good at making cardiovascular medications is going to try to get faster reviews to enter the tropical disease development world and might not be as skilled as other manufacturers who might be focused on anti-infective products," said Kesselheim.

James Geraghty is Senior Vice President of Genzyme Corporation, a biotechnology firm that develops new drugs and stands to benefit from the voucher program.

Geraghty says the FDA's program will not compromise the safety standards of the drug manufacturing industry.

"Expedited review does not involve, we don't ever intend it to involve, any lowering of standards," he said. "It's just a prioritization system that provides for prioritization and acceleration of review for important public health reasons, not in any way a reducing of the standards of that review."

Harvard's Kesselheim thinks there are better ways to encourage the development of new drugs for neglected diseases, including front end commitments from developing countries to Western drug makers to purchase large quantities of tropical medicines once they are developed.

The voucher program is scheduled to take effect in September.