Uric Acid Elevation by Favipiravir, an Antiviral Drug

Tohoku J Exp Med. 2020 Jun;251(2):87-90. doi: 10.1620/tjem.251.87.


In light of the recent pandemic, favipiravir (Avigan®), a purine nucleic acid analog and antiviral agent approved for use in influenza in Japan, is being studied for the treatment of coronavirus disease 2019 (COVID-19). Increase in blood uric acid level is a frequent side effect of favipiravir. Here, we discussed the mechanism of blood uric acid elevation during favipiravir treatment. Favipiravir is metabolized to an inactive metabolite M1 by aldehyde oxidase and xanthine oxidase, and excreted into urine. In the kidney, uric acid handling is regulated by the balance of reabsorption and tubular secretion in the proximal tubules. Favipiravir and M1 act as moderate inhibitors of organic anion transporter 1 and 3 (OAT1 and OAT3), which are involved in uric acid excretion in the kidney. In addition, M1 enhances uric acid reuptake via urate transporter 1 (URAT1) in the renal proximal tubules. Thus, favipiravir is thought to decrease uric acid excretion into urine, resulting in elevation of uric acid levels in blood. Elevated uric acid levels were returned to normal after discontinuation of favipiravir, and favipiravir is not used for long periods of time for the treatment of viral infection. Thus, the effect on blood uric acid levels was subclinical in most studies. Nevertheless, the adverse effect of favipiravir might be clinically important in patients with a history of gout, hyperuricemia, kidney function impairment (in which blood concentration of M1 increases), and where there is concomitant use of other drugs affecting blood uric acid elevation.

Keywords: COVID-19; SARS-CoV-2; favipiravir; hyperuricemia; influenza.

Publication types

  • Review

MeSH terms

  • Aldehyde Oxidase / metabolism
  • Amides / adverse effects*
  • Amides / pharmacokinetics
  • Amides / urine
  • Antiviral Agents / adverse effects*
  • Antiviral Agents / pharmacokinetics
  • Biotransformation
  • COVID-19
  • Coronavirus Infections / drug therapy*
  • Drug Interactions
  • Humans
  • Hyperuricemia / chemically induced*
  • Hyperuricemia / physiopathology
  • Kidney / metabolism
  • Kidney Diseases / metabolism
  • Molecular Structure
  • Organic Anion Transport Protein 1 / antagonists & inhibitors
  • Organic Anion Transporters / metabolism
  • Organic Anion Transporters, Sodium-Independent / antagonists & inhibitors
  • Organic Cation Transport Proteins / metabolism
  • Pandemics
  • Pneumonia, Viral / drug therapy*
  • Pyrazines / adverse effects*
  • Pyrazines / pharmacokinetics
  • Pyrazines / urine
  • Uric Acid / blood*
  • Xanthine Oxidase / metabolism


  • Amides
  • Antiviral Agents
  • Organic Anion Transport Protein 1
  • Organic Anion Transporters
  • Organic Anion Transporters, Sodium-Independent
  • Organic Cation Transport Proteins
  • Pyrazines
  • SLC22A12 protein, human
  • organic anion transport protein 3
  • Uric Acid
  • Xanthine Oxidase
  • Aldehyde Oxidase
  • favipiravir