Remdesivir for Treatment of COVID-19: Combination of Pulmonary and IV Administration May Offer Aditional Benefit

Eco-Friendly Synchronous Spectrofluorimetric Method for Simultaneous Determination of Remdesivir and Acetyl Salicylic Acid in Spiked Human Plasma

Remdesivir and acetyl salicylic acid are often co-administered medications in the treatment of COVID-19, specifically targeting the viral infection and thromboembolism associated with the condition. Hence, it is essential to establish a technique that enables the concurrent quantification of these pharmaceutical compounds in plasma while also keeping environmentally friendly methods. Accordingly, the aim of this work is to simultaneously determine remdesivir and acetyl salicylic acid through a bioanalytical validated synchronous spectrofluorimetric method with applying principles of green chemistry. Since, the two drugs showed severe overlap after excitation at 242.0 nm, 284.0 nm for remdesivir and acetyl salicylic acid, respectively. The overlap was effectively overcome by using synchronous mode with a wavelength difference (Δλ) of 160.0 nm for remdesivir and 100.0 nm for acetyl salicylic acid. Different parameters have been optimized such as Δλ, solvent, pH and surfactant. A linear calibration was obtained over the concentration range 0.01-4.00 µg/mL for remdesivir and 0.01-3.00 µg/mL for acetyl salicylic acid and the method was precise and accurate. The method was successfully used for the investigation of pharmaceutical formulation and the quantification of the maximum plasma concentration (Cmax) of the two drugs. The method has been evaluated as an excellent green analytical method based on three greenness assessment tools.

Differential Bioactivation Profiles of Different GS-441524 Prodrugs in Cell and Mouse Models: ProTide Prodrugs with High Cell Permeability and Susceptibility to Cathepsin A Are More Efficient in Delivering Antiviral Active Metabolites to the Lung

We assessed factors that determine the tissue-specific bioactivation of ProTide prodrugs by comparing the disposition and activation of remdesivir (RDV), its methylpropyl and isopropyl ester analogues (MeRDV and IsoRDV, respectively), the oral prodrug GS-621763, and the parent nucleotide GS-441524 (Nuc). RDV and MeRDV yielded more active metabolite remdesivir-triphosphate (RDV-TP) than IsoRDV, GS-621763, and Nuc in human lung cell models due to superior cell permeability and higher susceptivity to cathepsin A. Intravenous administration to mice showed that RDV and MeRDV delivered significantly more RDV-TP to the lung than other compounds. Nevertheless, all four ester prodrugs exhibited very low oral bioavailability (<2%), with Nuc being the predominant metabolite in blood. In conclusion, ProTides prodrugs, such as RDV and MeRDV, are more efficient in delivering active metabolites to the lung than Nuc, driven by high cell permeability and susceptivity to cathepsin A. Optimizing ProTides' ester structures is an effective strategy for enhancing prodrug activation in the lung.

Remdesivir Discontinuation Decisions Based on Thresholds of Aminotransferase in an Observational Registry

BACKGROUND

Remdesivir is an antiviral approved by the US Food and Drug Administration (FDA) for treatment of coronavirus disease 2019 (COVID-19), and aminotransferase elevation is commonly reported. Thresholds to be considered for discontinuation due to alanine aminotransferase (ALT) elevation differ between the FDA and European Medicines Agency (EMA). The primary objective was to describe aminotransferase thresholds being used in real-world practice for discontinuation of remdesivir in patients with COVID-19, and compare them with labeled recommendations.

METHODS

This study used a descriptive design based on an ongoing national registry of adverse events, the FDA ACMT COVID-19 ToxIC (FACT) pharmacovigilance project, with 17 participating health systems in the USA. Cases were identified retrospectively for an 18-month period (23 November 2020-18 May 2022). Classification of discontinuation as premature and due to aminotransferases was based on chart documentation by the treating team.

RESULTS

Of 1026 cases in the FACT registry, 116 cases were included with supplemental data forms completed for aminotransferase elevation with remdesivir, defined a priori for inclusion as ALT doubling or increasing by ≥ 50 U/L. ALT was elevated prior to remdesivir in 47% and increased above baseline during dosing by a median of 92 U/L [interquartile range (IQR) 51-164, max 8350]. Remdesivir was discontinued early in 37 (31.9%) patients due to elevated aminotransferases. The ALT threshold for premature discontinuation was median 200 U/L (IQR 145-396, range 92-5743). Among patients with premature discontinuation of remdesivir for aminotransferase elevation, only 21.6% met FDA criteria to consider discontinuation, and 40.5% met prior EMA criteria to consider discontinuation.

CONCLUSION

In this descriptive study of real-world practice in the USA, clinicians are overall making more conservative treatment decisions than are recommended for consideration in approved drug labeling of discontinuation, with wide variation in the aminotransferase thresholds being used.

Risk of acute liver injury following the nirmatrelvir/ritonavir use

BACKGROUND

Elevations in alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were reported as adverse events of nirmatrelvir/ritonavir users in the EPIC-HR trial.

AIM

To quantify the risk and severity of acute liver injury (ALI) associated with nirmatrelvir/ritonavir use.

METHODS

This self-controlled case-series study was conducted using electronic medical records of patients with confirmed diagnosis of SARS-CoV-2 infection between 26th February 2022 and 12th February 2023 in Hong Kong.

