Dermatologic Therapy | 2021
A finding associated with favipiravir‐associated photosensitivity: Yellow‐green fluorescence in the lunulae, scalp, and face
Abstract
Dear Editor, Coronavirus Disease-2019 (COVID-19) has caused the pandemic since 11 March 2020. It is the top priority problem that all humanity has been seeking a solution for about a year. More than 1.5 million people have died of COVID-19 by 5 December 2020. There is no specific FDA-approved treatment for COVID-19 so far. Several therapeutic agents are recommended in guidelines: Favipiravir, remdesivir, lopinavir/ritonavir, chloroquine/hydroxychloroquine, various antibiotics, anticoagulant agents, corticosteroids, intravenous immunoglobulin, interferon, and tocilizumab. Türsen et al comprehensively highlighted the possible cutaneous adverse reactions associated with these drugs, and they drew attention to the photosensitivity reaction of lopinavir/ritonavir and checkpoints inhibitors (CD200-CD200R1 inhibitors and anti-PD agents). In the report on the deliberation results published by the Japanese Pharmaceuticals and Medical Devices Agency for favipiravir in 2014, it is highlighted that the drug was found to be phototoxic in studies conducted on mice and guinea pigs. Besides, in the comparative studies with quinolones made with 100 mg/kg intravenous favipiravir in guinea pigs, it was pronounced that the severity of phototoxicity was less than ciprofloxacin but comparable to levofloxacin at the same dose. Therefore, the necessity of measures for the clinical use of favipiravir has been emphasized. We would like to share our incidental observations of yellow-green fluorescence in the lunulae of fingernails and other localizations under Wood s light. An otherwise healthy, 31-year-old male patient (corresponding author) with complaints of fever, headache, myalgia, and cough was diagnosed with confirmed COVID-19. Therefore, the patient used only favipiravir (2 × 1600 mg [1st day] loading dose followed by 2 × 600 mg/day [4 days]). He had mild disease, and his quarantine ended after the 10th day. On the 17th day after the diagnosis, yellow-green fluorescence was noticed in the lunulae of fingernails while using Wood s light (Figure 1A). Thus, we started performing Wood s light examination for many patients examined in the COVID-19 outpatient clinics. With our experience, we made the following preliminary conclusions: