February 26, 2009

Combo May Treat Drug-Resistant TB

U.S. researchers said on Thursday that two existing drugs used in combination appear to offer great promise against the most dangerous form of tuberculosis, Reuters reported.

Doctors say the combination of AstraZeneca's MERREM I.V., also called meropenem, and clavulanate, sold by GlaxoSmithKline in combination with amoxicillin as the drug Augmentin, killed laboratory-grown strains of TB in clinical trials.

Researchers wrote in the journal Science that the combination worked in lab dishes against 13 extensively drug-resistant, or XDR, TB strains taken from patients with the complicated form of TB.

Death rates are high for those people with XDR-TB, as the aggressive TB type has few treatment options.

Experts say the numbers of cases of the infectious bacteria that defy standard tuberculosis drugs are increasing worldwide.

A clinical trial has been planned later this year using the drugs on about 100 XDR-TB patients in South Korea. Another clinical trial is planned in South Africa.

One of the researchers, John Blanchard of Albert Einstein College of Medicine of Yeshiva University in New York, said there are increasing numbers of cases of TB that are drug resistant, either multi-drug resistant (MDR) or extensively drug resistant (XDR), which are extremely difficult and costly to treat.

"There have been no drugs introduced in the chemotherapy of TB in 40 years. So this would be the first new class of compounds that could potentially be approved for the treatment of TB in the last 40 years. So that's exciting," he added.

MERREM I.V. is an intravenous antibiotic used against a variety of bacterial infections. Augmentin also is an antibiotic, although clavulanate by itself is not.

Clavulanate inhibits a bacterial enzyme that typically protects TB bacteria from meropenem, the researchers said. Both drugs are considered very safe and are approved by the U.S. Food and Drug Administration for adult and child use.

The U.N. World Health Organization said of the 9 million new TB cases reported annually, about 490,000 are MDR-TB and about 40,000 are XDR-TB, according to 2006 data.

Dr. Brian Currie of Albert Einstein College of Medicine, another of the researchers, said the study's results mean there is a tremendous potential for treating not only XDR-TB cases, but also routine TB cases.

Albert Einstein College of Medicine said it has filed a patent application for this TB treatment.


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