RESULTS

Among 2 409 848 patients with SARS-CoV-2 infection during the study period, 153 853 were prescribed with nirmatrelvir/ritonavir, of whom 834 (.5%) had incident ALI (moderate: 30.5%; moderate to severe: 18.9%; severe or fatal: 5.8%). Compared with the non-exposure period, risk of ALI increased significantly during the pre-exposure period (IRR = 38.13, 95% CI = 29.29-49.62) and remained elevated during the five-day nirmatrelvir/ritonavir treatment (IRR = 20.75, 95% CI = 17.06-25.25) and during wash-out period (IRR = 16.27, 95% CI = 13.23-20.01). Compared to the pre-exposure period, risk of ALI was not increased during the five-day nirmatrelvir/ritonavir treatment period (IRR = .54, 95% CI = .43-.70). Compared to 5469 non-nirmatrelvir/ritonavir users with incident ALI, nirmatrelvir/ritonavir users had less severe ALI by the severity index (p < .001) and peak INR (1.7 vs. 2.3; p < .001). ALI cases with nirmatrelvir/ritonavir use had lower risk of all-cause death (29.1% vs. 39.1%; OR = .64; p < .001) and no increase in risk of liver decompensation (1.0% vs. 1.3%; OR = .62; p = .230) compared to non-users.

CONCLUSION

The risk of ALI associated with nirmatrelvir/ritonavir treatment for COVID-19 was elevated in the pre-exposure period, but not following nirmatrelvir/ritonavir initiation. ALI following nirmatrelvir/ritonavir treatment were mostly mild and less severe than ALI events in non-nirmatrelvir/ritonavir users.

Cannabidiol Inhibits In Vitro Human Liver Microsomal Metabolism of Remdesivir

Introduction: The year 2020 began with the world being flounced with a wave of novel coronavirus (severe acute respiratory syndrome coronavirus 2 [SARS-CoV-2]) disease, named COVID-19. Based on promising pre-clinical and clinical data, remdesivir (RDV) was the first drug to receive FDA approval and so far, it is the most common therapy for treatment of SARS-CoV-2/MERS-CoV. However, following intravenous administration, RDV metabolizes majorly by human liver carboxylesterase 1 (CES1) and marginally by the CYP3A4 enzyme in merely less than an hour. Its resultant active metabolite is a hydrophilic nucleoside with very limited accumulation within lung tissues. Therefore, there is a need to investigate strategies to overcome such premature metabolism issues and improve the antiviral efficacy of RDV at the target site. Objective: Considering the major CES1-mediated metabolism of RDV on systemic administration, we intend to explore the remarkable CES1 plus CYP3A4 inhibitory activity of cannabidiol (CBD) against in vitro microsomal metabolism of RDV to indicate its therapeutic potential as an adjuvant to RDV in the treatment and management of COVID-19. Methods: We investigated the in vitro human liver microsomal metabolism of RDV in the presence of two potential CES1 inhibitors-CBD and nelfinavir, and two standard CYP3A4 inhibitors-ritonavir (RITO) and cyclosporin A. The microsomal metabolism assay was further validated by using a well-characterized CYP3A4-selective substrate, midazolam (MDZ), in the presence of CBD and RITO. Results: Our findings depicted that RDV was rapidly and completely metabolized by human liver microsomes within 60 min. Coincubation with CBD substantially reduced microsomal metabolism of RDV and prolonged its in vitro half-life from 8.93 to 31.07 min. CBD showed significantly higher inhibition of RDV compared with known CES1 and CYP3A4 inhibitors. Inhibition of MDZ metabolism by CBD and RITO further validated the assay. Conclusions: The current study strongly suggests that CBD significantly inhibits human liver microsomal metabolism of RDV and extends its in vitro half-life. Thus, concomitant administration of CBD with RDV intravenous injection could be a promising strategy to prevent premature metabolism in COVID-19 patients.

Antiviral attributes of bee venom as a possible therapeutic approach against SARS-CoV-2 infection

The unprecedented scale of the SARS-CoV-2 pandemic has driven considerable investigation into novel antiviral treatments since effective vaccination strategies cannot completely eradicate the virus. Apitherapy describes the medicinal use of bee venom, which may be an effective treatment against SARS-CoV-2 infection. Bee venom contains chemicals that are antimicrobial and stimulate the immune system to counteract viral load. The present review focuses on the use of bee venom as a possible treatment for COVID-19 and reviews studies on the pharmacodynamics of bee venom.

Pulmonary drug delivery: an effective and convenient delivery route to combat COVID-19

The recent outbreak of coronavirus disease 2019 (COVID-19) in Wuhan, China has spread rapidly around the world, leading to a widespread and urgent effort to develop and use comprehensive approaches in the treatment of COVID-19. While oral therapy is accepted as an effective and simple method, since the primary site of infection and disease progression of COVID-19 is mainly through the lungs, inhaled drug delivery directly to the lungs may be the most appropriate route of administration. To prevent or treat primary SARS-CoV-2 infections, it is essential to target the virus port of entry in the respiratory tract and airway epithelium, which requires rapid and high-intensity inhibition or control of viral entry or replication. To achieve success in this field, inhalation therapy is the most attractive treatment approach due to efficacy/safety profiles. In this review article, pulmonary drug delivery as a unique treatment option in lung diseases will be briefly reviewed. Then, possible inhalation therapies for the treatment of symptoms of COVID-19 will be discussed and the results of clinical trials will be presented. By pulmonary delivery of the currently approved drugs for COVID-19, efficacy of the treatment would be improved along with reducing systemic side effects.

