Elevated INR in a COVID‐19 patient after concomitant administration of favipiravir and warfarin: A case report. (2nd August 2021)

• Record Type: Journal Article
• Authors: Sekimoto, Masao; Imai, Toru; Hidaka, Shinji; Chiba, Nobutaka; Sakurai, Atsushi; Hata, Mitsumasa; Kikuchi, Norikazu
• Is Part Of: Journal of clinical pharmacy and therapeutics. Volume 47:Number 3(2022)
• Page Start: 407
• Page End: 410
• Publication Date: 2021-08-02
• Subjects: coronavirus disease of 2019 (COVID‐19) -- cytochrome P‐450 (CYP) -- drug‐drug interactions (DDIs) -- favipiravir -- international normalized ratio (INR) -- warfarin; Clinical pharmacology -- Periodicals; Chemotherapy -- Periodicals; 615
• DOI: 10.1111/jcpt.13499
• Languages: English
• ISSNs: 0269-4727

Abstract

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. Abstract : It is important to evaluate the drug–drug interactions between the limited antiviral drugs used in COVID‐19 and the drugs used to manage common comorbidities. We report a case of elevated anticoagulant action i.e., international normalized ratio (INR), when favipiravir and warfarin were used concomitantly in a patient with COVID‐19.