Efficacy and safety of favipiravir, an oral RNA-dependent RNA polymerase inhibitor, in mild-to-moderate COVID-19: A randomized, comparative, open-label, multicenter, phase 3 clinical trial

A deep drug prediction framework for viral infectious diseases using an optimizer-based ensemble of convolutional neural network: COVID-19 as a case study

The SARS-CoV-2 outbreak highlights the persistent vulnerability of humanity to epidemics and emerging microbial threats, emphasizing the lack of time to develop disease-specific treatments. Therefore, it appears beneficial to utilize existing resources and therapies. Computational drug repositioning is an effective strategy that redirects authorized drugs to new therapeutic purposes. This strategy holds significant promise for newly emerging diseases, as drug discovery is a lengthy and expensive process. Through this study, we present an ensemble method based on the convolutional neural network integrated with genetic algorithm and deep forest classifier for virus-drug association prediction (CGDVDA). We generated feature vectors by combining drug chemical structure and virus genomic sequence-based similarities, and extracted prominent deep features by applying the convolutional neural network. The convoluted features are optimized using the genetic algorithm and classified using the ensemble deep forest classifier to predict novel virus-drug associations. The proposed method predicts drugs for COVID-19 and other viral diseases in the dataset. The model could achieve ROC-AUC scores of 0.9159 on fivefold cross-validation. We compared the performance of the model with state-of-the-art approaches and classifiers. The experimental results and case studies illustrate the efficacy of CGDVDA in predicting drugs against viral infectious diseases.

Computational predictions of artificial nucleoside triphosphates as potent inhibitors of RNA-dependent RNA polymerase of the ZIKA virus

As the RNA-dependent RNA polymerase (RdRp) of the Zika virus (ZIKV) is responsible for replicating the viral RNA genome inside host cells, its inhibition is necessary to control the Zika viral disease. Here, the interactions of 16 artificial RNA and DNA nucleoside triphosphates with the substrate active site of RdRp are studied in detail by using the molecular docking technique. The top 8 hits containing ligands such as ZTP, BTP, STP, XTP, dZTP, dBTP, dSTP, and dXTP were further studied by using molecular dynamics, and MM/GBSA Free-energy methods. It is revealed that among various nucleoside triphosphates studied herein, the dBTP would bind to RdRP most strongly with a binding free energy (ΔGbind) of -70.40 ± 4.6 kcal/mol followed by dZTP with a ΔGbind of -67.37 ± 3.1 kcal/mol. The binding of these artificial nucleoside triphosphates to RdRp is about 22-26 kcal/mol more stable than that of the natural nucleoside triphosphate GTP. Therefore, it is expected that dBTP and dZTP would inhibit the activities of RdRp strongly. The molecular mechanisms of inhibition of RdRp activities are also discussed and compared with experimental studies.

Experimental evaluation of favipiravir (T-705)-induced liver and kidney toxicity in rats

Favipiravir is an antiviral drug that selectively and potently inhibits RNA-dependent RNA polymerase of various RNA viruses. Its empirical use has increased with the COVID-19 pandemic. This study aimed to investigate the potential toxicological effects of favipiravir administration on healthy rats' liver and kidney tissues. Four groups were established in the survey (n = 10): Control, Low-dose favipiravir (100 mg/kg/d), Medium-dose favipiravir (200 mg/kg/d), and High-dose favipiravir (300 mg/kg/d). On the first day of the study, a loading dose equivalent to twice the maintenance dose was administered. On the eleventh day, liver and kidney tissues were collected for histopathological and immunohistochemical analyses. According to our results, favipiravir caused various histopathological damages in the liver and kidneys and led to alterations in the levels of cytokines associated with inflammation (IL-6, TGF-β, TNF-α, IL-1β, IFN-γ). Co-administration of favipiravir with various protective agents may be needed to mitigate potential damage to the liver and kidneys.

Antivirals in COVID-19: A Focus on Pediatric Cardiac Patients

The COVID-19 pandemic created an unprecedented public health crisis, driven by its rapid global spread and the urgent need for worldwide collaborative interventions to contain it. This urgency spurred the search for therapeutic agents to prevent or manage the infection. Among these, various types of antivirals emerged as a prominent treatment option, supported by a wealth of observational studies and randomized controlled trials. The results from such studies conflict, with some concluding efficacy and others the lack thereof, with variability also occurring depending on the severity of COVID-19 in the studied population. In addition, many agents have been explored using randomized controlled trials-the gold standard in evaluating the efficacy of an intervention-to only a limited degree, with most of the evidence behind their use concluded using observational studies. Thus, the sheer volume of data has made it challenging to resolve inconsistencies and determine true efficacy. Furthermore, there is a paucity in the literature regarding the use of antivirals in the pediatric population infected with COVID-19, with their use being extrapolated from the results of studies done on adult patients. As such, additional trials are needed to solidify the effectiveness of antivirals in managing COVID-19, particularly in the underexplored and especially vulnerable pediatric cardiac patients. Therefore, utilizing the results from randomized controlled trials, this narrative review evaluates the rationale behind the use of antivirals, summarizes the findings from the literature, and concludes with a focused discussion on their application in pediatric cardiac patients.

The development of therapeutics and vaccines against COVID-19

Since the COVID-19 pandemic, it has caused a great threat to the global economy and public health, initiatives have been launched to control the spread of the virus. To explore the efficacy of drugs, a large number of clinical trials have been carried out, with the purpose of providing guidelines based on high-quality evidence for clinicians. We mainly discuss therapeutic agents for COVID-19 and explain the mechanism, including antiviral agents, tocilizumab, Janus kinase (JAK) inhibitors, neutralizing antibody therapies and corticosteroids. In addition, the COVID-19 vaccine has been proven to be efficacious in preventing SARS-CoV-2 infection. We systematically analyzed four mainstream vaccine platforms: messenger RNA (mRNA) vaccines, viral vector vaccines, inactivated vaccines and protein subunit vaccines. We evaluated the therapeutic effects of drugs and vaccines through enumerating the most typical clinical trials. However, the emergence of novel variants has further complicated the interpretation of the available clinical data, especially vaccines and antibody therapies. In the post-epidemic era, therapeutic agents are still the first choice for controlling the progression of disease, whereas the protective effect of vaccines against different strains should be assessed comprehensively.

SARS-CoV-2 drug resistance and therapeutic approaches

In light of the transition of COVID-19 from a pandemic to an endemic phase, there is still a dire need to address challenges associated with drug resistance, particularly among immunocompromised and high-risk populations. This review explores the current state of research on SARS-CoV-2 drug resistance and underscores the ongoing need for effective therapeutic strategies. It critically evaluates existing knowledge on resistance mechanisms and therapeutic options, aiming to consolidate information and highlight areas for future research. By examining the complex interactions between the virus and its host, the review advocates for a multifaceted approach, including combination therapies, targeted drug development, and continuous surveillance of viral mutations. It also emphasizes the impact of evolving viral variants on antiviral efficacy and suggests adaptive treatment protocols. This review aims to enhance our understanding of SARS-CoV-2 drug resistance and contribute to more effective management of COVID-19 through a discussion of promising strategies such as drug repurposing and combination therapies.

ACVPICPred: Inhibitory activity prediction of anti-coronavirus peptides based on artificial neural network

Peptides, as small molecular compounds, exhibit prominent advantages in the inhibition of coronaviruses due to their safety, efficacy, and specificity, holding great promise as drugs against coronaviruses. The rapid and efficient determination of the activity of anti-coronavirus peptides (ACovPs) can greatly accelerate the development of drugs for treating coronavirus-related diseases. Hence, we present ACVPICPred, a computational model designed to predict the inhibitory activity of ACovPs based on their sequences and structural information. By leveraging bioinformatics tools AlphaFold3 for structural predictions and several feature extraction methods, the model integrates both sequence and structural features to enhance prediction accuracy. To address the limitations of existing datasets, we employed data augmentation techniques, including the introduction of noise and the SMOGN, to improve the model robustness. The model's performance was evaluated through five-fold cross-validation, achieving a Pearson correlation coefficient of 0.7668 (p < 0.05) and an R² of 0.5880 on the training dataset. Overall, in our study, compared to models that only use sequence features, models that combine structural features have achieved more robust results in various evaluation metrics. ACVPICPred is freely accessible at the following URL: http://i.uestc.edu.cn/acvpICPred/main/Main.php.

Assessing favipiravir impact on SARS-CoV-2 transmission within households: Insights from a multi-center study (FaviPrev)

Background

While certain studies have demonstrated that antiviral treatment administered to index patients with influenza can mitigate the transmission within households, the efficacy of anti-SARS-CoV-2 agents in curtailing household transmission remains to be conclusively established.

Methods

A retrospective study conducted from April 2021 to May 2022 across multiple centers in Thailand compared 892 individuals treated with favipiravir to 84 who received standard treatment among mild to moderate COVID-19 index patients. The study focused on the impact of favipiravir treatment in reducing household SARS-CoV-2 transmission by examining the secondary attack rate.