How to use COVID-19 antiviral drugs in patients with chronic kidney disease

Antiviral drugs such as Remdesivir (Veklury), Nirmatrelvir with Ritonavir (Paxlovid), Azvudine, and Molnupiravir (Lagevrio) can reduce the risk for severe and fatal Coronavirus Disease (COVID)-19. Although chronic kidney disease is a highly prevalent risk factor for severe and fatal COVID-19, most clinical trials with these drugs excluded patients with impaired kidney function. Advanced CKD is associated with a state of secondary immunodeficiency (SIDKD), which increases the susceptibility to severe COVID-19, COVID-19 complications, and the risk of hospitalization and mortality among COVID-19 patients. The risk to develop COVID-19 related acute kidney injury is higher in patients with precedent CKD. Selecting appropriate therapies for COVID-19 patients with impaired kidney function is a challenge for healthcare professionals. Here, we discuss the pharmacokinetics and pharmacodynamics of COVID-19-related antiviral drugs with a focus on their potential use and dosing in COVID-19 patients with different stages of CKD. Additionally, we describe the adverse effects and precautions to be taken into account when using these antivirals in COVID-19 patients with CKD. Lastly, we also discuss about the use of monoclonal antibodies in COVID-19 patients with kidney disease and related complications.

Remdesivir for the treatment of COVID-19

BACKGROUND

Remdesivir is an antiviral medicine approved for the treatment of mild-to-moderate coronavirus disease 2019 (COVID-19). This led to widespread implementation, although the available evidence remains inconsistent. This update aims to fill current knowledge gaps by identifying, describing, evaluating, and synthesising all evidence from randomised controlled trials (RCTs) on the effects of remdesivir on clinical outcomes in COVID-19.

OBJECTIVES

To assess the effects of remdesivir and standard care compared to standard care plus/minus placebo on clinical outcomes in patients treated for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection.

SEARCH METHODS

We searched the Cochrane COVID-19 Study Register (which comprises the Cochrane Central Register of Controlled Trials (CENTRAL), PubMed, Embase, ClinicalTrials.gov, World Health Organization (WHO) International Clinical Trials Registry Platform, and medRxiv) as well as Web of Science (Science Citation Index Expanded and Emerging Sources Citation Index) and WHO COVID-19 Global literature on coronavirus disease to identify completed and ongoing studies, without language restrictions. We conducted the searches on 31 May 2022.

SELECTION CRITERIA

We followed standard Cochrane methodology. We included RCTs evaluating remdesivir and standard care for the treatment of SARS-CoV-2 infection compared to standard care plus/minus placebo irrespective of disease severity, gender, ethnicity, or setting. We excluded studies that evaluated remdesivir for the treatment of other coronavirus diseases.

DATA COLLECTION AND ANALYSIS

We followed standard Cochrane methodology. To assess risk of bias in included studies, we used the Cochrane RoB 2 tool for RCTs. We rated the certainty of evidence using the GRADE (Grading of Recommendations, Assessment, Development and Evaluation) approach for outcomes that were reported according to our prioritised categories: all-cause mortality, in-hospital mortality, clinical improvement (being alive and ready for discharge up to day 28) or worsening (new need for invasive mechanical ventilation or death up to day 28), quality of life, serious adverse events, and adverse events (any grade). We differentiated between non-hospitalised individuals with asymptomatic SARS-CoV-2 infection or mild COVID-19 and hospitalised individuals with moderate to severe COVID-19.

MAIN RESULTS

We included nine RCTs with 11,218 participants diagnosed with SARS-CoV-2 infection and a mean age of 53.6 years, of whom 5982 participants were randomised to receive remdesivir. Most participants required low-flow oxygen at baseline. Studies were mainly conducted in high- and upper-middle-income countries. We identified two studies that are awaiting classification and five ongoing studies. Effects of remdesivir in hospitalised individuals with moderate to severe COVID-19 With moderate-certainty evidence, remdesivir probably makes little or no difference to all-cause mortality at up to day 28 (risk ratio (RR) 0.93, 95% confidence interval (CI) 0.81 to 1.06; risk difference (RD) 8 fewer per 1000, 95% CI 21 fewer to 6 more; 4 studies, 7142 participants), day 60 (RR 0.85, 95% CI 0.69 to 1.05; RD 35 fewer per 1000, 95% CI 73 fewer to 12 more; 1 study, 1281 participants), or in-hospital mortality at up to day 150 (RR 0.93, 95% CI 0.84 to 1.03; RD 11 fewer per 1000, 95% CI 25 fewer to 5 more; 1 study, 8275 participants). Remdesivir probably increases the chance of clinical improvement at up to day 28 slightly (RR 1.11, 95% CI 1.06 to 1.17; RD 68 more per 1000, 95% CI 37 more to 105 more; 4 studies, 2514 participants; moderate-certainty evidence). It probably decreases the risk of clinical worsening within 28 days (hazard ratio (HR) 0.67, 95% CI 0.54 to 0.82; RD 135 fewer per 1000, 95% CI 198 fewer to 69 fewer; 2 studies, 1734 participants, moderate-certainty evidence). Remdesivir may make little or no difference to the rate of adverse events of any grade (RR 1.04, 95% CI 0.92 to 1.18; RD 23 more per 1000, 95% CI 46 fewer to 104 more; 4 studies, 2498 participants; low-certainty evidence), or serious adverse events (RR 0.84, 95% CI 0.65 to 1.07; RD 44 fewer per 1000, 95% CI 96 fewer to 19 more; 4 studies, 2498 participants; low-certainty evidence). We considered risk of bias to be low, with some concerns for mortality and clinical course. We had some concerns for safety outcomes because participants who had died did not contribute information. Without adjustment, this leads to an uncertain amount of missing values and the potential for bias due to missing data. Effects of remdesivir in non-hospitalised individuals with mild COVID-19 One of the nine RCTs was conducted in the outpatient setting and included symptomatic people with a risk of progression. No deaths occurred within the 28 days observation period. We are uncertain about clinical improvement due to very low-certainty evidence. Remdesivir probably decreases the risk of clinical worsening (hospitalisation) at up to day 28 (RR 0.28, 95% CI 0.11 to 0.75; RD 46 fewer per 1000, 95% CI 57 fewer to 16 fewer; 562 participants; moderate-certainty evidence). We did not find any data for quality of life. Remdesivir may decrease the rate of serious adverse events at up to 28 days (RR 0.27, 95% CI 0.10 to 0.70; RD 49 fewer per 1000, 95% CI 60 fewer to 20 fewer; 562 participants; low-certainty evidence), but it probably makes little or no difference to the risk of adverse events of any grade (RR 0.91, 95% CI 0.76 to 1.10; RD 42 fewer per 1000, 95% CI 111 fewer to 46 more; 562 participants; moderate-certainty evidence). We considered risk of bias to be low for mortality, clinical improvement, and safety outcomes. We identified a high risk of bias for clinical worsening.

