Favipiravir use for SARS CoV-2 infection

Bioluminescence imaging reveals enhanced SARS-CoV-2 clearance in mice with combinatorial regimens

Direct acting antivirals (DAAs) represent critical tools for combating severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants of concern (VOCs) that have escaped vaccine-elicited spike-based immunity and future coronaviruses with pandemic potential. Here, we used bioluminescence imaging to evaluate therapeutic efficacy of DAAs that target SARS-CoV-2 RNA-dependent RNA polymerase (favipiravir, molnupiravir) or main protease (nirmatrelvir) against Delta or Omicron VOCs in K18-hACE2 mice. Nirmatrelvir displayed the best efficacy followed by molnupiravir and favipiravir in suppressing viral loads in the lung. Unlike neutralizing antibody treatment, DAA monotherapy regimens did not eradicate SARS-CoV-2 in mice, but combining molnupiravir with nirmatrelvir exhibited superior additive efficacy and led to virus clearance. Furthermore, combining molnupiravir with caspase-1/4 inhibitor mitigated inflammation and lung pathology whereas combining molnupiravir with COVID-19 convalescent plasma demonstrated synergy, rapid virus clearance, and 100% survival. Thus, our study provides insights into in vivo treatment efficacies of DAAs and other effective combinations to bolster COVID-19 therapeutic arsenal.

Luminescence of favipiravir in skin appendages and sclera. A controlled study and literature review

BACKGROUND/OBJECTIVES

Favipiravir is an antiviral agent, recently used for COVID-19 infections. Several reports associate favipiravir intake with Wood's lamp fluorescence of hair, nails, and sclera. The present study was designed to elucidate the positivity rates, and sites of favipiravir-related fluorescence and to unravel the site-specific changes in fluorescence positivity rates by a function of time past exposure.

METHODS

The study population comprised 50 patients and 50 control individuals. All patients in the patient group had received a full dose of favipiravir for COVID-19 infection. Fifty volunteers served as the control group. Wood's lamp examination was performed in a completely darkened room, and the positivity rate, extent, pattern, and distribution of fluorescence were recorded.

RESULTS

Wood's light revealed fluorescence of the fingernails, toenails, sclera, and hair in 35 (70%), 35 (70%), 22 (44%), and 8 (16%) patients, respectively. No control individual tested positive by Wood's lamp. Statistical analysis revealed significant differences between patient and control groups in terms of Wood's light luminescence in the fingernails (p = .000), toenails (p = .000), sclera (p = .000) and hair (p = .003). Although fingernail, toenail, and hair fluorescence positivity rates declined or ceased at or after 91 days of favipiravir exposure, ocular fluorescence positivity rates were prolonged up to 188 days.

CONCLUSIONS

These findings confirm that favipiravir may produce fluorescence of nails, sclera, and hair, detectable by Wood's light starting from the initial month and peaking at second- and third months following exposure to the medication. Although nail and hair fluorescence tend to abate after 3 months, ocular fluorescence may persist even longer than 6 months after cessation of the medication.

Electrochemical sensor for simultaneous determination of antiviral favipiravir drug, paracetamol and vitamin C based on host-guest inclusion complex of β-CD/CNTs nanocomposite

Favipiravir (FVI) is extensively used as an effective medication against several diverse infectious RNA viruses. It is widely administered as an anti-influenza drug. Combination therapy formed from FVI, paracetamol (PAR) and vitamin C (VC) is needed for treating patients diseased by RNA viruses. Thus, an efficient electrochemical sensor is developed for detecting FVI in human serum samples. The sensor is fabricated by casting a thin layer of carbon nanotubes (CNTs) over a glassy carbon (GC) electrode surface followed by electrodeposition of another layer of β-cyclodextrin (β-CD). Under optimized conditions, the sensor shows excellent catalytic effect for FVI, PAR and VC oxidation in the concentration ranges (0.08 µM → 80 µM), (0.08 µM → 50 µM) and (0.8 µM → 80 µM) with low detection limits of 0.011 μM, 0.042 μM and 0.21 μM, respectively. The combined effect of host-guest interaction ability of β-CD for the drugs, and a large conductive surface area of CNTs improves the sensing performance of the electrode. The sensor exhibits stable response over 4 weeks, good reproducibility, and insignificant interference from common species present in serum samples. The reliability of using the sensor in serum samples shows good recovery of FVI, PAR and VC.

A highly sensitive and green electroanalytical method for the determination of favipiravir in pharmaceutical and biological fluids

BACKGROUND

Favipiravir is currently used for the treatment of coronavirus disease-2019 (COVID-19).