Results

Favipiravir significantly reduced household SARS-CoV-2 transmission, comparing 1836 household contacts with favipiravir-treated index cases to 170 contacts whose index cases received standard care. Favipiravir led to a 58 % secondary attack rate, substantially lower than the 71.8 % observed with standard treatment, representing a 54 % reduction in transmission likelihood, with an odds ratio of 0.46 (95 % confidence interval [CI] [0.23-0.89]). Index cases treated with favipiravir also demonstrated a relative risk reduction of 0.19 in transmission (95 % CI [0.11-0.27]). Remarkably, favipiravir effectiveness was most notable in unvaccinated index cases, those with symptomatic infections, individuals living in shared spaces like dormitories, flats, or apartments, and those not adhering to mask-wearing within their households.

Conclusions

Favipiravir has demonstrated in this study an indirect role in reducing household SARS-CoV-2 transmission, showing notable efficacy in symptomatic and unvaccinated index cases. This breakthrough highlights its potential in broader public health strategies. Exploring the roles and challenges of other anti-SARS-CoV-2 agents remains a vital goal in ongoing research.

Assessment of Favipiravir and Remdesivir in Combination for SARS-CoV-2 Infection in Syrian Golden Hamsters

Favipiravir (FVP) and remdesivir (RDV) have demonstrable antiviral activity against SARS-CoV-2. Here, the efficacy of FVP, RDV, and FVP with RDV (FVP + RDV) in combination was assessed in Syrian golden hamsters challenged with SARS-CoV- 2 (B.1.1.7) following intraperitoneal administration. At day 4 post infection, viral RNA and viral antigen expression were significantly lower in lungs for all three treatment groups compared to the sham treatment. Similarly, viral titres in the lungs were lower in all treatment groups compared to the sham treatment. The FVP + RDV combination was the only treatment group where viral RNA in nasal turbinate and lung, virus titres in lung, and viral antigen expression (lung) were all lower than those for the sham treatment group. Moreover, lower viral titre values were observed in the FVP + RDV group compared to other treatment groups, albeit only significantly lower in comparison to those in the RDV-only-treated group. Further assessment of the potential utility of FVP in combination with RDV may be warranted. Future studies should also consider whether the combination of these two drugs may reduce the speed at which drug resistance mutations are selected.

Advancements in Antiviral Therapy: Favipiravir Sodium in Nasal Formulation

Favipiravir (FPV) is an Active Pharmaceutical Ingredient (API) known to have lower solubility in aqueous solvents. In the current study, efforts were made to generate a crystalline Favipiravir Sodium Salt (NaFPV) for enhanced solubility in aqueous media. The in-house generated NaFPV was characterized by NMR studies and its sodium content was determined by Flame Emission Spectroscopy (FES) as a confirmation of salt formation. Its solubility was determined where-in the solubility of NaFPV in water was about 100 times greater than FVP. FPV and NaFPV nasal spray formulations were prepared and its activity was determined against human coronavirus (hCoV) 229E strain. In the anti-hCoV assay as compared to FPV, NaFPV showed almost threefold higher anti-viral activity than its unmodified counterpart. Accelerated stability and spray pattern characteristics of both the formulations were studied. Interestingly, NaFPV showed higher physical stability during storage at conditions 40 ± 2 °C/ 75% ± 5% RH. The nasal spray formulations of both FPV and NaFPV showed ideal plume geometry and spray pattern of acceptable specifications. Due to its improvement in terms of solubility, NaFPV will have higher rate and extent of absorption, and faster onset of the therapeutic effect and may appear to be a feasible alternative to regular favipiravir for use in solid dosage forms.

Convenient screening of the reproductive toxicity of favipiravir and antiviral drugs in Caenorhabditis elegans

Reproductive toxicity is one of the major concerns in drug development. Thus, we have developed its screening system using Caenorhabditis elegans, which has a life cycle of three days and similar coding genes as humans. Antiviral nucleoside analogs used for acute infections are known to cause reproductive toxicity, contraindicated for pregnant women, and are used for comparing their reproductive toxicity in C. elegans and experimental animals. None of the drug treatments affected the number of offspring and the concentrations without toxicity to nematodes were consistent with no cytotoxicity or toxicity in experimental animals or humans. Favipiravir, ribavirin, molnupiravir (NHC), acyclovir, ganciclovir, zidovudine, and thalidomide significantly increased the incidence of arrested embryos but amenamevir, letermovir, and guanosine did not. RNA-dependent RNA polymerase (RdRp) inhibitors, in the order of favipiravir, ribavirin, and NHC increased the incidence of arrested embryos, possibly due to the specificity of favipiravir for RdRp and less cytotoxicity. RdRp inhibitors would impair RNA interference through RdRp expressed by telomerase reverse transcriptase during embryogenesis and cause embryo-fetal toxicity. The incidence of arrested embryos may be affected by differences in the substrate specificity of DNA polymerases and metabolism between C. elegans, animals, and humans. The concordance between the results of the screening system for reproductive toxicity of antivirals in C. elegans and those in experimental animals based on the International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use, reproductive toxicology confirms its appropriateness as a screening system for reproductive toxicity. Favipiravir and zidovudine were the least toxic to C. e legans among the antiviral drugs examined.

Challenges of consolidating evidence collected during a pandemic and lessons for the future

OBJECTIVE

To illustrate the challenges encountered when gathering rapidly synthesized evidence in response to the coronavirus disease 2019 (COVID-19) pandemic.

METHODS

In this article, we describe the challenges encountered when we performed a systematic literature review (SLR) of randomized controlled trials (RCTs) on the efficacy and safety of treatments for severe COVID-19. The methods of the SLR are described in full, to show the context of our objectives. Then we use the results of the SLR to demonstrate the problems of producing synthesized evidence in this setting.

RESULTS

Various challenges were identified during this SLR. These were primarily a result of heterogeneity in the study methodology of eligible studies. Definitions of the patient populations and outcome measurements were highly variable and the majority of studies demonstrated a high risk of bias, preventing quantitative synthesis of the collated evidence.

CONCLUSION

Consolidating evidence from RCTs evaluating COVID-19 interventions was problematic. Guidance is needed for scenarios with high rapid output in primary research.

A novel LC-MS/MS method for the determination of favipiravir ribofuranosyl-5'-triphosphate (T-705-RTP) in human peripheral mononuclear cells

Favipiravir is a broad-spectrum antiviral that is metabolised intracellularly into the active form, favipiravir ribofuranosyl-5'-triphosphate (F-RTP). Measurement of the intracellular concentration of F-RTP in mononuclear cells is a crucial step to characterising the pharmacokinetics of F-RTP and to enable more appropriate dose selection for the treatment of COVID-19 and emerging infectious diseases. The described method was validated over the range 24 - 2280 pmol/sample. Peripheral blood mononuclear cells (PBMCs) were isolated from whole blood and lysed using methanol-water (70:30, v/v) before cellular components were precipitated with acetonitrile and the supernatant further cleaned by weak anion exchange solid phase extraction. The method was found to be both precise and accurate and was successfully utilised to analyse F-RTP concentrations in patient samples collected as part of the AGILE CST-6 clinical trial.

Unveiling therapeutic dynamics: An in-depth comparative analysis of neutralizing monoclonal antibodies and favipiravir in alleviating COVID-19 outpatients impacts among middle-aged and special populations (MA-FAST)

BACKGROUND

Neutralizing monoclonal antibodies (NMabs) are recognized for their efficacy against non-severe COVID-19. However, spike protein mutations may confer resistance. This study evaluates the effectiveness of favipiravir (FPV) versus NMabs in preventing severe COVID-19 in special populations.

METHODS

A retrospective cohort was conducted on middle-aged, elderly, diabetic, or obese patients with COVID-19 treated with either FPV or NMabs. Propensity score matching (PSM) was used for analysis.

RESULTS

The study included 1410 patients, resulting in four cohorts: middle-aged (36), elderly (48), diabetic (46), and obese (28) post-PSM. No significant differences were noted in 28-day emergency department (ED) visits across all groups between NMabs and FPV treatments, despite lower immunity in the FPV group. However, the diabetic group treated with FPV had higher 28-day hospitalization and oxygen supplemental, with no differences in the other groups. Intensive care unit (ICU) admissions, invasive mechanical ventilation, and mortality rates were similar between the two treatments.

CONCLUSIONS

Early dose-adjusted FPV showed no difference from NMabs in preventing ED visits, ICU admissions, ventilator needs, or mortality among patients with major comorbidities. Diabetic patients on FPV experienced higher hospitalizations and oxygen needs, with no observed differences in other groups. FPV may be a viable alternative, especially in settings with limited resources.

Evaluation of the relationship of treatment and vaccination with prognosis in patients with a diagnosis of COVID-19

PURPOSE

Coronavirus disease 2019 (COVID-19) has affected millions of people worldwide and caused mortality. Many factors have been reported to affect the prognosis of COVID-19. In this study, we aimed to investigate the effects of drug therapy and vaccination on prognosis in patients hospitalized with a COVID-19 diagnosis.

