Nearly 1 in 10 Failure Rate Could Accelerate Spread of Drug Resistance

In the largest ever study of its kind, new research shows that substandard and falsified tuberculosis medicines are widely used and likely contribute to the rise in drug-resistant strains of the disease.

Researchers tested 716 samples of two tuberculosis medicines, isoniazid and rifampicin, which comprise a standard TB treatment regimen. The samples were purchased from pharmacies in 17 countries across Africa, Asia, Europe and Latin America.

Across all countries, 9.1 percent of samples were substandard or falsified. In African countries, one in six samples-16.6 percent-were substandard or falsified.

"Record numbers of people are contracting drug-resistant TB, and those numbers are rising worldwide. We don't understand the extent to which poor quality drugs are contributing to this epidemic, nor has it been a policy priority to figure it out," said Dr. Roger Bate, Resident Scholar at the American Enterprise Institute and lead author on the study. "Our data represent conservative estimates and should sound a warning to public health officials. If we don't address the issue of drug quality, particularly in India, China and African countries where the rates of TB drug resistance are accelerating, years of progress against the disease could be undone."

The medicine samples were tested for levels of active pharmaceutical ingredient-the molecule that acts against the TB bacteria. Samples were considered failures if they lacked acceptable levels of active ingredient.

Of the failing samples, 55.4 percent contained significant amounts of active ingredient, but less than the amount required to make the drug effective. The remaining 44.6 percent of failing samples contained very little or no active ingredient. Both types of failing drugs can cause drug-resistance to develop.

"As tuberculosis becomes resistant to isoniazid and rifampicin, it becomes deadlier and vastly more expensive to control," said Paul Martin Jensen, a coauthor on the study and a member of the Stop TB Partnership's Advocacy and Communications Core Group. "It costs about $250,000 to treat one person for multidrug-resistant TB in the U.S., and states are reporting shortages of the drugs they need to treat current patients. As TB drug-resistance grows worldwide, we must prepare to face the future of this disease."

The study was published today in the February issue of the International Journal of Tuberculosis and Lung Disease. The authors encouraged public health and development agencies to conduct further research into the quality of TB medicines and its relationship with rates of drug resistance.

"CDC, USAID, the U.S. State Department and World Bank should urgently put this issue on the public health agenda. As long as substandard tuberculosis drugs are permitted in the marketplace, people will die in pursuit of a cure. And without a coordinated response, growing resistance will eventually render even the highest quality drugs obsolete," Bate concluded.

The World Health Organization estimates that there were 8.7 million new cases of infectious tuberculosis and 1.4 million TB deaths in 2011. Of the total cases, WHO estimates that 640,000 were new cases of multidrug-resistant TB, defined as resistance to at least isoniazid and rifampicin-the two drugs analyzed in this study.

Drug samples were collected and tested from pharmacies in the following countries: Angola, Brazil, China, the Democratic Republic of the Congo, Egypt, Ethiopia, Ghana, India, Kenya, Nigeria, Russia, Rwanda, Thailand, Turkey, Uganda, the United Republic of Tanzania, and Zambia.