The sterilizing value of rifampicin and pyrazinamide in experimental short course chemotherapy

Besides the long-term effectiveness of a given compound, safety is a very important feature to consider when developing new compounds for chemotherapy against tuberculosis. Reports of fatal and severe liver injury associated with rifampicin–pyrazinamide (RIF-PZA) treatment regimens for latent tuberculosis infections prompted this study to evaluate whether a mouse model has any potential as a tool to assess liver injury following extensive exposure to tuberculosis drugs. Mice were administered high doses of existing drug regimens for latent tuberculosis over a relatively short time period. Alanine aminotransferase (ALT), aspartate aminotransferase and bilirubin levels were determined after 2 weeks and 4 weeks of treatment in serum samples collected from uninfected mice as well as mice infected with Mycobacterium tuberculosis. ALT levels increased significantly after a RIF-PZA treatment regimen for 4 weeks in uninfected mice and after 2 weeks in infected mice. Bilirubin serum levels were also significantly elevated in the M. tuberculosis-infected mice after 4 weeks of RIF-PZA treatment. The data obtained indicate that changes in serum enzyme levels in mice after extensive exposure to tuberculosis drugs could be useful as an initial indicator of drug-related hepatotoxicity.