METHODS

In this single-center, cross-sectional study, data were retrospectively collected from patients receiving inpatient treatment at a university hospital with a diagnosis of COVID-19 between January 1, 2020, and April 30, 2022. The patients' demographic and clinical characteristics were recorded. The Chi-square, Cox and logistic regression was performed, P < 0.05 was considered statistically significant.

RESULTS

Total 1723 patients (50.1% were men, mean age: 60.6 ± 16.90) who had not been vaccinated rate was 27.0% (> 3 doses: 45.7%). Mortality rate was 17.0%. Increasing age, male, a high Charlson Comorbidity Index (CCI), and no vaccination significantly increased mortality (P < 0.05). The mortality rate was significantly lower in the chloroquine treatment group than in the other treatment groups. Increasing age, male, and a high CCI were determined to be factors that significantly increased the length of hospital stay (LOHS). LOHS found to be significantly lower in the favipiravir or chloroquine groups compared to the remaining treatment groups (P < 0.001). Both mortality and the LOHS significantly differed according to AST, d-dimer, ferritin, and GFR.

CONCLUSION

This study primarily investigated the effect of treatment and vaccination on the prognosis of COVID-19. This was determined to be prepared for another potential pandemic that may arise due to COVID-19.

Hospitalization Endpoint in Clinical Trials of Outpatient Settings: using Anti-SARS-COV-2 Therapy as an Example

Purpose

In response to the COVID-19 pandemic, the World Health Organization (WHO) developed a set of outcome measures for trials primarily aimed at hospitalised patients. However, a gap exists in defining outcome standards for non-hospitalised patients. Therefore, this study aims to discuss hospitalisation as a primary outcome in outpatient trials and its potential pitfalls, specifically focusing on trials related to anti-SARS-COV-2 therapy.

Methods

In this narrative review, researchers thoroughly searched MEDLINE and ClinicalTrials.gov from January 2020 to December 2022, targeting Phase III randomized controlled trials involving outpatients with mild-to-moderate COVID-19. The trials were specifically related to anti-SARS-COV-2 monoclonal antibodies or antiviral agents. The study collected essential data, including the type of intervention, comparator, primary objective, primary endpoint, and the use of estimands in the trial.

Results

The search identified 12 trials that evaluated the efficacy of anti-SARS COV-2 therapies in a predefined population. Three studies used hospitalisation and death as primary endpoints in high-risk patients receiving monoclonal antibodies. Nine studies assessed the efficacy of several antiviral agents: four trials used hospitalisation and death as the main endpoints, while others used different measures such as virologic measures using the Reverse Transcription-Polymerase Chain Reaction test (RT-PCR), the eight-point WHO ordinal scale, symptom alleviation by Day 7 and time to clinical response.

Conclusion

Choosing hospitalization as an endpoint may provide meaningful data such as the cost-effectiveness ratio of a drug. However, different hospital utilisation patterns and investigator decisions could bias clinical outcomes if no specific criteria are considered. Therefore, investigators should have clear criteria for determining variables that influence this measure.

Favipiravir does not improve viral clearance in mild to moderate COVID-19 - A systematic review and meta-analysis of randomized controlled trials

Purpose

Favipiravir has been used in the therapy of COVID-19, including patients with mild to moderate symptoms in certain countries. The aim of our systematic review and meta-analysis was to investigate its efficacy and safety in mild-to-moderate COVID-19 infections.

Methods

The PubMed, Embase, Web of Science, and Cochrane databases were systematically reviewed for articles reporting the results of randomized controlled trials published until January 6, 2023, resulting in the identification of 20 eligible studies.

Results

There were no significant differences in viral clearance time (HR = 1.20, p = 0.09) compared to those without favipiravir therapy. However, in the subgroup analyses, favipiravir treatment significantly increased viral clearance by 59 % (HR = 1.59, p < 0.01) and 42 % (HR = 1.42, p < 0.01], I2 = 20 %) compared to the comparator group in patients with moderate severity of COVID-19 and in the inpatient care setting, respectively. Favipiravir had no beneficial effects in the case of patients with mild symptoms and treated in ambulatory care.

Conclusions

The use of favipiravir is questionable in the treatment of outpatients with COVID-19 with mild symptoms. Moderate beneficial effects in the case of patients with moderate symptoms and inpatients should be treated with care due to the limitations of the analysed trials.

A randomized trial to assess the acceleration of viral clearance by the combination Favipiravir/Ivermectin/Niclosamide in mild-to-moderate COVID-19 adult patients (FINCOV)

BACKGROUND

The efficacy of the viral clearance and clinical outcomes of favipiravir (FPV) in outpatients being treated for coronavirus disease 2019 (COVID-19) is unclear. Ivermectin (IVM), niclosamide (NCL), and FPV demonstrated synergistic effects in vitro for exceed 78% inhibiting severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) replication.

METHODS

A phase 2, open-label, 1:1, randomized, controlled trial was conducted on Thai patients with mild-to-moderate COVID-19 who received either combination FPV/IVM/NCL therapy or FPV alone to assess the rate of viral clearance among individuals with mild-to-moderate COVID-19.

RESULTS

Sixty non-high-risk comorbid patients with mild-to-moderate COVID-19 were randomized; 30 received FPV/IVM/NCL, and 30 received FPV alone. Mixed-effects multiple linear regression analysis of the cycle threshold value from SARS-CoV-2 PCR demonstrated no statistically significant differences in viral clearance rates between the combined FPV/IVM/NCL therapy group and the FPV-alone group. World Health Organization Clinical Progression scores and symptomatic improvement did not differ between arms on days 3, 6, and 10, and no adverse events were reported. No patients required hospitalization, intensive care unit admission, or supplemental oxygen or died within 28 days. C-reactive protein on day 3 was lower in the FPV/IVM/NCL group.

CONCLUSION

Viral clearance rates did not differ significantly between the FPV/IVM/NCL combination therapy and FPV-alone groups of individuals with mild-to-moderate COVID-19, although the combined regimen demonstrated a synergistic effect in vitro. No discernible clinical benefit was observed. Further research is required to explore the potential benefits of FVP beyond its antiviral effects.

TRIAL REGISTRATION

TCTR20230403007, Registered 3 April 2023 - Retrospectively registered,https://trialsearch.who.int/Trial2.aspx?TrialID=TCTR20230403007.

Favipiravir ameliorates bleomycin-induced pulmonary fibrosis by reprogramming M1/M2 macrophage polarization

Corona Virus Disease 2019 (COVID-19) is an infectious disease that seriously endangers human life and health. The pathological anatomy results of patients who died of the COVID-19 showed that there was an excessive inflammatory response in the lungs. It is also known that most of the COVID-19 infected patients will cause different degrees of lung damage after infection, and may have pulmonary fibrosis remaining after cure. Macrophages are a type of immune cell population with pluripotency and plasticity. In the early and late stages of infection, the dynamic changes of the balance and function of M1/M2 alveolar macrophages have a significant impact on the inflammatory response of the lungs. In the early stage of pulmonary fibrosis inflammation, the increase in the proportion of M1 type is beneficial to clear pathogenic microorganisms and promote the progress of inflammation; in the later stage of fibrosis, the increase in the number of M2 type macrophages can inhibit the inflammatory response and promote the degradation of fibrosis. As a potential treatment drug for new coronavirus pneumonia, favipiravir is in the process of continuously carried out relevant clinical trials. This study aims to discuss whether the antiviral drug favipiravir can suppress inflammation and immune response by regulating the M1/M2 type of macrophages, thereby alleviating fibrosis. We established a bleomycin-induced pulmonary fibrosis model, using IL-4/13 and LPS/IFN-γ cell stimulating factor to induce macrophage M1 and M2 polarization models, respectively. Our study shows that favipiravir exerts anti-fibrotic effects mainly by reprogramming M1/M2 macrophages polarization, that is, enhancing the expression of anti-fibrotic M1 type, reducing the expression of M2 type pro-fibrotic factors and reprogramming it to anti-fibrotic phenotype. Aspects of pharmacological mechanisms, favipiravir inhibits the activation of JAK2-STAT6 and JAK2-PI3K-AKT signaling by targeting JAK2 protein, thereby inhibiting pro-fibrotic M2 macrophages polarization and M2-induced myofibroblast activation. In summary, favipiravir can reduce the progression of pulmonary fibrosis, we hope to provide a certain reference for the treatment of pulmonary fibrosis.