OBJECTIVE

A highly sensitive and eco-friendly electroanalytical method was developed to quantify favipiravir.

METHOD

The voltammetric method optimized a sensor composed of reduced graphene oxide / modified carbon paste electrode in the presence of an anionic surfactant, improving the favipiravir detection limit. The investigation reveals that favipiravir-oxidation is a diffusion-controlled irreversible process. The effects of various pH and scan rates on oxidation anodic peak current were investigated.

RESULTS

The developed method offers a wide linear dynamic range of 1.5-420 ng/mL alongside a higher sensitivity with a limit of detection in the nanogram range (0.44 ng/mL) and a limit of quantification in the low nanogram range (1.34 ng/mL).

CONCLUSION

The proposed method was applied for the determination of favipiravir in the dosage form, human plasma and urine samples. The developed method exhibited good selectivity in the presence of two potential electroactive biological interferants, uric acid which increases during favipiravir therapy and the recommended co-administered vitamin C. The organic solvent-free method greenness was evaluated via the Green Analytical Procedure Index, The present work offers a simple, sensitive and environment-friendly method fulfilling green chemistry concepts.

Combinatorial Regimens Augment Drug Monotherapy for SARS-CoV-2 Clearance in Mice

Direct acting antivirals (DAAs) represent critical tools for combating SARS-CoV-2 variants of concern (VOCs) that evolve to escape spike-based immunity and future coronaviruses with pandemic potential. Here, we used bioluminescence imaging to evaluate therapeutic efficacy of DAAs that target SARS-CoV-2 RNA-dependent RNA polymerase (favipiravir, molnupiravir) or Main protease (nirmatrelvir) against Delta or Omicron VOCs in K18-hACE2 mice. Nirmatrelvir displayed the best efficacy followed by molnupiravir and favipiravir in suppressing viral loads in the lung. Unlike neutralizing antibody treatment, DAA monotherapy did not eliminate SARS-CoV-2 in mice. However, targeting two viral enzymes by combining molnupiravir with nirmatrelvir resulted in superior efficacy and virus clearance. Furthermore, combining molnupiravir with Caspase-1/4 inhibitor mitigated inflammation and lung pathology whereas combining molnupiravir with COVID-19 convalescent plasma yielded rapid virus clearance and 100% survival. Thus, our study provides insights into treatment efficacies of DAAs and other effective combinations to bolster COVID-19 therapeutic arsenal.

Favipiravir in SARS-CoV-2 Infection: Is it Worth it?

Favipiravir is a potential antiviral drug undergoing clinical trials to manage various viral infections, including severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Favipiravir possesses antiviral properties against RNA viruses, including SARS-CoV-2. Unfortunately, these viruses do not have authorized antiviral drugs for the management of diseases resulting from their infection, hence the dire need to accentuate the discovery of antiviral drugs that are efficacious and have a broad spectrum. Favipiravir acts primarily by blocking inward and outward movements of the virus from cells. Favipiravir is a prodrug undergoing intracellular phosphorylation and ribosylation to form an active form, favipiravir-RTP, which binds viral RNA-dependent RNA polymerase (RdRp). Considering the novel mechanism of favipiravir action, especially in managing viral infections, it is vital to pay more attention to the promised favipiravir hold in the management of SARS-CoV-2, its efficacy, and dosage regimen, and interactions with other drugs. In conclusion, favipiravir possesses antiviral properties against RNA viruses, including COVID- 19. Favipiravir is effective against SARS-CoV-2 infection through inhibition of RdRp. Pre-clinical and large-scalp prospective studies are recommended for efficacy and long-term safety of favipiravir in COVID-19.

Fluorescence in the Sclera, Nails, and Teeth Secondary to Favipiravir Use for COVID-19 Infections

Favipiravir, an antiviral agent originally used for influenza infections, has become popular due to its beneficial signals in coronavirus disease. It is currently used in some countries within COVID-19 treatment protocols. This is an initial report of favipiravir-related fluorescence observed in three healthcare providers working in the same ward in our hospital. All three individuals had been diagnosed with COVID-19 two months earlier and were treated with favipiravir. None of the three individuals received hydroxychloroquine or tetracyclines. Wood's light examination led to an incidental discovery of favipiravir-induced fluorescence involving the sclera, nails, and teeth. In all patients, white linear, square, and band-like specks of fluorescence were noticed on the sclera of both eyes, some teeth, and the proximal part of all fingernails and toenails. Exposure of the eyes to the Wood's light was for a brief duration of 3 to 5 seconds during examination and photodocumentation. Favipiravir might cause bright white fluorescence of nails, sclera, and teeth, detectable by Wood's light even two months after its cessation.

