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Favipiravir is a pyrazine carboxamide derivative with a broad-spectrum antiviral action, mainly developed for influenza many years ago.
Favipiravir is a pyrazine carboxamide derivative with a broad-spectrum
antiviral action, mainly developed for influenza many years ago.1
The established in vitro activity of favipiravir against
SARS-CoV-2 and early clinical
experience has been found to be promising for the treatment of COVID-19.2
Pharmacological Class:
Antiviral agent
COVID-19: Favipiravir
has shown clinical improvements of up to 88% in COVID-19, with rapid reduction
in viral load by 4 days and therefore holds a considerable potential for treating
mild to moderate COVID-19 patients.3
It offers a unique mechanism of action unlike other
antiviral agents; it gets converted into an active phosphoribosylated form
(favipiravir-RTP) in cells and identified as a substrate by viral RNA
polymerase, thereby inhibiting RNA polymerase activity and preventing the
replication of viral genome.3, 4
Dosage as per
clinical study on COVID-19 patients: 1600 mg orally twice on Day 1 followed
by 600 mg orally twice daily for Day 2-14.5
The bioavailability of favipiravir is almost complete at
97.6%. The mean Cmax for the recommended dosing schedule of favipiravir is 51.5
ug/mL. Favipiravir's metabolites are predominantly renally cleared. The
apparent volume of distribution of favipiravir is 15 - 20 L. The elimination
half-life of favipiravir is estimated to range from 2 to 5.5 hours.4
Contraindicated in
Common
Uncommon and rare:
Favipiravir (FPV)
controls the disease progression of COVID-19 by inhibiting the SARS-CoV-2: A
recent open-label, nonrandomized, before-after controlled study compared the
clinical outcomes between COVID-19 patients who were treated with FPV and those
treated with Lopinavir (LPV)/ritonavir (RTV). In the FPV arm, COVID-19 patients
who received oral FPV (1600 mg twice on Day 1 followed by 600 mg twice daily
for Day 2-14) plus 5 million U interferon (IFN)-α twice daily by aerosol
inhalation were included whereas the control arm included patients who were
treated with LPV/RTV (400 mg/100 mg twice daily for Day 1-14) plus 5 million U
interferon (IFN)-α twice daily by aerosol inhalation. The primary outcomes of
the study were the changes in chest computed tomography (CT), viral clearance,
and drug safety. As compared to the control arm, the FPV arm demonstrated
shorter time for viral clearance (11 days vs. 4 days). In the FPV arm, the
improvement in chest imaging was found to be significantly better than the
control arm (91.43% vs. 62.22%). Also, the patients in the FPV arm experienced
fewer adverse events compared to the patients in the control arm. Overall
results showed promising outcomes of
favipiravir in terms of disease progression and viral clearance in COVID-19
patients. 5
Important CT summaries
from studies on Favipiravir
No. of patients: 390 (Part 1- 60 and Final part 360)
It was observed that the median elimination time for the
SARS CoV-2 was 4 days with Favipiravir compared to 9 days with standard
therapy. With Favipiravir, Day 4 of treatment 65% of patients turned RT-PCR
negative for SARS CoV-2, Day 10 of treatment, 90% of patients turned RT-PCR
negative for SARS CoV-2 Favipiravir gr. 68% reached Fever resolution on day 3
vs Std. therapy on day 6 Overall reported efficacy of favipiravir is >80%.9
This study included 2141 In Mild to Moderate COVID-19
patients. The Favipiravir treatment was associated with a clinical improvement
upto 74% by Day 7 and upto 88% by Day 14.10
In a study conducted by Cai et al. 80 patients were enrolled
and it was found that Favipiravir is associated with a significantly shorter
viral (4 days) as compared to 11 days for LPV/RTV (Lopinavir/Ritonavir). It
also showed significantly higher improvement in chest CT changes with
Favipiravir (91.4%) compared to LPV/RTV (62.2 %). Favipiravir has better Safety
profile than LPV/RTV stated the study results.11
Chang Chen et al. conducted a study in which 236 moderate
COVID-19 patients were enrolled and a superior clinical recovery rate (71.4%)
at day 7 was observed with favipiravir than that of umifenovir (55.8%).
Favipiravir had significantly shorter time to offer relief from fever and cough
than umifenovir.12
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