Development of favipiravir dry powders for intranasal delivery: An integrated cocrystal and particle engineering approach via spray freeze drying

The therapeutic potential of pharmaceutical cocrystals in intranasal applications remains largely unexplored despite progressive advancements in cocrystal research. We present the application of spray freeze drying (SFD) in successful fabrication of a favipiravir-pyridinecarboxamide cocrystal nasal powder formulation for potential treatment of broad-spectrum antiviral infections. Preliminary screening via mechanochemistry revealed that favipiravir (FAV) can cocrystallize with isonicotinamide (INA), but not nicotinamide (NCT) and picolinamide (PIC) notwithstanding their structural similarity. The cocrystal formation was characterized by differential scanning calorimetry, Fourier-transform infrared spectroscopy, and unit cell determination through Rietveld refinement of powder X-ray analysis. FAV-INA crystalized in a monoclinic space group P21/c with a unit cell volume of 1223.54(3) Å3, accommodating one FAV molecule and one INA molecule in the asymmetric unit. The cocrystal was further reproduced as intranasal dry powders by SFD, of which the morphology, particle size, in vitro drug release, and nasal deposition were assessed. The non-porous flake shaped FAV-INA powders exhibited a mean particle size of 19.79 ± 2.61 μm, rendering its suitability for intranasal delivery. Compared with raw FAV, FAV-INA displayed a 3-fold higher cumulative fraction of drug permeated in Franz diffusion cells at 45 min (p = 0.001). Dose fraction of FAV-INA deposited in the nasal fraction of a customized 3D-printed nasal cast reached over 80 %, whereas the fine particle fraction remained below 6 % at a flow rate of 15 L/min, suggesting high nasal deposition whilst minimal lung deposition. FAV-INA was safe in RPMI 2650 nasal and SH-SY5Y neuroblastoma cells without any in vitro cytotoxicity observed. This study demonstrated that combining the merits of cocrystallization and particle engineering via SFD can propel the development of advanced dry powder formulations for intranasal drug delivery.

Evaluation of the Polysaccharide "Immeran" Activity in Syrian hamsters' Model of SARS-CoV-2

COVID-19 is a highly contagious respiratory disease with a high number of lethal cases in humans, which causes the need to search for new therapeutic agents. Polysaccharides could be one of the prospective types of molecules with a large variety of biological activities, especially antiviral. The aim of this work was to study the specific antiviral activity of the drug "Immeran" on a model of a new coronavirus infection SARS-CoV-2 in hamsters. Based on the second experiment, intraperitoneal treatment with the drug according to a treatment regimen in doses of 500 and 1000 μg/kg (administration after an hour, then once a day every other day, a total of 3 administrations) was effective, reliably suppressing the replication of the virus in the lungs and, at a dose of 1000 μg/kg, prevented weight loss in animals. In all cases, the treatment stimulated the formation of virus-neutralizing antibodies to the SARS-CoV-2 virus, which suggests that the drug possesses adjuvant properties.

Findings from a discontinued clinical trial of favipiravir in high-risk patients with early-onset COVID-19

INTRODUCTION

Favipiravir terminates severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) replication. Accordingly, early administration of favipiravir to SARS-CoV-2-infected coronavirus disease 2019 (COVID-19) patients may be expected to suppress disease progression.

METHODS

A randomized double-blind placebo-controlled trial was conducted to demonstrate efficacy of favipiravir in reducing disease progression in patients with mild COVID-19. The participants were unvaccinated patients with comorbidities and at risk of progression to severe disease. Patients were enrolled within 72 h of disease onset and randomized to receive either favipiravir (1800 mg/dose on Day 1 followed by 800 mg/dose) or matching placebo twice daily for 10 days. The primary endpoint was the proportion of patients requiring oxygen therapy within 28 days of randomization.

RESULTS

The trial was discontinued after enrolling 84 patients due to slower than anticipated enrollment caused by rapid uptake of SARS-CoV-2-vaccines and the emergence of the Omicron variant. Results from the 84 patients demonstrated no significant difference in all clinical outcomes. In post-hoc analyses, favipiravir treatment showed higher efficacy in patients within 48 h of onset. No deaths or severe adverse events were documented in the favipiravir group. Plasma concentrations of favipiravir from Day 2 onward were maintained above 40 μg/mL.

CONCLUSIONS

Conducting clinical trials for pathogens like SARS-CoV-2 that rapidly accumulate mutations leading to altered disease characteristics carries significant risks unless it can be done in a short period. Therefore, it would be important to prepare the comprehensive clinical trial platform that can appropriately and promptly evaluate drugs even under a pandemic.

Safety and efficacy of favipiravir in COVID-19 patients with pneumonia. A randomized, double-blind, placebo-controlled study (FAVID)

PURPOSE

To design a randomized clinical trial to assess the efficacy and safety of favipiravir in patients with COVID-19 disease with pneumonia.

METHODS

A randomized, double blind, placebo-controlled clinical trial of favipiravir in patients with COVID-19 pneumonia was conducted in three Spanish sites. Randomization 1:1 to favipiravir or placebo (in both groups added to the Standard of Care) was performed to treat the patients with COVID-19 pneumonia. The primary endpoint was "time to clinical improvement," measured as an improvement for ≥ two categories on a 7-point WHO ordinal scale in an up to 28 days' time frame.

RESULTS

Forty-four patients were randomized (23 in the favipiravir group and 21 in the placebo group). The median time to clinical improvement was not different between the favipiravir and the placebo arms (10 days for both groups) and none of the secondary endpoints showed significant differences between arms. The proportion of adverse events (both serious and non-serious) was statistically different between the favipiravir group (68.29%) and the placebo group (31.7%) (p = 0.019), but there was insufficient statistical evidence to correlate the degree of severity of the events with the treatment group.

CONCLUSIONS

Favipiravir administered for ten days to patients with COVID-19 and pneumonia did not improve outcomes compared with placebo. Although this is an underpowered negative study, efficacy results align with other randomized trials. However, in the present study, the non-serious adverse events were more frequent in the favipiravir group.

Favipiravir for treating COVID-19

BACKGROUND

The coronavirus disease 2019 (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) continues to challenge the health workforce and societies worldwide. Favipiravir was suggested by some experts to be effective and safe to use in COVID-19. Although this drug has been evaluated in randomized controlled trials (RCTs), it is still unclear if it has a definite role in the treatment of COVID-19.

OBJECTIVES

To assess the effects of favipiravir compared to no treatment, supportive treatment, or other experimental antiviral treatment in people with acute COVID-19.

SEARCH METHODS

We searched the Cochrane COVID-19 Study Register, MEDLINE, Embase, the World Health Organization (WHO) COVID-19 Global literature on coronavirus disease, and three other databases, up to 18 July 2023.

SELECTION CRITERIA

We searched for RCTs evaluating the efficacy of favipiravir in treating people with COVID-19.

DATA COLLECTION AND ANALYSIS

We used standard Cochrane methodological procedures for data collection and analysis. We used the GRADE approach to assess the certainty of evidence for each outcome.

MAIN RESULTS

We included 25 trials that randomized 5750 adults (most under 60 years of age). The trials were conducted in Bahrain, Brazil, China, India, Iran, Kuwait, Malaysia, Mexico, Russia, Saudi Arabia, Thailand, the UK, and the USA. Most participants were hospitalized with mild to moderate disease (89%). Twenty-two of the 25 trials investigated the role of favipiravir compared to placebo or standard of care, whilst lopinavir/ritonavir was the comparator in two trials, and umifenovir in one trial. Most trials (24 of 25) initiated favipiravir at 1600 mg or 1800 mg twice daily for the first day, followed by 600 mg to 800 mg twice a day. The duration of treatment varied from five to 14 days. We do not know whether favipiravir reduces all-cause mortality at 28 to 30 days, or in-hospital (risk ratio (RR) 0.84, 95% confidence interval (CI) 0.49 to 1.46; 11 trials, 3459 participants; very low-certainty evidence). We do not know if favipiravir reduces the progression to invasive mechanical ventilation (RR 0.86, 95% CI 0.68 to 1.09; 8 trials, 1383 participants; very low-certainty evidence). Favipiravir may make little to no difference in the need for admission to hospital (if ambulatory) (RR 1.04, 95% CI 0.44 to 2.46; 4 trials, 670 participants; low-certainty evidence). We do not know if favipiravir reduces the time to clinical improvement (defined as time to a 2-point reduction in patients' admission status on the WHO's ordinal scale) (hazard ratio (HR) 1.13, 95% CI 0.69 to 1.83; 4 trials, 721 participants; very low-certainty evidence). Favipiravir may make little to no difference to the progression to oxygen therapy (RR 1.20, 95% CI 0.83 to 1.75; 2 trials, 543 participants; low-certainty evidence). Favipiravir may lead to an overall increased incidence of adverse events (RR 1.27, 95% CI 1.05 to 1.54; 18 trials, 4699 participants; low-certainty evidence), but may result in little to no difference inserious adverse eventsattributable to the drug (RR 1.04, 95% CI 0.76 to 1.42; 12 trials, 3317 participants; low-certainty evidence).

AUTHORS' CONCLUSIONS

The low- to very low-certainty evidence means that we do not know whether favipiravir is efficacious in people with COVID-19 illness, irrespective of severity or admission status. Treatment with favipiravir may result in an overall increase in the incidence of adverse events but may not result in serious adverse events.