AUTHORS' CONCLUSIONS

Based on the available evidence up to 31 May 2022, remdesivir probably has little or no effect on all-cause mortality or in-hospital mortality of individuals with moderate to severe COVID-19. The hospitalisation rate was reduced with remdesivir in one study including participants with mild to moderate COVID-19. It may be beneficial in the clinical course for both hospitalised and non-hospitalised patients, but certainty remains limited. The applicability of the evidence to current practice may be limited by the recruitment of participants from mostly unvaccinated populations exposed to early variants of the SARS-CoV-2 virus at the time the studies were undertaken.  Future studies should provide additional data on the efficacy and safety of remdesivir for defined core outcomes in COVID-19 research, especially for different population subgroups.

Multi-Targeting Approach in Selection of Potential Molecule for COVID-19 Treatment

The coronavirus disease (COVID-19) is a pandemic that started in the City of Wuhan, Hubei Province, China, caused by the spread of coronavirus (SARS-CoV-2). Drug discovery teams around the globe are in a race to develop a medicine for its management. It takes time for a novel molecule to enter the market, and the ideal way is to exploit the already approved drugs and repurpose them therapeutically. We have attempted to screen selected molecules with an affinity towards multiple protein targets in COVID-19 using the Schrödinger suit for in silico predictions. The proteins selected were angiotensin-converting enzyme-2 (ACE2), main protease (MPro), and spike protein. The molecular docking, prime MM-GBSA, induced-fit docking (IFD), and molecular dynamics (MD) simulations were used to identify the most suitable molecule that forms a stable interaction with the selected viral proteins. The ligand-binding stability for the proteins PDB-IDs 1ZV8 (spike protein), 5R82 (Mpro), and 6M1D (ACE2), was in the order of nintedanib > quercetin, nintedanib > darunavir, nintedanib > baricitinib, respectively. The MM-GBSA, IFD, and MD simulation studies imply that the drug nintedanib has the highest binding stability among the shortlisted. Nintedanib, primarily used for idiopathic pulmonary fibrosis, can be considered for repurposing for us against COVID-19.

A hypothesis on designing strategy of effective RdRp inhibitors for the treatment of SARS-CoV-2

Vaccines are used as one of the major weapons for the eradication of pandemic. However, the rise of different variants of the SARS-CoV-2 virus is creating doubts regarding the end of the pandemic. Hence, there is an urgent need to develop more drug candidates which can be useful for the treatment of COVID-19. In the present research for the scientific hypothesis, emphasis was given on the direct antiviral therapy available for the treatment of COVID-19. In lieu of this, the available molecular targets which include Severe Acute Respiratory Syndrome Chymotrypsin-like Protease (SARS-3CLpro), Papain-Like Cysteine Protease (PLpro), and RNA-Dependent RNA Polymerase (RdRp) were explored. As per the current scientific reports and literature, among all the available molecular targets, RNA-Dependent RNA Polymerase (RdRp) was found to be a crucial molecular target for the treatment of COVID-19. Most of the inhibitors which are reported against this target consisted of the free amine group and carbonyl group which might be playing an important role in the binding interaction with the RdRp protein. Among all the reported RdRp inhibitors, remdesivir, favipiravir, and molnupiravir were found to be the most promising drugs against COVID-19. Overall, the structural features of this RNA-Dependent RNA Polymerase (RdRp) inhibitors proved the importance of pyrrolo-triazine and pyrimidine scaffolds. Previous computational models of these drug molecules indicated that substitution with the polar functional group, hydrogen bond donor, and electronegative atoms on these scaffolds may increase the activity against the RdRp protein. Hence, in line with the proposed hypothesis, in the present research work for the evaluation of the hypothesis, new molecules were designed from the pyrrolo-triazine and pyrimidine scaffolds. Further, molecular docking and MD simulation studies were performed with these designed molecules. All these designed molecules (DM-1, DM-2, and DM-3) showed the results as per the proposed hypothesis. Among all the designed molecules, DM-1 showed promising results against the RdRp protein of SARS-CoV-2. In the future, these structural features can be used for the development of new RdRp inhibitors with improved activity. Also, in the future lead compound DM-1 can be explored against the RdRp protein for the treatment of COVID-19.