Immune response and potential therapeutic strategies for the SARS-CoV-2 associated with the COVID-19 pandemic

Following onset of the first recorded case of Coronavirus disease 2019 (COVID-19) in December 2019, more than 269 million cases and over 5.3 million deaths have been confirmed worldwide. COVID-19 is a highly infectious pneumonia, caused by a novel virus called severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Currently, it poses a severe threat to human health across the globe, a trend that is likely to persist in the foreseeable future. This paper reviews SARS-CoV-2 immunity, the latest development of anti-SARS-CoV-2 drugs as well as exploring in detail, immune escape induced by SARS-CoV-2. We expect that the findings will provide a basis for COVID-19 prevention and treatment.

Favipiravir Use in Kidney Transplant Recipients with COVID-19: A Single-Center Experience

OBJECTIVES

Kidney transplant recipients are among the high-risk groups for severe COVID-19. To date, no specific antiviral agent has proved uniformly effective against SARS-CoV-2. Favipiravir, the recommended drug by the Turkish Ministry of Health, was uniformly supplied to all patients diagnosed with COVID-19 by a positive nasopharyngeal swab polymerase chain reaction test. The aim of our study was to retrospectively compare our kidney transplant recipients treated with favipiravir who developed COVID-19 infection versus those not treated with favipiravir during the clinical course of the disease, with a special emphasis on the occurrence of side effects and adverse events.

MATERIALS AND METHODS

We included 37 consecutive kidney transplant recipients with a median age of 46 years (62.2% women). Recipients included 8 with deceased donors and 29 with living related donors; median posttransplant survival was 8.0 years (IQR, 5.5-12.5 years).

RESULTS

Twenty-six patients (70.3%) received favipiravir, and 11 (29.7%) did not. There were no statistically significant differences between the groups for baseline demographic characteristics and clinical and laboratory data, except that the favipiravir-treated patients were older and had a higher requirement of oxygen treatment. There were no statistically significant differences between the 2 groups for the course and outcome of COVID-19 infection with regard to adverse side effects/events associated with favipiravir. Laboratory data at baseline, day 7, and day 30 were also comparable between the groups.

CONCLUSIONS

Although the efficacy of favipiravir for treatment of COVID-19 infection remains controversial, favipiravir is safe for kidney transplant recipients.

Voltammetric sensor based on bimetallic nanocomposite for determination of favipiravir as an antiviral drug

A novel and sensitive voltammetric nanosensor was developed for the first time for trace level monitoring of favipiravir based on gold/silver core–shell nanoparticles (Au@Ag CSNPs) with conductive polymer poly (3,4-ethylene dioxythiophene) polystyrene sulfonate (PEDOT:PSS) and functionalized multi carbon nanotubes (F-MWCNTs) on a glassy carbon electrode (GCE). The formation of Au@Ag CSNPs/PEDOT:PSS/F-MWCNT composite was confirmed by various analytical techniques, including X-ray diffraction (XRD), ultraviolet–visible spectroscopy (UV–Vis), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), and field-emission scanning electron microscopy (SEM). Under the optimized conditions and at a typical working potential of + 1.23 V (vs. Ag/AgCl), the Au@Ag CSNPs/PEDOT:PSS/F-MWCNT/GCE revealed linear quantitative ranges from 0.005 to 0.009 and 0.009 to 1.95 µM with a limit of detection 0.46 nM (S/N = 3) with acceptable relative standard deviations (1.1-4.9 %) for pharmaceutical formulations, urine, and human plasma samples without applying any sample pretreatment (1.12–4.93%). The interference effect of antiviral drugs, biological compounds, and amino acids was negligible, and the sensing system demonstrated outstanding reproducibility, repeatability, stability, and reusability. The findings revealed that this assay strategy has promising applications in diagnosing FAV in clinical samples, which could be attributed to the large surface area on active sites and high conductivity of bimetallic nanocomposite.