Off-label Use of Medicines in COVID-19: A Lesson For Future

Abstract:

The COVID-19 infection is rapidly spreading worldwide. Treating this new viral infection is a great challenge worldwide. There is no specific and approved medication for its treatment, so some medications are considered off-label. Antivirals, corticosteroids, antimalarial agents, and antibiotics are proposed in different countries to treat COVID-19. This narrative review discussed the off-label use of medications for COVID-19 and the beneficial and adverse effects of them. Evidence was collected and sorted from the literature ranging from 2019 to 2022 on scientific databases such as Web of Science, PubMed, and Scopus with suitable keywords. All papers, namely systematic reviews, case studies, and clinical guidelines, were evaluated. Antimalarial agents, antivirals, antibiotics, corticosteroids, NSAIDs, biological medicines, Ivermectin, and melatonin were reviewed in this study. Some medications have direct antiviral effects, and many can reduce infection symptoms and hospitalization. In some clinical trial trials, even some of them, such as corticosteroids, can lower death rates, particularly during the cytokine storm period. However, the effectiveness of some medications has not been understood. Besides, the side effects of off-label use of these medications must be considered a serious concern. There are no proven medications for COVID-19 yet. Off-label use of medications is a double-edged sword that can have advantages outweighing its disadvantages. The COVID-19 crisis taught us many lessons about dealing with health-related crises and their treatment management. One of the most important lessons is paying more attention to the discovery and development of novel drugs and vaccines based on modern technology.

Clinical antiviral efficacy of favipiravir in early COVID-19 (PLATCOV): an open-label, randomised, controlled, adaptive platform trial

In early symptomatic COVID-19 treatment, high dose oral favipiravir did not accelerate viral clearance.

BACKGROUND

Favipiravir, an anti-influenza drug, has in vitro antiviral activity against SARS-CoV-2. Clinical trial evidence to date is inconclusive. Favipiravir has been recommended for the treatment of COVID-19 in some countries.

METHODS

In a multicentre open-label, randomised, controlled, adaptive platform trial, low-risk adult patients with early symptomatic COVID-19 were randomised to one of ten treatment arms including high dose oral favipiravir (3.6g on day 0 followed by 1.6g daily to complete 7 days treatment) or no study drug. The primary outcome was the rate of viral clearance (derived under a linear mixed-effects model from the daily log10 viral densities in standardised duplicate oropharyngeal swab eluates taken daily over 8 days [18 swabs per patient]), assessed in a modified intention-to-treat population (mITT). The safety population included all patients who received at least one dose of the allocated intervention. This ongoing adaptive platform trial was registered at ClinicalTrials.gov (NCT05041907) on 13/09/2021.

RESULTS

In the final analysis, the mITT population contained data from 114 patients randomised to favipiravir and 126 patients randomised concurrently to no study drug. Under the linear mixed-effects model fitted to all oropharyngeal viral density estimates in the first 8 days from randomisation (4,318 swabs), there was no difference in the rate of viral clearance between patients given favipiravir and patients receiving no study drug; a -1% (95% credible interval: -14 to 14%) difference. High dose favipiravir was well-tolerated.

INTERPRETATION

Favipiravir does not accelerate viral clearance in early symptomatic COVID-19. The viral clearance rate estimated from quantitative measurements of oropharyngeal eluate viral densities assesses the antiviral efficacy of drugs in vivo with comparatively few studied patients.

An Update on SARS-CoV-2 Clinical Trial Results-What We Can Learn for the Next Pandemic

The coronavirus disease 2019 (COVID-19) pandemic has claimed over 7 million lives worldwide, providing a stark reminder of the importance of pandemic preparedness. Due to the lack of approved antiviral drugs effective against coronaviruses at the start of the pandemic, the world largely relied on repurposed efforts. Here, we summarise results from randomised controlled trials to date, as well as selected in vitro data of directly acting antivirals, host-targeting antivirals, and immunomodulatory drugs. Overall, repurposing efforts evaluating directly acting antivirals targeting other viral families were largely unsuccessful, whereas several immunomodulatory drugs led to clinical improvement in hospitalised patients with severe disease. In addition, accelerated drug discovery efforts during the pandemic progressed to multiple novel directly acting antivirals with clinical efficacy, including small molecule inhibitors and monoclonal antibodies. We argue that large-scale investment is required to prepare for future pandemics; both to develop an arsenal of broad-spectrum antivirals beyond coronaviruses and build worldwide clinical trial networks that can be rapidly utilised.

[The effect of etiopathogenetic therapy of COVID-19 on the severity of the disease: results of a multicenter double-blind placebo-controlled randomized trial]

AIM

The search for etiopathogenetic agents to prevent the development of severe and extremely severe COVID-19 remains relevant. A placebo-controlled randomized clinical trial was conducted to evaluate the efficacy and safety of the antibody-based biological drug (Raphamin).

MATERIALS AND METHODS

785 outpatients 18-75 y.o. with laboratory confirmed mild COVID-19 were included within 24 hours from the disease onset. 771 patients were randomized to the group Raphamin (n=382) and the Placebo group (n=389). The study drug/placebo was prescribed for 5 days. The rate of progression to a more severe degree of COVID-19 by day 28 as well as the time to sustained clinical recovery and the frequency of hospitalization were evaluated. Safety was assessed taking into account adverse events, vital signs and laboratory parameters.

RESULTS

The number of cases of progression to a more severe degree of COVID-19 in participants receiving Raphamin was 59 (15.5%) [52 (14.6%)] versus placebo - 89 (22.9%) [85 (23.7%)], ITT and [PP] analysis data are presented. The odds ratio between groups was OR=0.6157 [OR=0.5494], 95% confidence interval 0.4276-0.8866 [0.3750-0.8048], which meant a reduction in the chance of progression to a more severe degree by 38.4% [45.1%] or 1.48 [1.62] times; p=0.0088 [p=0.0019]. The time to sustained recovery in the Raphamin group was 4.5±2.4 [4.6±2.4] days, versus placebo - 5.8±4.7 [6.0±4.8] days; p=0.0025 [p=0.0036]. No adverse events with a certain relationship were registered.

CONCLUSION

Raphamin reduces the risk of progression to a more severe degree of the COVID-19 and significantly shortens the duration of clinical symptoms.

Clinical development of antivirals against SARS-CoV-2 and its variants

The unceasing global spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) calls for the development of novel therapeutics. Although many newly developed antivirals and repurposed antivirals have been applied to the treatment of coronavirus disease 2019 (COVID-19), antivirals showing satisfactory clinical efficacy are few in number. In addition, the loss of sensitivity to variants of concern (VOCs) and lack of oral bioavailability have also limited the clinical application of some antivirals. These facts remind us to develop more potent and broad-spectrum antivirals with better pharmacokinetic/pharmacodynamic properties to fight against infections from SARS-CoV-2, its variants, and other human coronaviruses (HCoVs). In this review, we summarize the latest advancements in the clinical development of antivirals against infections by SARS-CoV-2 and its variants.

The Functional Implications of Broad Spectrum Bioactive Compounds Targeting RNA-Dependent RNA Polymerase (RdRp) in the Context of the COVID-19 Pandemic

BACKGROUND

As long as COVID-19 endures, viral surface proteins will keep changing and new viral strains will emerge, rendering prior vaccines and treatments decreasingly effective. To provide durable targets for preventive and therapeutic agents, there is increasing interest in slowly mutating viral proteins, including non-surface proteins like RdRp.

METHODS

A scoping review of studies was conducted describing RdRp in the context of COVID-19 through MEDLINE/PubMed and EMBASE. An iterative approach was used with input from content experts and three independent reviewers, focused on studies related to either RdRp activity inhibition or RdRp mechanisms against SARS-CoV-2.

RESULTS

Of the 205 records screened, 43 studies were included in the review. Twenty-five evaluated RdRp activity inhibition, and eighteen described RdRp mechanisms of existing drugs or compounds against SARS-CoV-2. In silico experiments suggested that RdRp inhibitors developed for other RNA viruses may be effective in disrupting SARS-CoV-2 replication, indicating a possible reduction of disease progression from current and future variants. In vitro, in vivo, and human clinical trial studies were largely consistent with these findings.

CONCLUSIONS

Future risk mitigation and treatment strategies against forthcoming SARS-CoV-2 variants should consider targeting RdRp proteins instead of surface proteins.