Endurance of COVID 19 in wastewater, natural prescription and antiviral medication for the analysis of COVID 19 and its effects on the development of new antiseptic strategies

The continuous worldwide pandemic of COVID-19 brought about by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has been a public health emergency of international concern, which was formally announced by the World Health Organization (WHO). The antivirals utilized to restrict the spread of virus and the procedures for the recognition of SARS-COV-2 in wastewater has been reviewed. A main tool Wastewater-based epidemiology (WBE) played a notable role in tracking the spread of corona virus in large community. This review signifies the upgraded clinical impacts and components of Traditional Chinese Medicine (TCM), the function of various antiviral drugs against COVID 19 and the role of human covid to exist in the habitat and the viability countered; with specific spotlight on the advancement of latest strategies to assess the action of latest antiseptic-disinfectants on infections.

Tissue- and cell-expression of druggable host proteins provide insights into repurposing drugs for COVID-19

Several human host proteins play important roles in the lifecycle of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Many drugs targeting these host proteins have been investigated as potential therapeutics for coronavirus disease 2019 (COVID-19). The tissue-specific expressions of selected host proteins were summarized using proteomics data retrieved from the Human Protein Atlas, ProteomicsDB, Human Proteome Map databases, and a clinical COVID-19 study. Protein expression features in different cell lines were summarized based on recent proteomics studies. The half-maximal effective concentration or half-maximal inhibitory concentration values were collected from in vitro studies. The pharmacokinetic data were mainly from studies in healthy subjects or non-COVID-19 patients. Considerable tissue-specific expression patterns were observed for several host proteins. ACE2 expression in the lungs was significantly lower than in many other tissues (e.g., the kidneys and intestines); TMPRSS2 expression in the lungs was significantly lower than in other tissues (e.g., the prostate and intestines). The expression levels of endocytosis-associated proteins CTSL, CLTC, NPC1, and PIKfyve in the lungs were comparable to or higher than most other tissues. TMPRSS2 expression was markedly different between cell lines, which could be associated with the cell-dependent antiviral activities of several drugs. Drug delivery receptor ICAM1 and CTSB were expressed at a higher level in the lungs than in other tissues. In conclusion, the cell- and tissue-specific proteomics data could help interpret the in vitro antiviral activities of host-directed drugs in various cells and aid the transition of the in vitro findings to clinical research to develop safe and effective therapeutics for COVID-19.

An Overview of Repurposed Drugs for Potential COVID-19 Treatment

The COVID-19 pandemic caused by SARS-CoV-2 has placed severe constraints on healthcare systems around the globe. The SARS-CoV-2 virus has caused upheaval in the healthcare and economic sectors worldwide. On the 20th of May 2020, the World Health Organisation declared COVID-19 a global pandemic due to the unprecedented number of cases reported around the globe. As of the 4th of November 2022, there were 637,117,429 coronavirus cases reported globally by Worldometer stats, with 6,602,572 related deaths. In South Africa, there were approximately 4,029,496 coronavirus cases and 102,311 associated deaths. As such, there is a need for efficacious therapeutic regimes. There has been a paucity of knowledge encompassing the use of effective and specific antiviral drug therapies for treating COVID-19 since the outbreak. In this review, we provide valuable insights into the repurposing of current drugs for COVID-19. Drug repurposing provides a suitable option for the discovery of efficacious drugs for COVID-19, thereby decreasing the costs and turnaround times of drug development strategies. This review provides an overview of ten drugs, including antimalarial, antiparasitic, anti-inflammatory, nucleoside analogue, monoclonal-antibody drugs, that were repurposed for the potential treatment of COVID-19.

Synergistic drug combinations designed to fully suppress SARS-CoV-2 in the lung of COVID-19 patients

Despite new antivirals are being approved against SARS-CoV-2 they suffer from significant constraints and are not indicated for hospitalized patients, who are left with few antiviral options. Repurposed drugs have previously shown controversial clinical results and it remains difficult to understand why certain trials delivered positive results and other trials failed. Our manuscript contributes to explaining the puzzle: this might have been caused by a suboptimal drug exposure and, consequently, an incomplete virus suppression, also because the drugs have mostly been used as add-on monotherapies. As with other viruses (e.g., HIV and HCV) identifying synergistic combinations among such drugs could overcome monotherapy-related limitations. In a cell culture model for SARS-CoV-2 infection the following stringent criteria were adopted to assess drug combinations: 1) identify robust, synergistic antiviral activity with no increase in cytotoxicity, 2) identify the lowest drug concentration inhibiting the virus by 100% (LIC100) and 3) understand whether the LIC100 could be reached in the lung at clinically indicated drug doses. Among several combinations tested, remdesivir with either azithromycin or ivermectin synergistically increased the antiviral activity with no increase in cytotoxicity, improving the therapeutic index and lowering the LIC100 of every one of the drugs to levels that are expected to be achievable and maintained in the lung for a therapeutically relevant period of time. These results are consistent with recent clinical observations showing that intensive care unit admission was significantly delayed by the combination of AZI and RDV, but not by RDV alone, and could have immediate implications for the treatment of hospitalized patients with COVID-19 as the proposed "drug cocktails" should have antiviral activity against present and future SARS-CoV-2 variants without significant overlapping toxicity, while minimizing the onset of drug resistance. Our results also provide a validated methodology to help sort out which combination of drugs are most likely to be efficacious in vivo, based on their in vitro activity, potential synergy and PK profiles.