In silico identification of SARS-CoV-2 cell entry inhibitors from selected natural antivirals

The aim of this study is to identify potential drug-like molecules against SARS-CoV-2 virus among the natural antiviral compounds published in the Encyclopedia of Traditional Chinese Medicine. To test inhibition capability of these compounds first, we docked them with Spike protein, angiotensin-converting enzyme 2 (ACE2) (PDB ID: 6M0J) and neuropilin 1 (NRP1) (PDB ID: 7JJC) receptors, and found significant docking scores with extra precision up to -11 kcal/mol. Then, their stability in the binding pockets were further evaluated with molecular dynamics simulation. Eight natural antiviral compounds were identified as potential inhibitors against SARS-CoV-2 cell entry after 200 ns molecular dynamics simulations. We found CMP-3, CMP-4, CMP-5, CMP-6 and CMP-8 are strong binders for the spike protein, CMP-1, CMP-2, CMP-4, CMP-5 and CMP-7 are strong binders for the neuropilin receptor, and CMP-5 is a strong binder for the ACE2. Quercetin derivatives (CMP-4, CMP-5, CMP-6 and CMP-7) were found highly stable in the active domain of NRP1, ACE2 and Spike protein. Especially, CMP-5 showed an inhibitory activity for all targets. These natural antivirals may be potential drug candidates for the prevention of SARS-CoV-2 infection.

Do SARS-CoV-2 Infection (COVID-19) and the Medications Administered for Its Treatment Impair Testicular Functions?

PURPOSE

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is transmitted primarily via respiratory droplets and enters host cells through angiotensin-converting enzyme 2 (ACE-2) receptors. ACE-2 receptors have been identified in many tissues including testes. The aim of the study has been to investigate the long-term effects of SARS-CoV-2 infection (COVID-19) and its relative treatment on male reproductive health.

METHODS

Cross-sectional analysis has been performed on 49 recovered COVID-19 patients who had semen analysis prior to the COVID-19 pandemic. Those who had a recovery time lag of at least 3 months have been re-examined, and 29 eligible patients with no andrological problems have been enrolled in the study. Following a detailed physical examination and retrieval of medical history, the values of semen analysis and serum sex hormone parameters have been collected and compared before and after COVID-19 infection. The p value of <0.05 has been considered significant.

RESULTS

The average age of the 29 patients has been 31.21 ± 5.48 (range: 18-41) years. Favipiravir has been co-administered with hydroxychloroquine in 17 patients, while the remaining 12 received favipiravir treatment without hydroxychloroquine. The average time between clinical recovery from COVID-19 and collection of semen has been 4.52 ± 1.36 (range: 3-8) months. Before and after COVID-19, serum follicle-stimulating hormone, luteinizing hormone, total testosterone, and prolactin levels, as well as all semen parameters, have been comparable.

CONCLUSION

Our study demonstrated that COVID-19 and its treatment with favipiravir and hydroxychloroquine did not affect spermatogenesis and serum androgen levels in the long-term period. Further clinical studies with larger sample size are needed to confirm and support our findings.

Is SARS-CoV-2 Neutralized More Effectively by IgM and IgA than IgG Having the Same Fab Region?

Recently, recombinant monoclonal antibodies (mAbs) of three Ig isotypes (IgG, IgA, and IgM) sharing the same anti-spike protein Fab region were developed; we evaluated their neutralizing abilities using a pseudo-typed lentivirus coated with the SARS-CoV-2 spike protein and ACE2-transfected Crandell–Rees feline kidney cells as the host cell line. Although each of the anti-SARS-CoV-2 mAbs was able to neutralize the spike-coated lentiviruses, IgM and IgA neutralized the viral particles at 225-fold and 125-fold lower concentrations, respectively, than that of IgG. Our finding that the neutralization ability of Igs with the same Fab domain was dramatically higher for IgM and IgA than IgG mAbs suggests a strategy for developing effective and affordable antibody therapies for COVID-19. The efficient neutralization conferred by IgM and IgA mAbs can be explained by their capacity to bind multiple virions. While several IgG mAbs have been approved as therapeutics by the FDA, there are currently no IgM or IgA mAbs available. We suggest that mAbs with multiple antigen-binding sites such as IgM and IgA could be developed as the new generation of therapy.

First electrochemical evaluation of favipiravir used as an antiviral option in the treatment of COVID-19: A study of its enhanced voltammetric determination in cationic surfactant media using a boron-doped diamond electrode

