Effect of pirfenidone on pulmonary fibrosis due to paraquat poisoning in rats

Background. This study investigated the effectiveness of pirfenidone compared with antioxidants, in the prevention of pulmonary fibrosis and increasing the survival in acutely paraquat poisoned rats. Methods. Five groups of ten rats were included in this study. Three groups were poisoned with intraperitoneal injection of 15 mg/kg paraquat. Among these poisoned groups, one group was treated with vitamin C (500 mg/kg, intraperitoneal), vitamin E (200 mg/kg, intraperitoneal) and N-acetylcysteine (250 mg/kg, intravenous); two others were treated with either normal saline or pirfenidone (200 mg/kg, intravenous); two groups were not poisoned and received normal saline or pirfenidone (200 mg/kg, intravenous). All injections except paraquat were repeated in four consecutive days. On the 15th day of study a semi-quantitative determination of lung fibrosis was done using Ashcroft staging criteria on the lung sections. Results. Pirfenidone decreased paraquat induced lung fibrosis (p < 0.001) while antioxidants did not decrease the lung fibrosis (p = 0.413). Life expectancy decreased in paraquat + normal saline (11 days, 95% CI 7.94-14.05) and paraquat + antioxidant (11 days, 95% CI 7.77-14.23) groups. The increase in the survival of rats in paraquat/pirfenidone group was insignificant (13.4 days, 95% CI 11.13-15.67). Conclusion. This study showed that pirfenidone is able to decrease pulmonary fibrosis following paraquat poisoning in a rat model.