Pulmonary Delivery of Favipiravir in Rats Reaches High Local Concentrations without Causing Oxidative Lung Injury or Systemic Side Effects

Favipiravir displays a rapid viral clearance, a high recovery rate and broad therapeutic safety; however, its oral administration was associated with systemic side effects in susceptible patients. Considering that the pulmonary route could provide a high drug concentration, and a safer application with less absorption into systemic circulation, it was aimed to elucidate whether favipiravir delivered via soft-mist inhaler has any deleterious effects on lung, liver and kidney tissues of healthy rats. Wistar albino rats of both sexes (n = 72) were placed in restrainers, and were given either saline or favipiravir (1, 2.5, 5 or 10 mg/kg in 1 mL saline) by inhalation within 2 min for 5 consecutive days. On the 6th day, electrocardiographic recording was obtained, and cardiac blood and lung tissues were collected. Favipiravir did not alter cardiac rhythm, blood cell counts, serum levels of alanine transaminase, aspartate transaminase, blood urea nitrogen, creatinine, urea or uric acid, and did not cause any significant changes in the pulmonary malondialdehyde, myeloperoxidase activity or antioxidant glutathione levels. Our data revealed that pulmonary use of favipiravir via soft-mist inhaler enables a high local concentration compared to plasma without oxidative lung injury or cardiac or hepatorenal dysfunction.

Discovery of SARS-CoV-2 antiviral synergy between remdesivir and approved drugs in human lung cells

SARS coronavirus 2 (SARS-CoV-2) has caused an ongoing global pandemic with significant mortality and morbidity. At this time, the only FDA-approved therapeutic for COVID-19 is remdesivir, a broad-spectrum antiviral nucleoside analog. Efficacy is only moderate, and improved treatment strategies are urgently needed. To accomplish this goal, we devised a strategy to identify compounds that act synergistically with remdesivir in preventing SARS-CoV-2 replication. We conducted combinatorial high-throughput screening in the presence of submaximal remdesivir concentrations, using a human lung epithelial cell line infected with a clinical isolate of SARS-CoV-2. This identified 20 approved drugs that act synergistically with remdesivir, many with favorable pharmacokinetic and safety profiles. Strongest effects were observed with established antivirals, Hepatitis C virus nonstructural protein 5A (HCV NS5A) inhibitors velpatasvir and elbasvir. Combination with their partner drugs sofosbuvir and grazoprevir further increased efficacy, increasing remdesivir's apparent potency > 25-fold. We report that HCV NS5A inhibitors act on the SARS-CoV-2 exonuclease proofreader, providing a possible explanation for the synergy observed with nucleoside analog remdesivir. FDA-approved Hepatitis C therapeutics Epclusa® (velpatasvir/sofosbuvir) and Zepatier® (elbasvir/grazoprevir) could be further optimized to achieve potency and pharmacokinetic properties that support clinical evaluation in combination with remdesivir.

Antivirals and the Potential Benefits of Orally Inhaled Drug Administration in COVID-19 Treatment

Coronavirus Disease 2019 (COVID-19) pandemic has been on the agenda of humanity for more than 2 years. In the meantime, the pandemic has caused economic shutdowns, halt of daily lives and global mobility, overcrowding of the healthcare systems, panic, and worse, more than 6 million deaths. Today, there is still no specific therapy for COVID-19. Research focuses on repurposing of antiviral drugs that are licensed or currently in the research phase, with a known systemic safety profile. However, local safety profile should also be evaluated depending on the new indication, administration route and dosage form. Additionally, various vaccines have been developed. But the causative virus, Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2), has undergone multiple variations, too. The premise that vaccines may suffice to eradicate new and all variants is unreliable, as they are based on earlier versions of the virus. Therefore, a specific medication therapy for COVID-19 is crucial and needed in order to prevent severe complications of the disease. Even though there is no specific drug that inhibits the replication of the disease-causing virus, among the current treatment options, systemic antivirals are the most medically appropriate. As SARS-CoV-2 directly targets the lungs and initiates lung damage, treating COVID-19 with inhalants can offer many advantages over the enteral/parenteral administration. Inhaled drug delivery provides higher drug concentration, specifically in the pulmonary system. This enables the reduction of systemic side effects and produces a rapid clinical response. In this article, the most frequently (systemically) used antiviral compounds are reviewed including Remdesivir, Favipiravir, Molnupiravir, Lopinavir-Ritonavir, Umifenovir, Chloroquine, Hydroxychloroquine and Heparin. A comprehensive literature search was conducted to provide insight into the potential inhaled use of these antiviral drugs and the current studies on inhalation therapy for COVID-19 was presented. A brief evaluation was also made on the use of inhaler devices in the treatment of COVID-19. Inhaled antivirals paired with suitable inhaler devices should be considered for COVID-19 treatment options.

A randomized, open-label trial of combined nitazoxanide and atazanavir/ritonavir for mild to moderate COVID-19

Background

The nitazoxanide plus atazanavir/ritonavir for COVID-19 (NACOVID) trial investigated the efficacy and safety of repurposed nitazoxanide combined with atazanavir/ritonavir for COVID-19.

Methods

This is a pilot, randomized, open-label multicenter trial conducted in Nigeria. Mild to moderate COVID-19 patients were randomly assigned to receive standard of care (SoC) or SoC plus a 14-day course of nitazoxanide (1,000 mg b.i.d.) and atazanavir/ritonavir (300/100 mg od) and followed through day 28. Study endpoints included time to clinical improvement, SARS-CoV-2 viral load change, and time to complete symptom resolution. Safety and pharmacokinetics were also evaluated (ClinicalTrials.gov ID: NCT04459286).

