Isoniazid is used as a first-line drug for the treatment of tuberculosis in combination with other drugs. Long-term use of isoniazid has been known to cause liver toxicity. Some drugs have been approved to treat the isoniazid induced side effects. The purpose of the current study was to evaluate hepatoprotective effect of pyridoxine and compare it with N-acetylcysteine alone or in combination, in isoniazid-induced liver toxicity. The study was carried out on 30 Wistar rats equally divided into 5 groups. Isoniazid at 50 mg/kg dose was used to induce hepatotoxicity in rats. Pyridoxine (50 mg/kg) and N-acetylcysteine (100 mg/kg), either alone or in combination, were orally administered for four weeks. Body weight was checked weekly. After receiving N-acetylcysteine and pyridoxine, blood and liver tissues were collected for biochemical analysis and histological findings. The biochemical analysis included alanine transaminase, aspartate aminotransferase, total bilirubin, and hepatic glutathione levels. Rats treated with N-acetylcysteine and pyridoxine, in combination, showed significant changes in the level of various liver enzymes and hepatic glutathione. Conversely, as compared to the positive control group, in rats treated with N-acetylcysteine and pyridoxine alone, the effect of N-acetylcysteine was found more than pyridoxine. In conclusion, pyridoxine can be used as a hepatoprotective drug in isoniazid induced hepatotoxicity, either alone or in combination with N-acetylcysteine. Both pyridoxine and N-acetylcysteine possess positive effect on glutathione level.

Keywords: Drug induced liver injury, hepatotoxicity, isoniazid, N-acetylcysteine, pyridoxine