New treatment option for latent tuberculosis

January 22, 2009

Patients who are infected with the latent form of tuberculosis (TB) show no symptoms and are not contagious, yet they pose the biggest challenge when it comes to controlling the disease. The latest study by Dr. Dick Menzies of the Research Institute of the McGill University Health Centre (MUHC) describes a new potential treatment for this particular form of TB. The paper based on this study was recently published in the Annals of Internal Medicine.

"Our results show that a four-month treatment with a drug called rifampin is better tolerated than the traditional nine-month treatment with a drug called isoniazid," explained Dr. Menzies. "The side effects with rifampin are much less frequent, particularly liver toxicity - which is the most serious risk of the traditional therapy with isoniazid. In addition patients are much more likely to complete this treatment - another big drawback to the nine month standard therapy."

Patients who currently receive a diagnosis of latent TB are treated for nine months with daily doses of isoniazid. Although effective, this treatment is very long and has major side effects on the liver. It is therefore common that patients do not complete treatment. Of course, this reduces the treatment's efficacy.

The new therapeutic option studied by Dr. Menzies lasts only four months and causes a lot less liver damage. Patients therefore adhere better to their treatment regimens, which is a critical first step towards ensuring the efficacy of the medication. This study was conducted on 847 patients in Canada, Brazil and Saudi Arabia. The results can therefore be generalized to a very broad population.

Currently, rifampin is most often used to treat the active form of TB. More in-depth studies will be necessary to test the effectiveness of this medication against latent TB, but the study researchers consider this treatment option to be very promising.

This study was funded by the Canadian Institutes of Health Research (CIHR) and the Fonds de la recherche en santé du Québec (FRSQ).

Dr. Dick Menzies is the Director of Respiratory Medicine at the MUHC and a researcher in the Respiratory Health Axis and Health Outcomes Axis at the Research Institute of the MUHC. He is also a Professor in Medicine, Epidemiology and Biostatistics - in the Faculty of Medicine of McGill University.

Source: McGill University Health Centre