Results

There was no difference in time to clinical improvement between the SoC (n = 26) and SoC plus intervention arms (n = 31; Cox proportional hazards regression analysis adjusted hazard ratio, aHR = 0.898, 95% CI: 0.492-1.638, p = 0.725). No difference was observed in the pattern of saliva SARS-CoV-2 viral load changes from days 2-28 in the 35% of patients with detectable virus at baseline (20/57) (aHR = 0.948, 95% CI: 0.341-2.636, p = 0.919). There was no significant difference in time to complete symptom resolution (aHR = 0.535, 95% CI: 0.251-1.140, p = 0.105). Atazanavir/ritonavir increased tizoxanide plasma exposure by 68% and median trough plasma concentration was 1,546 ng/ml (95% CI: 797-2,557), above its putative EC90 in 54% of patients. Tizoxanide was undetectable in saliva.

Conclusion

Nitazoxanide co-administered with atazanavir/ritonavir was safe but not better than standard of care in treating COVID-19. These findings should be interpreted in the context of incomplete enrollment (64%) and the limited number of patients with detectable SARS-CoV-2 in saliva at baseline in this trial.

Clinical trial registration

[https://clinicaltrials.gov/ct2/show/NCT04459286], identifier [NCT04459286].

Comprehensive role of SARS-CoV-2 spike glycoprotein in regulating host signaling pathway

Since the outbreak of coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, global public health and the economy have suffered unprecedented damage. Based on the increasing related literature, the characteristics and pathogenic mechanisms of the virus, and epidemiological and clinical features of the disease are being rapidly discovered. The spike glycoprotein (S protein), as a key antigen of SARS-CoV-2 for developing vaccines, antibodies, and drug targets, has been shown to play an important role in viral entry, tissue tropism, and pathogenesis. In this review, we summarize the molecular mechanisms of interaction between S protein and host factors, especially receptor-mediated viral modulation of host signaling pathways, and highlight the progression of potential therapeutic targets, prophylactic and therapeutic agents for prevention and treatment of SARS-CoV-2 infection.

Remdesivir-loaded bis-MPA hyperbranched dendritic nanocarriers for pulmonary delivery

Remdesivir is the only clinically available antiviral drug for the treatment of COVID-19. However, its very limited aqueous solubility confines its therapeutic activity and the development of novel inhaled nano-based drug delivery systems of remdesivir for enhanced lung tissue targeting and efficacy is internationally pursued. In this work 2,2-bis(hydroxymethyl)propionic acid (bis-MPA) hyperbranched dendritic nano-scaffolds were employed as nanocarriers of remdesivir. The produced nano-formulations, empty and loaded, consisted of monodisperse nanoparticles with spherical morphology and neutral surface charge and sizes ranging between 80 and 230 nm. The entrapment efficiency and loading capacity of the loaded samples were 82.0% and 14.1%, respectively, whereas the release of the encapsulated drug was complete after 48 h. The toxicity assays in healthy MRC-5 lung diploid fibroblasts and NR8383 alveolar macrophages indicated their suitability as potential remdesivir carriers in the respiratory system. The novel nano-formulations are non-toxic in both tested cell lines, with IC₅₀ values higher than 400 μΜ after 72 h treatment. Moreover, both free and encapsulated remdesivir exhibited very similar IC₅₀ values, at the range of 80-90 μM, while its aqueous solubility was increased, overall presenting a suitable profile for application in inhaled delivery of therapeutics.

Inhaled therapy for COVID-19: Considerations of drugs, formulations and devices

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the etiological agent responsible for the COVID-19 pandemic, has outspread at full tilt across the world. Although several effective vaccines continue to be deployed, reliable antiviral treatments have yet to be developed against this disease. Currently, available therapeutics for COVID-19 include repurposed, and a few novel drugs. Many drugs have been promising in preclinical studies, but a majority of these drugs have shown little or no efficacy in clinical studies. One of the major reasons is the insufficient drug concentration in the lung, the primary target site of infection for SARS-CoV-2, from the administration of drugs through oral or intravenous routes. Higher effective doses administered through these routes could also lead to adverse side effects. For this reason, inhaled treatments are being tested as an efficient approach for COVID-19, allowing lower doses of drugs ensuring higher concentrations of the drug(s) in the lung. The inhaled treatment combining two or more antiviral drugs will increase potency and reduce the possibility of selecting for SARS-CoV-2 variants with reduced drug susceptibility. Finally, the appropriate drug combination needs to be delivered using a suitable system. Here, we review the current treatment for COVID-19 and their limitations, discussing the advantages of mono and combinational inhaled therapy with a brief outline of the recently reformulated anti-SARS-CoV-2 agents as inhaled formulations. The selection of appropriate delivery devices for inhalation and associated key considerations including the formulation challenges are also discussed.

Remdesivir Powders Manufactured by Jet Milling for Potential Pulmonary Treatment of COVID-19

Remdesivir is one of the effective drugs proposed for the treatment of coronavirus disease 2019 (COVID-19). However, the study on inhalable regimen is currently limited though COVID-19 is respiratory diseases and infects lung area. This work aims to prepare inhalable remdesivir formulations and verify their effectiveness through in vitro evaluations.Formulations containing different ratios of jet-milled inhalable remdesivir (5%, 10%, 20%,40%,70%) with excipients were produced and characterized in terms of the particle size distribution, particle morphology, flowability, water content, crystallinity, the water sorption and desorption capabilities and the aerodynamic performance.Results indicating that drug loading is a vital factor in facilitating the dispersion of remdesivir dry powder, and the ternary excipient plays a negligible role in improving aerosol performance. Besides, the 70% remdesivir with lactose carrier (70%RD-Lac) was physically stable and retain high aerosol performance after conditioned at 40 °C and 75% RH for a month. Therefore, formulation 70% RD-Lac might be recommended as a candidate product for the potential treatment of COVID-19.

