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  • Common antibiotic could help cut TB deaths

A safe, cheap and widely available antibiotic could help prevent deaths from tuberculosis (TB), according to researchers.

Doxycycline has been used as an antibiotic since the 1960s to treat a range of bacterial infections, and has more recently also been suggested as a possible treatment for river blindness and lymphatic filariasis (elephantiasis).

Now, a study published in the American Journal of Respiratory and Critical Care Medicine last month (16 February), says it could also be useful in treating TB, by protecting against lung damage and hampering the growth of TB bacteria.

TB increases the production of an enzyme called MMP-1 in humans, which damages lung tissue. Reducing the production of this enzyme could reduce the number of deaths from TB, the authors said. Laboratory tests showed that doxycycline inhibits MMP-1 enzyme production by human cells. In animal models it also reduced TB bacteria growth.

"We have sufficient evidence that [it] might be beneficial to proceed to clinical trials in humans," said Paul Elkington, lead author of the study and a researcher at Imperial College London, in Britain. He is seeking funding to conduct clinical trials in developing countries in which TB is most acute.

Elkington said if the trials are successful, doxycycline could be used in combination with existing TB treatments or as a good second line drug to treat multi-drug-resistant TB, noting that most of the existing MDR drugs are expensive and toxic whereas doxycycline is cheap and safe.

Bertel Squire, professor of clinical tropical medicine at the Liverpool School of Tropical Medicine, United Kingdom, said it would be a challenge to obtain sufficient funding and support to add doxycycline to existing regimes.  

"The main benefit would be its possible effect in reducing tissue damage," said Squire. "The anti-TB effect would be a spin-off benefit and might hasten clearance of the bugs."

But "existing first-line TB regimens for drug-sensitive disease are so effective that it will take very large numbers of patients in huge trials to have sufficient [statistical evidence] to demonstrate any additive effect of doxycycline to existing regimens," Squire told SciDev.Net.

References

American Journal of Respiratory and Critical Care Medicine doi: 10.1164/rccm.201110-1769 (2012)