Xanthine oxidase inhibition by allopurinol increases in vitro pyrazinamide-induced hepatotoxicity in HepG2 cells.

Despite the important role of pyrazinamide in tuberculosis treatment, little is known about the mechanism of pyrazinamide-induced hepatotoxicity. We inhibited xanthine oxidase in HepG2 cells by using a nontoxic concentration of allopurinol, a well-known xanthine-oxidase inhibitor. This increased in vitro pyrazinamide toxicity in HepG2 cells, which suggests that the hydroxy metabolites of pyrazinamide are probably not fully responsible for pyrazinamide-induced toxicity, and that pyrazinoic acid and pyrazinamide are involved in pyrazinamide toxicity.