Clinical experience and adverse drug events of favipiravir use in real-world data, Thailand

Favipiravir is one of the antiviral agents for coronavirus disease 2019 (COVID-19). This study described the adverse drug events (ADEs) and factors associated with aspartate transaminase (AST) or alanine transaminase (ALT) elevation in Thai COVID-19 patients who received favipiravir. A cross-sectional study was conducted at King Chulalongkorn Memorial Hospital, Thailand, among patients aged 18 years old or over with confirmed COVID-19, admitted between April and June 2021, and received favipiravir for COVID-19 treatment. Clinical pharmacists followed up ADEs after discharge from the hospital by phone. Seven hundred and fifteen COVID-19 patients were included in the study. Pharmacists could complete follow-ups on ADEs for 543 (75.9%) patients and 158 (29.1%) patients had ADEs. Constipation was the most common ADEs (30.38%). From multivariate analysis, taking psychiatric drug was associated with elevation of AST or ALT more than 3 times from baseline laboratory values (odds ratio = 13.866, P = 0.01). Three (0.4%) patients stopped favipiravir treatment because of drug-induced hepatitis. Eight of nine patients who used warfarin had international normalized ratio (INR) elevation. In conclusion, favipiravir is a safe drug. Closed laboratory monitoring might not be needed, except for liver function tests in patients who take psychiatric drugs and close INR monitoring in patients who receive warfarin coadministration.