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Case Reports
. 2022 Mar;47(3):407-410.
doi: 10.1111/jcpt.13499. Epub 2021 Aug 2.

Elevated INR in a COVID-19 patient after concomitant administration of favipiravir and warfarin: A case report

Masao Sekimoto  1 , Toru Imai  2 , Shinji Hidaka  3 , Nobutaka Chiba  4 , Atsushi Sakurai  4 , Mitsumasa Hata  5 , Norikazu Kikuchi  1
Affiliations
Case Reports

Elevated INR in a COVID-19 patient after concomitant administration of favipiravir and warfarin: A case report

Masao Sekimoto et al. J Clin Pharm Ther. 2022 Mar.

Abstract

What is known and objective: Favipiravir is a promising treatment candidate for managing coronavirus disease 2019 (COVID-19). Warfarin has many drug interactions, but no interactions with favipiravir have been reported.

Case summary: Our patient was taking warfarin for deep vein thrombosis. The international normalized ratio (INR) was stable (1.65 to 2.0); however, it increased to 4.63 after administering favipiravir. The patient had no other factors justifying this change.

What is new and conclusion: Favipiravir and warfarin might have previously unidentified drug interactions that elevated the INR. Therefore, INR must be closely monitored when they are concomitantly administered in COVID-19 patients.

Keywords: coronavirus disease of 2019 (COVID-19); cytochrome P-450 (CYP); drug-drug interactions (DDIs); favipiravir; international normalized ratio (INR); warfarin.

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Conflict of interest statement

No conflicts of interest have been declared.

Figures

FIGURE 1
FIGURE 1
Time course of administration of warfarin and favipiravir and changes in INR and AST/ALT [Colour figure can be viewed at wileyonlinelibrary.com]
See this image and copyright information in PMC

References

    1. Agrawal U, Raju R, Udwadia ZF. Favipiravir: A new and emerging antiviral option in COVID‐19. Med J Armed Forces India. 2020;76(4):370‐376. - PMC - PubMed
    1. Dabbous HM, Abd‐Elsalam S, El‐Sayed MH, et al. Efficacy of favipiravir in COVID‐19 treatment: a multi‐center randomized study. Arch Virol. 2021;166(3):949‐954. - PMC - PubMed
    1. Udwadia ZF, Singh P, Barkate H, et al. Efficacy and safety of favipiravir, an oral RNA‐dependent RNA polymerase inhibitor, in mild‐to‐moderate COVID‐19: A randomized, comparative, open‐label, multicenter, phase 3 clinical trial. Int J Infect Dis. 2021;103:62‐71. - PMC - PubMed
    1. Du YX, Chen XP. Favipiravir: pharmacokinetics and concerns about clinical trials for 2019‐nCoV infection. Clin Pharmacol Ther. 2020;108(2):242‐247. - PubMed
    1. Fujifilm (Corporation) . Toyama Chemical Co., Ltd. (Fujifilm). The Drug Interview Form of Favipiravir (Avigan®). http://fftc.fujifilm.co.jp/med/abigan/pack/pdf/abigan_if_01.pdf. Accessed March 27, 2021 (in Japanese); 2019 (April. 2019 version).

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