Canadian researchers to launch clinical trial to determine efficacy of treating latent TB with four-month course of Rifampin

Researchers at McGill University in Montreal on Tuesday announced they will soon launch an international clinical trial to determine if latent tuberculosis can be treated successfully with a four-month treatment course of the TB drug rifampin rather than the standard nine-month treatment with the TB drug isoniazid, the CP/Toronto Sun reports.

Nearly 6,000 people with latent TB from Australia, Benin, Brazil, Guinea, Saudi Arabia and South Korea, as well as five Canadian cities, will participate in the trial. Half of the participants will receive the standard nine-month treatment of isoniazid, while the other half will receive rifampin for four months. All of the participants will be followed for 28 months to determine how many develop active TB. Dick Menzies of McGill University, who is leading the trial, said the trial likely will take seven years to complete.

According to the CP/Sun, researchers believe the shorter course of treatment with rifampin could improve treatment compliance. In addition, although isoniazid is effective at treating latent TB, it can cause liver damage, the CP/Sun reports. Rifampin also can cause liver damage but does so less frequently than isoniazid, Menzies said.

Michael Gardam, director of the TB clinic at Toronto Western Hospital who was involved in a pilot study, said the clinical trial is "very much needed." Menzies added, "Four months of rifampin is, I would say, an increasingly popular option. But everyone is limited by the same problem, which is that we're unsure how well it works" (Branswell, CP/Toronto Sun, 3/23).