Efficacy and safety of molnupiravir in patients with Omicron variant vaccine breakthrough COVID-19 infection: a randomized, controlled trial

Introduction: Randomized, controlled trials of molnupiravir in real-world use during the Omicron wave are scarce. The frequency of hospitalization and death is low, so further research is needed to confirm the virological efficacy of molnupiravir. Methods: A single-center, randomized, controlled clinical trial was conducted, and 111 hospitalized coronavirus disease 2019 (COVID-19) patients were randomly assigned at a ratio of 1:1. Fifty-three patients in the molnupiravir group were administered 800 mg of molnupiravir twice daily for 5 days in addition to the standard therapy, and 58 patients in the control group only received the standard therapy in accordance with local guidelines. The antiviral effect and adverse events were evaluated during the follow-up. Results: The median viral clearance time in the molnupiravir group was significantly shorter than that in the control group (p = 0.003). Furthermore, patients who started molnupiravir therapy within 3 days had significantly shorter viral clearance time than the controls (p = 0.003). In the vaccinated subgroup, molnupiravir therapy was also associated with a shorter viral clearance time (p = 0.003). A total of three adverse events, which were minor, were reported in the molnupiravir group. One of the patients had mild liver function abnormalities, and all of them were resolved without intervention. However, the remission time was similar between the two tested groups. Conclusion: Molnupiravir exhibited good viral replication inhibitor efficacy in patients with Omicron variant vaccine breakthrough COVID-19 infection. Clinical Trial Registration: [https://www.chictr.org.cn/], identifier [ChiCTR2200059796].

Ayurveda-based phytochemical composition attenuates lung inflammation and precipitates pharmacokinetic interaction with favipiravir: an in vivo investigation using disease-state of acute lung injury

Acute respiratory distress syndrome (ARDS) is a critical form of acute lung injury (ALI). Here, we investigated the effect of a defined combination of ten pure phytochemicals in equal proportions of weight (NPM) from plants, recommended by Ayurveda for any protective action against lipopolysaccharide (LPS)-induced ALI. Results indicate that NPM markedly improved protein and neutrophil contents, myeloperoxidase and hydroxyproline levels, oxidative stress markers (glutathione and malonaldehyde), inflammatory cytokines, and genes (IL-6, TNF-α, TGF-β, and NF-κB/IκBα) in BALF/lung tissue. The histopathological examination of the lung revealed the shielding effect of NPM against ALI. NPM exhibited a protective effect on the lung by reducing oxidative stress and inhibiting inflammation. A substantial drop in favipiravir's oral exposure was observed in ALI-state compared to normal-state, but oral exposure upon NPM treatment in ALI-state followed similar behaviour of favipiravir alike normal-state without NPM treatment. Overall, results offer potential insight into Ayurvedic recommendations for immunity boosting during ALI situations.

Clinical manifestations and outcomes of coronavirus disease 2019 among pediatric liver transplant recipients in the delta and omicron variant pandemic: A retrospective study

To determine the clinical manifestations and outcomes of the coronavirus disease 2019 (COVID-19) in children who underwent liver transplantation (LT). A retrospective study was conducted at a transplant center in Thailand to include LT recipients aged < 18 years who had been infected with COVID-19. Out of a total of 54 children, there were 31 probable cases (57.4%) diagnosed using an antigen test kit and 23 confirmed cases (42.6%) diagnosed using polymerase chain reaction (14 children) or severe acute respiratory syndrome coronavirus 2 antigen (9 children). Approximately half of the children (25, 46.3%) received the BNT162b2 vaccine before the infection, with 3 and 2 doses in 5 and 18 children, respectively. While some had COVID-19 during the delta pandemic, most (46 children, 85.2%) were infected during the omicron pandemic, of which manifestations included fever (67.4%), cough (50%), and rhinorrhea (47.8%), and symptoms lasted approximately 3 days. None had severe diseases. All patients with mild-to-moderate disease were advised to continue the same immunosuppressive therapy as before the infection. Compared to unvaccinated children or children with one dose of the vaccine, fever was less common in those who received ≥ 2 doses (OR: 0.08; 95%CI: 0.01-0.57, adjusted for age and immunosuppressive types). Favipiravir was prescribed in most patients (90.7%). Only a few children had long COVID-19 or abnormal liver function tests lasting > 1 month (4 children, 7.4%, both). Pediatric LT recipients with COVID-19 during the delta and omicron variant pandemic reported mild symptoms despite undergoing immunosuppressive therapy.

Efficacy of Andrographis paniculata extract treatment in mild to moderate COVID-19 patients being treated with favipiravir: A double-blind, randomized, placebo-controlled study (APFaVi trial)

BACKGROUND

While favipiravir had been the standard anti-SARS-CoV-3 drug for COVID-19 treatment in Thailand, the efficacy of favipiravir treatment is controversial. Andrographis paniculata extract (APE) inhibits viral entry, exhibits immunomodulatory effects, and proposes to have the potential for early-stage COVID-19 treatment.

METHODS

A randomized, double-blind, placebo-controlled trial was performed in Thailand during June - September 2021. Non-severe COVID-19 patients were randomized 1:1 to groups receiving 180 mg/day of APE plus favipiravir (APE-FPV group) or placebo plus favipiravir (placebo-FPV group). Efficacy in preventing disease progression to severe COVID-19 was assessed on day 4, using World Health Organization Clinical Progression Scale (WHOCPS) score and visual analog scale (VAS) for acute respiratory tract infection symptoms.

RESULTS

Of 146 patients, there were 73 patients in each group. Non-deterioration of WHOCPS scores on day 4 was 98.63% versus 97.26% of patients in the APE-FPV and placebo-FPV groups (p = 1.000). No difference in supplemental oxygen, hospitalization, and death was shown in both groups. The oxygen supplemental was 4.11% in the placebo-FPV group. The interleukin (IL)-1β was significantly lower in the APE than in the placebo-FPV group throughout the study. We found no difference in virologic outcomes between groups and no substantial adverse events.

CONCLUSIONS

APE treatment did not demonstrate additional clinical and virological benefits in patients with mild to moderate COVID-19 being treated with favipiravir. Early reduction of IL-1β with APE may be advantageous in preventing cytokine storms in severe COVID-19 and requires further study.

Favipiravir treatment in non-severe COVID-19: promising results from multicenter propensity score-matched study (FAVICOV)

This study aimed to evaluate the efficacy of favipiravir (FPV) in preventing the development of severe COVID-19 in patients with mild-to-moderate symptoms. The study evaluated 1037 COVID-19 patients treated with FPV or standard treatment between April and September 2021, analyzed by propensity score matching. 149 patients were included in each arm after propensity score matching. The clinical outcomes showed no deterioration of the WHO clinical progression scale in the FPV group compared to the standard treatment group on day 5 (83.2% vs. 69.1%, p < 0.001). The WHO clinical progression scale also showed improvements on day 14 in the FPV group compared to the standard treatment group (66.4% vs. 46.3%, p < 0.001). The rates of oxygen supplementation and hospitalization were significantly lower in the FPV group compared to the standard treatment group (0% vs. 12.1% and 0.7% vs. 17.4%, respectively, p < 0.001 for both). There were no differences in adverse events between the two groups. The study highlights the effectiveness of FPV in preventing severe COVID-19 and hospitalization in patients with mild-to-moderate symptoms. The findings emphasize the importance of personalized treatment plans for COVID-19 patients, starting FPV treatment early, and adjusting dosages based on ethnicity and body weight.

The Real-World Clinical Outcomes of Favipiravir Treatment with Telemedicine Monitoring in Preventing Disease Progression in Mild to Moderate COVID-19 Patients; A Retrospective Cohort Study

Background: Favipiravir has complex pharmacokinetics, and varied efficacy has been reported in treating COVID-19. Telehealth and telemonitoring are disruptive challenges used for COVID-19 care during pandemics. Objective: This study aimed to assess the outcome of favipiravir treatment to prevent clinical deterioration in mild to moderate COVID-19 cases with adjunctive telemonitoring during the COVID-19 surge. Methods: This was a retrospective observational study of PCR-confirmed mild to moderate COVID-19 cases subjected to home isolation. Chest computed tomography (CT) was performed in all cases, and favipiravir was administrated. Results: This study involved 88 PCR-confirmed COVID-19 cases. In addition, 42/42 (100%) cases were Alpha variants. COVID-19 pneumonia was found in 71.5% of the cases, according to chest X-rays and chest CT on the first visit. Favipiravir started 4 days after symptoms, which was part of the standard of care. The 12.5% of the patients required supplemental oxygen and intensive care unit admission rate was 1.1%; 1.1% required mechanical ventilation, and the rate of all-cause mortality was 1.1%, with a value of 0% of severe COVID-19 deaths. All mild illness cases showed no clinical deterioration or requirement for supplemental oxygen. No significant deterioration in either obesity or diabetes mellitus was observed. Conclusions: Favipiravir treatment for mild to moderate COVID-19 cases in outpatient settings, coupled with telemonitoring, was both safe and effective in preventing clinical deterioration, including the need for oxygen supplementation. This approach proved valuable during surges of COVID-19 cases.