Favipiravir, a promising antiviral agent, is undergoing clinical trials for the potential treatment of the novel coronavirus disease 2019 (COVID-19). This is the first report for the electrochemical activity of favipiravir and its electroanalytical sensing. For this purpose, the effect of cationic surfactant, CTAB was demonstrated on the enhanced accumulation of favipiravir at the surface of cathodically pretreated boron-doped diamond (CPT-BDD) electrode. At first, the electrochemical properties of favipiravir were investigated in the surfactant-free solutions by the means of cyclic voltammetry. The compound presented a single oxidation step which is irreversible and adsorption controlled. A systematic study of various operational conditions, such as electrode pretreatment, pH of the supporting electrolyte, concentration of CTAB, accumulation variables, and instrumental parameters on the adsorptive stripping response, was examined using square-wave voltammetry. An oxidation signal at around +1.21 V in Britton-Robinson buffer at pH 8.0 containing 6 × 10^-4 M CTAB allowed to the adsorptive stripping voltammetric determination of favipiravir (after 60 s accumulation step at open-circuit condition). The process could be used in the concentration range with two linear segments of 0.01-0.1 μg mL^-1 (6.4 × 10^-8-6.4 × 10^-7 M) and 0.1-20.0 μg mL^-1 (6.4 × 10^-7-1.3 × 10^-4 M). The limit of detection values were found to be 0.0028 μg mL^-1 (1.8 × 10^-8 M), and 0.023 μg mL^-1 (1.5 × 10^-7 M) for the first and second segments of calibration graph, respectively. The feasibility of developed methodology was tested to the analysis of the commercial tablet formulations and model human urine samples.

Nucleoside Analogs and Nucleoside Precursors as Drugs in the Fight against SARS-CoV-2 and Other Coronaviruses

Coronaviruses (CoVs) are positive-sense RNA enveloped viruses, members of the family Coronaviridae, that cause infections in a broad range of mammals including humans. Several CoV species lead to mild upper respiratory infections typically associated with common colds. However, three human CoV (HCoV) species: Severe Acute Respiratory Syndrome (SARS)-CoV-1, Middle East Respiratory Syndrome (MERS)-CoV, and SARS-CoV-2, are responsible for severe respiratory diseases at the origin of two recent epidemics (SARS and MERS), and of the current COronaVIrus Disease 19 (COVID-19), respectively. The easily transmissible SARS-CoV-2, emerging at the end of 2019 in China, spread rapidly worldwide, leading the World Health Organization (WHO) to declare COVID-19 a pandemic. While the world waits for mass vaccination, there is an urgent need for effective drugs as short-term weapons to combat the SARS-CoV-2 infection. In this context, the drug repurposing approach is a strategy able to guarantee positive results rapidly. In this regard, it is well known that several nucleoside-mimicking analogs and nucleoside precursors may inhibit the growth of viruses providing effective therapies for several viral diseases, including HCoV infections. Therefore, this review will focus on synthetic nucleosides and nucleoside precursors active against different HCoV species, paying great attention to SARS-CoV-2. This work covers progress made in anti-CoV therapy with nucleoside derivatives and provides insight into their main mechanisms of action.

Favipiravir Effects on the Control of Clinical Symptoms of Hospitalized COVID-19 Cases: An Experience with Iranian Formulated Dosage Form

Coronavirus disease -19 (COVID-19) pandemic, caused by SARS-CoV-2, has gradually spread worldwide, becoming a major public health event. This situation requires designing a novel antiviral agent against the SARS-CoV-2; however, this is time-consuming and the use of repurposed medicines may be promising. One such medicine is favipiravir, primarily introduced as an anti-influenza agent in east world. The aim of this study was to evaluate the efficacy and safety of favipiravir in comparison with lopinavir-ritonavir in SARS-CoV-2 infection. In this randomized clinical trial, 62 patients were recruited. These patients had bilateral pulmonary infiltration with peripheral oxygen saturation lower than 93%. The median time from symptoms onset to intervention initiation was seven days. Favipiravir was not available in the Iranian pharmaceutical market, and it was decided to formulate it at the research laboratory of School of Pharmacy, Shahid Beheshti University of Medical Sciences, Tehran, Iran. The patients received favipiravir tablet at a dose of 1600 mg orally twice a day for day one and then 600 mg orally twice a day for days 2 to 6. In the second group, the patients received lopinavir-ritonavir combination tablet at a dose of 200/50 mg twice a day for seven days. Fever, cough, and dyspnea were improved significantly in favipiravir group in comparison with lopinavir-ritonavir group on days four and five. Mortality rate and ICU stay in both groups were similar, and there was no significant difference in this regard (P = 0.463 and P = 0.286, respectively). Chest X-ray improvement also was not significantly different between the two groups. Adverse drug reactions occurred in both groups, and impaired liver enzymes were the most frequent adverse effect. In conclusion, early administration of oral favipiravir may reduce the duration of clinical signs and symptoms in patients with COVID-19 and hospitalization period. The mortality rate also should be investigated in future clinical trials.