Favipiravir (FPV), a pyrazine carboxamide derivative (6-fluoro-3-hydroxy-2-pyrazinecarboxamide) is a broad-spectrum anti-viral drug which acts against many species of Arenaviridae, Bunyaviridae, Caliciviridae, Filoviridae, Flaviviridae, Orthomyxoviridae, Paramyxoviridae, Picornaviridae, Rhabdoviridae, Togaviridae groups. According to the WHO, FPV may be a new hope for the treatment severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections and for this it has undergone for a number of clinical trials. However, human hypoxanthine guanine phosphoribosyltransferase (HPRT) is believed to play a key role in its physiological activation process, therefore, the patients having Kelley-Seegmiller syndrome, Lesch–Nyhan syndrome, myocardial ischemia, hyperuricemia, anemia, and phosphoribosyl diphosphate (PRPP) synthetase superactivity due to deficiency to this enzyme might be a limiting factor for the effectiveness of this drug in these types of patients.