Drug repositioning in the COVID-19 pandemic: fundamentals, synthetic routes, and overview of clinical studies

INTRODUCTION

Drug repositioning is a strategy to identify a new therapeutic indication for molecules that have been approved for other conditions, aiming to speed up the traditional drug development process and reduce its costs. The high prevalence and incidence of coronavirus disease 2019 (COVID-19) underline the importance of searching for a safe and effective treatment for the disease, and drug repositioning is the most rational strategy to achieve this goal in a short period of time. Another advantage of repositioning is the fact that these compounds already have established synthetic routes, which facilitates their production at the industrial level. However, the hope for treatment cannot allow the indiscriminate use of medicines without a scientific basis.

RESULTS

The main small molecules in clinical trials being studied to be potentially repositioned to treat COVID-19 are chloroquine, hydroxychloroquine, ivermectin, favipiravir, colchicine, remdesivir, dexamethasone, nitazoxanide, azithromycin, camostat, methylprednisolone, and baricitinib. In the context of clinical tests, in general, they were carried out under the supervision of large consortiums with a methodology based on and recognized in the scientific community, factors that ensure the reliability of the data collected. From the synthetic perspective, compounds with less structural complexity have more simplified synthetic routes. Stereochemical complexity still represents the major challenge in the preparation of dexamethasone, ivermectin, and azithromycin, for instance.

CONCLUSION

Remdesivir and baricitinib were approved for the treatment of hospitalized patients with severe COVID-19. Dexamethasone and methylprednisolone should be used with caution. Hydroxychloroquine, chloroquine, ivermectin, and azithromycin are ineffective for the treatment of the disease, and the other compounds presented uncertain results. Preclinical and clinical studies should not be analyzed alone, and their methodology's accuracy should also be considered. Regulatory agencies are responsible for analyzing the efficacy and safety of a treatment and must be respected as the competent authorities for this decision, avoiding the indiscriminate use of medicines.

Phase II, Double-Blinded, Randomized, Placebo-Controlled Clinical Trial Investigating the Efficacy of Mebendazole in the Management of Symptomatic COVID-19 Patients

The outbreak of the COVID-19 pandemic has spread throughout the world, affecting almost all nations and territories. The current double-blind, randomized, placebo-controlled, phase II clinical trial sought to evaluate the clinical efficacy and safety of mebendazole as an adjuvant therapy for outpatients with COVID-19. The patients were recruited and divided into two groups: a Mebendazole-treated group and placebo group. The mebendazole and placebo groups were matched for age, sex, and complete blood count (CBC) with differential and liver and kidney function tests at baseline. On the third day, the C-reactive protein (CRP) levels were lower (2.03 ± 1.45 vs. 5.45 ± 3.95, p < 0.001) and the cycle threshold (CT) levels were higher (27.21 ± 3.81 vs. 24.40 ± 3.09, p = 0.046) significantly in the mebendazole group than in the placebo group on the third day. Furthermore, CRP decreased and CT dramatically increased on day three compared to the baseline day in the mebendazole group (p < 0.001 and p = 0.008, respectively). There was a significant inverse correlation between lymphocytes and CT levels in the mebendazole group (r = -0.491, p = 0.039) but not in the placebo group (r = 0.051, p = 0.888). Mebendazole therapy increased innate immunity and returned inflammation to normal levels in COVID-19 outpatients faster than it did in the placebo group in this clinical trial. Our findings add to the growing body of research on the clinical and microbiological benefits of repurposing antiparasitic therapy, specifically mebendazole, for SARS-CoV-2 infection and other viral infections.

Revealing the structural and molecular interaction landscape of the favipiravir-RTP and SARS-CoV-2 RdRp complex through integrative bioinformatics: Insights for developing potent drugs targeting SARS-CoV-2 and other viruses

BACKGROUND

The global research community has made considerable progress in therapeutic and vaccine research during the COVID-19 pandemic. Several therapeutics have been repurposed for the treatment of COVID-19. One such compound is, favipiravir, which was approved for the treatment of influenza viruses, including drug-resistant influenza. Despite the limited information on its molecular activity, clinical trials have attempted to determine the effectiveness of favipiravir in patients with mild to moderate COVID-19. Here, we report the structural and molecular interaction landscape of the macromolecular complex of favipiravir-RTP and SARS-CoV-2 RdRp with the RNA chain.

METHODS

Integrative bioinformatics was used to reveal the structural and molecular interaction landscapes of two macromolecular complexes retrieved from RCSB PDB.

RESULTS

We analyzed the interactive residues, H-bonds, and interaction interfaces to evaluate the structural and molecular interaction landscapes of the two macromolecular complexes. We found seven and six H-bonds in the first and second interaction landscapes, respectively. The maximum bond length is 3.79 Å. In the hydrophobic interactions, five residues (Asp618, Asp760, Thr687, Asp623, and Val557) were associated with the first complex and two residues (Lys73 and Tyr217) were associated with the second complex. The mobilities, collective motion, and B-factor of the two macromolecular complexes were analyzed. Finally, we developed different models, including trees, clusters, and heat maps of antiviral molecules, to evaluate the therapeutic status of favipiravir as an antiviral drug.

CONCLUSIONS

The results revealed the structural and molecular interaction landscape of the binding mode of favipiravir with the nsp7-nsp8-nsp12-RNA SARS-CoV-2 RdRp complex. Our findings can help future researchers in understanding the mechanism underlying viral action and guide the design of nucleotide analogs that mimic favipiravir and exhibit greater potency as antiviral drugs against SARS-CoV-2 and other infectious viruses. Thus, our work can help in preparing for future epidemics and pandemics.

Evaluation of the toxicological effects of favipiravir (T-705) on liver and kidney in rats: biochemical and histopathological approach

Favipiravir is a selective RNA polymerase inhibitor and a broad-spectrum antiviral drug, an important agent used in viral infections, including Ebola, Lassa, and COVID-19. This study aims to evaluate the potential toxicological effects of favipiravir administration on rats' liver and kidney tissues. Favipiravir was applied for five and ten days in the present study. During this period, it was aimed to determine possible toxic effects on the liver and kidney. For this purpose, the impact of favipiravir on liver and kidney tissues were examined using histopathologic and biochemical methods. The present study showed that favipiravir administration led to an elevation in the liver and kidney serum enzymes and oxidative and histopathologic damages. Favipiravir administration caused apoptotic cell death (Caspase-3 and Bcl-2), inflammation (NF-κB and IL-6), and a decrease in renal reabsorption (AQP2) levels. In the evaluation of the findings obtained in this study, it was determined that the favipiravir or metabolites caused liver and kidney damages.

Does the Ethnic Difference Affect the Pharmacokinetics of Favipiravir? A Pharmacokinetic Study in Healthy Egyptian Volunteers and Development of Level C In-vitro In-vivo Correlation

Favipiravir is an antiviral drug used to treat influenza and is also being investigated for the treatment of SARS-CoV-2. Its pharmacokinetic profile varies depending on ethnic group. The present research examines the pharmacokinetic features of favipiravir in healthy male Egyptian volunteers. Another goal of this research is to determine the optimum dissolution testing conditions for immediate release tablets. In vitro dissolution testing was investigated for favipiravir tablets in three different pH media. The pharmacokinetic features of favipiravir were examined in 27 healthy male Egyptian volunteers. The parameter "AUC0-t" vs. percent dissolved was used to develop level C in vitro in vivo correlation (IVIVC) to set the optimum dissolution medium to achieve accurate dissolution profile for favipiravir (IR) tablets. The in vitro release results revealed significant difference among the three different dissolution media. The Pk parameters of twenty-seven human subjects showed mean value of Cpmax of 5966.45 ng/mL at median tmax of 0.75 h with AUC0-∞ equals 13325.54 ng.h/mL, showing half-life of 1.25 h. Level C IVIVC was developed successfully. It was concluded that Egyptian volunteers had comparable Pk values to American and Caucasian volunteers, however they were considerably different from Japanese subjects. AUC0-t vs. % dissolved was used to develop level C IVIVC to set the optimum dissolution medium. Phosphate buffer medium (pH 6.8) was found to be the optimum dissolution medium for in vitro dissolution testing for Favipiravir IR tablets.

Use of anti-viral therapies in hospitalised COVID-19 patients in the United Arab Emirates: a cost-effectiveness and health-care resource use analysis

BACKGROUND

This study attempts to estimate the cost-effectiveness of the antiviral remdesivir, as recommended in the 2021 COVID treatment guidelines for the United Arab Emirates, compared to standard of care (SOC), but also favipiravir (FAVI), which was also recommended for the treatment of hospitalized COVID patients.

METHODS

A cost-effectiveness model was built using published efficacy data for RDV, FAVI and SOC as well as local epidemiology data. The outcomes measured included hospital bed days averted, mortality, costs and cost per outcome over one year. One-way, probabilistic and scenario analyses were undertaken to reflect uncertainty in the estimates.

