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J Virus Erad. 2020 Apr 30;6(2):45-51.
A review of the safety of favipiravir - a potential treatment in the COVID-19 pandemic?
Pilkington V1,2, Pepperrell T1,2, Hill A2,3.
Author information
Abstract
Background:
Repurposing broad-spectrum antivirals is an immediate treatment opportunity for 2019 coronavirus disease (COVID-19). Favipiravir is an antiviral previously indicated for influenza and Ebola, which has shown some promise in early trials for treatment of COVID-19. We aim to review existing favipiravir safety evidence, which is vital to informing the potential future use of favipiravir in COVID-19.
Methods:
A search was conducted across EMBASE and MEDLINE databases, supplemented by relevant grey-literature and ClinicalTrials.gov. All studies assessing the use of favipiravir in humans by 27 March 2020 were considered for inclusion. Further analysis of available safety data from phase 2 and 3 studies was undertaken. Data extracted were adverse events (AEs) grade 1-4, serious AEs and discontinuation for AEs. Specific AEs of interest highlighted in early-phase studies, including gastrointestinal AEs and hyperuricaemia, were also examined.
Results:
Twenty-nine studies were identified as potential sources of evidence of the clinical safety of favipiravir. Six were phase 2 and 3 studies reporting relevant safety data for statistical comparison, representing a total of 4299 participants, an estimated 175 person-years-of-follow-up (PYFU). Comparator drugs were oseltamivir, umifenovir, lopinavir/ritonavir or placebo. Study follow-up was between 5 and 21 days. The proportions of grade 1-4 AEs on favipiravir was 28.2% vs 28.4% (P = n.s.) in the comparison arms. The proportion of discontinuations due to AEs on favipiravir was 1.1% vs 1.2% (P = n.s.) in the comparison arms. For serious AEs the proportion was 0.4% in both arms (P = n.s.). There were significantly fewer gastrointestinal AEs occurring on favipiravir vs comparators [8.7% vs 11.5%; P = 0.003]. Favipiravir showed significantly more uric acid elevations than comparators [5.8% vs 1.3%; P<0.0001].
Conclusions:
Favipiravir demonstrates a favourable safety profile regarding total and serious AEs. However, safety concerns remain: hyperuricaemia, teratogenicity and QTc prolongation have not yet been adequately studied. Favipiravir may be safe and tolerable in short-term use, but more evidence is needed to assess the longer-term effects of treatment. Given the limitations of the evidence and unresolved safety concerns, caution is warranted in the widespread use of favipiravir against pandemic COVID-19.
? 2020 The Authors. Journal of Virus Eradication published by Mediscript.
PMID:32405421