Assessment of toxicological effects of favipiravir (T‐705) on the lung tissue of rats: An experimental study

This study aimed to present new data on the side effects of favipiravir on healthy lung tissue and the respiratory system. In the study, two different durations (5 and 10 days) were preferred to determine the effect of favipiravir treatment due to clinical improvement rates of approximately 5 and 10 days during the use of favipiravir in COVID‐19 patients. In addition, after 10 days of favipiravir treatment, animals were kept for 5 days without any treatment to determine the regeneration of lung tissues. Favipiravir was administered to rats by oral gavage at a daily dose of 200 mg/kg for 5 and 10 days, as in previous studies. At the end of the experiment, the histopathological and biochemical effects of favipiravir in the lung tissue were investigated. The data obtained from the study showed that favipiravir increased oxidative stress parameters, expression of apoptotic markers, and pro‐inflammatory markers in lung tissue. Since malondialdehydes is an oxidant parameter, it increased in favipiravir‐administered groups; It was determined that the antioxidant parameters glutathione, superoxide dismutase, glutathione peroxidase, and catalase decreased. Other markers used in the analysis are Bcl‐2, Bax, NF‐κB, interleukin (IL)‐6, Muc1, iNOS, P2X7R, IL‐6 and caspase‐3. The levels of Bax, caspase‐3, NF‐κB, IL‐6, Muc1, and P2X7R were increased in the Fav‐treated groups compared with the control. However, the levels of Bcl‐2 decreased in the Fav‐treated groups. The present study proves that favipiravir, widely used today, causes side effects in lung tissue.