RESULTS

When modelled over one year, the results indicated that treatment of adults in need of supplemental oxygen with RDV + SOC could result in 11,338 fewer general ward bed days, 7,003 fewer ICU days and 5,451 fewer ICU + MIV bed days compared to SOC alone and similar results when compared with FAVI + SOC. The model results also showed that there were 374 fewer deaths associated with the use of RDV + SOC compared to SOC alone. The model also estimates substantial potential cost-savings associated with RDV + SOC treatment compared with SOC alone (USD 3,454 per patient). The results of the one-way sensitivity analysis showed that the model was sensitive to estimates of length of stay and the cost of hospitalization. Despite this, the model predicted cost-savings in all scenarios versus all comparators.

CONCLUSIONS

The model estimated that using RDV + SOC could result in substantial reductions in HCRU and cost savings regardless of the comparator. However, it should be noted that reliable clinical information on FAVI was limited therefore it is challenging to interpret these results. All the potential benefits modelled here for RDV + SOC can have implications not only for the health of the UAE population but for improving hospital capacity to deal with other conditions.

Severe COVID-19: Drugs and Clinical Trials

By January of 2023, the COVID-19 pandemic had led to a reported total of 6,700,883 deaths and 662,631,114 cases worldwide. To date, there have been no effective therapies or standardized treatment schemes for this disease; therefore, the search for effective prophylactic and therapeutic strategies is a primary goal that must be addressed. This review aims to provide an analysis of the most efficient and promising therapies and drugs for the prevention and treatment of severe COVID-19, comparing their degree of success, scope, and limitations, with the aim of providing support to health professionals in choosing the best pharmacological approach. An investigation of the most promising and effective treatments against COVID-19 that are currently available was carried out by employing search terms including "Convalescent plasma therapy in COVID-19" or "Viral polymerase inhibitors" and "COVID-19" in the Clinicaltrials.gov and PubMed databases. From the current perspective and with the information available from the various clinical trials assessing the efficacy of different therapeutic options, we conclude that it is necessary to standardize certain variables-such as the viral clearance time, biomarkers associated with severity, hospital stay, requirement of invasive mechanical ventilation, and mortality rate-in order to facilitate verification of the efficacy of such treatments and to better assess the repeatability of the most effective and promising results.

Potential RNA-dependent RNA polymerase (RdRp) inhibitors as prospective drug candidates for SARS-CoV-2

The SARS-CoV-2 pandemic is considered as one of the most disastrous pandemics for human health and the world economy. RNA-dependent RNA polymerase (RdRp) is one of the key enzymes that control viral replication. RdRp is an attractive and promising therapeutic target for the treatment of SARS-CoV-2 disease. It has attracted much interest of medicinal chemists, especially after the approval of Remdesivir. This study highlights the most promising SARS-CoV-2 RdRp repurposed drugs in addition to natural and synthetic agents. Although many in silico predicted agents have been developed, the lack of in vitro and in vivo experimental data has hindered their application in drug discovery programs.

Potential Anti-SARS-CoV-2 Prodrugs Activated by Phosphorylation and Their Role in the Aged Population

The COVID-19 pandemic has flared across every part of the globe and affected populations from different age groups differently. People aged from 40 to 80 years or older are at an increased risk of morbidity and mortality due to COVID-19. Therefore, there is an urgent requirement to develop therapeutics to decrease the risk of the disease in the aged population. Over the last few years, several prodrugs have demonstrated significant anti-SARS-CoV-2 effects in in vitro assays, animal models, and medical practice. Prodrugs are used to enhance drug delivery by improving pharmacokinetic parameters, decreasing toxicity, and attaining site specificity. This article discusses recently explored prodrugs such as remdesivir, molnupiravir, favipiravir, and 2-deoxy-D-glucose (2-DG) and their implications in the aged population, as well as investigating recent clinical trials.

Comprehensive evaluation of six interventions for hospitalized patients with COVID-19: A propensity score matching study

Purpose

The purpose of this study was to evaluate the effectiveness of either hydroxychloroquine, triple combination therapy (TCT), favipiravir, dexamethasone, remdesivir, or COVID-19 convalescent plasma (CCP) in comparison with standard-of-care for hospitalized patients with COVID-19 using real-world data from Saudi Arabia.

Patients and methods

A secondary database analysis was conducted using the Saudi Ministry of Health database for patients with COVID-19. Adult (≥ 18 years) hospitalized patients with COVID-19 between March 2020 and January 2021 were included in the analysis. A propensity score matching technique was used to establish comparable groups for each therapeutic approach. Lastly, an independent t-test and chi-square test were used to compare the matching groups in the aspects of the duration of hospitalization, length of stay (LOS) in intensive care units (ICU), in-hospital mortality, and composite poor outcome. Multilevel logistic regression model was used to assess the association between the severity stage of COVID-19 and the outcomes while using the medication or intervention used as a grouping variable in the model.

Results

The mean duration of hospitalization was significantly longer for patients who received TCT, favipiravir, dexamethasone, or CCP compared to patients who did not receive these therapies, with a mean difference ranging between 2.2 and 4.9 days for dexamethasone and CCP, respectively. Furthermore, the use of favipiravir or CCP was associated with a longer stay in ICU. Remdesivir was the only agent associated with in-hospital mortality benefit. A higher risk of mortality and poorer composite outcome were associated with the use of favipiravir or dexamethasone. However, the logistic regression model reveled that the difference between the two matched cohorts was due to the severity stage not the medication. Additionally, the use of hydroxychloroquine, TCT, or CCP had no impact on the incidence of in-hospital mortality or composite poor outcomes.

Conclusion

Remdesivir was the only agent associated with in-hospital mortality benefit. The observed worsened treatment outcomes associated with the use of dexamethasone or FPV shall be attributed to the severity stage rather than the medication use. In light of these varied results, additional studies are needed to continue evaluating the actual benefits of these therapies.

An overview on the treatments and prevention against COVID-19

BACKGROUND

The coronavirus disease 2019 (COVID-19) caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) continues to plague the world. While COVID-19 is asymptomatic in most individuals, it can cause symptoms like pneumonia, ARDS (acute respiratory distress syndrome), and death in others. Although humans are currently being vaccinated with several COVID-19 candidate vaccines in many countries, however, the world still is relying on hygiene measures, social distancing, and approved drugs.

RESULT

There are many potential therapeutic agents to pharmacologically fight COVID-19: antiviral molecules, recombinant soluble angiotensin-converting enzyme 2 (ACE2), monoclonal antibodies, vaccines, corticosteroids, interferon therapies, and herbal agents. By an understanding of the SARS-CoV-2 structure and its infection mechanisms, several vaccine candidates are under development and some are currently in various phases of clinical trials.

CONCLUSION

This review describes potential therapeutic agents, including antiviral agents, biologic agents, anti-inflammatory agents, and herbal agents in the treatment of COVID-19 patients. In addition to reviewing the vaccine candidates that entered phases 4, 3, and 2/3 clinical trials, this review also discusses the various platforms that are used to develop the vaccine COVID-19.

Effectiveness of Favipiravir monotherapy in the treatment of COVID-19: Real world data analysis from Thailand

Background

Previous studies showed that Favipiravir, a selective viral ribonucleic acid dependent-ribonucleic acid polymerase inhibitor, exhibited a trend of clinical improvement within 14 days and promoted viral clearance by day 7, without reduction of mortality rate in COVID-19.

Methods

During the COVID-19 pandemic, Department of Medical Services (Thailand) formulated National Clinical Treatment Guidelines for COVID-19 and approved Favipiravir to eight medical centres. After treatment with Favipiravir monotherapy, we compared real-world data analysis to supportive treatment without antiviral agents.

Findings

We analysed 12,888 COVID-19 patients between June 1, 2021, and July 31, 2021. This group study excluded 66 asymptomatic and 4,634 COVID-19 patients treated with other antiviral agents. The 4,896 mild, 2,357 moderate, and 1,393 severe COVID-19 patients were analysed. All patients neither had previous SARS-CoV-2 infection nor received an mRNA vaccine during study period. Favipiravir monotherapy reduced the 28-day mortality risk in severe COVID-19 by relative risk (RR) = 0.72 (95% CI 0.58-0.91 P=0.006) after adjustment for aging and hypertension. However, in mild and moderate COVID-19, Favipiravir monotherapy did not significantly reduce 28-day mortality risk by RR = 0.59 (95% CI 0.06- 5.43 P=0.65) after adjustment for aging, and RR = 0.60 (95% CI 0.32-1.13 P=0.11) after adjustment for aging and obesity, respectively. In the patient with recovery, Favipiravir monotherapy exhibited a shortening time to recovery when compared to supportive treatment without antiviral agents (mean + SD by 9.6+ 7.1 vs. 12.9 +7.6 days: P<0.0001, 10.0+5.9 vs. 12.4 + 5.3 days: P<0.0001, and 11.2 +7.8 vs. 13.1+ 8.0 days: P<0.0001 in mild, moderate, and severe COVID-19 respectively).

Interpretation

Real-world data analysis showed that favipiravir monotherapy was superior to supportive treatment without antiviral agents in shortening the recovery time in surviving patients and significantly reducing 28-day mortality risk in severe COVID-19.

Funding

Department of Medical Services, Ministry of Public Health, Thailand.