Introduction
Favipiravir was approved in Japan for use in the event of an outbreak of
novel or re-emerging influenza viral infections, where other influenza
antiviral drugs are either not or insufficiently effective [1].
Favipiravir is a new antiviral drug against influenza. Favipravir is
metabolized into favipiravir ribosyl triphosphate (favipiravir RTP) by
an intracellular enzyme, and favipiravir RTP selectively inhibits RNA
polymerase (RNA-dependent RNA polymerase) of the influenza virus,
preventing replication of the influenza virus. The mechanism of action
of favipiravir is the selective inhibition of RNA polymerase by
favipiravir ribosyl triphosphate formed by cellular enzymes in the
influenza virus leading to antiviral activity [2]. In an open-label
comparative controlled study of patients with Covid-19, those treated
with favipiravir apeared to have faster viral clearance and higher rates
of improvement in chest imaging, and in another prospective, randomized,
controlled, open-label multicenter trial favipiravir significantly
improved the latency to relief for pyrexia and cough [3,4].
The bioequivalence study is required for generic orally administered
Favipiravir products by certain regulatory authorities [5, 6].
Therefore, this study aims to compare the pharmacokinetic properties of
a generic formulation to the reference product and to demonstrate the
bioequivalence of the products with respect to the rate and extent of
absorption of Favipiravir in healthy male subjects under fasting
conditions.