Biotransformation and transplacental transfer of the anti-viral remdesivir and predominant metabolite, GS-441524 in pregnant rats

BACKGROUND

Remdesivir was the first prodrug approved to treat coronavirus disease 2019 (COVID-19) and has the potential to be used during pregnancy. However, it is not known whether remdesivir and its main metabolite, GS-441524 have the potential to cross the blood-placental barrier. We hypothesize that remdesivir and predominant metabolite GS-441524may cross the blood-placental barrier to reach the embryo tissues.

METHODS

To test this hypothesis, ultra-high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) coupled with multisite microdialysis was used to monitor the levels of remdesivir and the nucleoside analogue GS-441524 in the maternal blood, fetus, placenta, and amniotic fluid of pregnant Sprague-Dawley rats. The transplacental transfer was evaluated using the pharmacokinetic parameters of AUC and mother-to-fetus transfer ratio (AUCfetus/AUCmother).

FINDINGS

Our in-vivo results show that remdesivir is rapidly biotransformed into GS-441524 in the maternal blood, which then readily crossed the placenta with a mother-to-fetus transfer ratio of 0.51 ± 0.18. The Cmax and AUClast values of GS-441524 followed the order: maternal blood > amniotic fluid > fetus > placenta in rats.

INTERPRETATION

While remdesivir does not directly cross into the fetus, however, its main metabolite, GS-441524 readily crosses the placenta and can reside there for at least 4 hours as shown in the pregnant Sprague-Dawley rat model. These findings suggest that careful consideration should be taken for the use of remdesivir in the treatment of COVID-19 in pregnancy.

FUNDING

Ministry of Science and Technology of Taiwan.

Animal models for studying coronavirus infections and developing antiviral agents and vaccines

In addition to severe acute respiratory syndrome coronavirus (SARS-CoV) and Middle East respiratory syndrome coronavirus (MERS-CoV), SARS-CoV-2 has become the third deadly coronavirus that infects humans and causes the new coronavirus disease (COVID-19). COVID-19 has already caused more than six million deaths worldwide and it is likely the biggest pandemic of this century faced by mankind. Although many studies on SARS-CoV-2 have been conducted, a detailed understanding of SARS-CoV-2 and COVID-19 is still lacking. Animal models are indispensable for studying its pathogenesis and developing vaccines and antivirals. In this review, we analyze animal models of coronavirus infections and explore their applications on antivirals and vaccines.

Why 90% of clinical drug development fails and how to improve it?

Ninety percent of clinical drug development fails despite implementation of many successful strategies, which raised the question whether certain aspects in target validation and drug optimization are overlooked? Current drug optimization overly emphasizes potency/specificity using structure‒activity-relationship (SAR) but overlooks tissue exposure/selectivity in disease/normal tissues using structure‒tissue exposure/selectivity-relationship (STR), which may mislead the drug candidate selection and impact the balance of clinical dose/efficacy/toxicity. We propose structure‒tissue exposure/selectivity-activity relationship (STAR) to improve drug optimization, which classifies drug candidates based on drug's potency/selectivity, tissue exposure/selectivity, and required dose for balancing clinical efficacy/toxicity. Class I drugs have high specificity/potency and high tissue exposure/selectivity, which needs low dose to achieve superior clinical efficacy/safety with high success rate. Class II drugs have high specificity/potency and low tissue exposure/selectivity, which requires high dose to achieve clinical efficacy with high toxicity and needs to be cautiously evaluated. Class III drugs have relatively low (adequate) specificity/potency but high tissue exposure/selectivity, which requires low dose to achieve clinical efficacy with manageable toxicity but are often overlooked. Class IV drugs have low specificity/potency and low tissue exposure/selectivity, which achieves inadequate efficacy/safety, and should be terminated early. STAR may improve drug optimization and clinical studies for the success of clinical drug development.

Exploring antiviral and anti-inflammatory effects of thiol drugs in COVID-19

The redox status of the cysteine-rich SARS-CoV-2 spike glycoprotein (SARS-2-S) is important for the binding of SARS-2-S to angiotensin-converting enzyme 2 (ACE2), suggesting that drugs with a functional thiol group (“thiol drugs”) may cleave cystines to disrupt SARS-CoV-2 cell entry. In addition, neutrophil-induced oxidative stress is a mechanism of COVID-19 lung injury, and the antioxidant and anti-inflammatory properties of thiol drugs, especially cysteamine, may limit this injury. To first explore the antiviral effects of thiol drugs in COVID-19, we used an ACE-2 binding assay and cell entry assays utilizing reporter pseudoviruses and authentic SARS-CoV-2 viruses. We found that multiple thiol drugs inhibit SARS-2-S binding to ACE2 and virus infection. The most potent drugs were effective in the low millimolar range, and IC₅₀ values followed the order of their cystine cleavage rates and lower thiol pK_a values. To determine if thiol drugs have antiviral effects in vivo and to explore any anti-inflammatory effects of thiol drugs in COVID-19, we tested the effects of cysteamine delivered intraperitoneally to hamsters infected with SARS-CoV-2. Cysteamine did not decrease lung viral infection, but it significantly decreased lung neutrophilic inflammation and alveolar hemorrhage. We speculate that the concentration of cysteamine achieved in the lungs with intraperitoneal delivery was insufficient for antiviral effects but sufficient for anti-inflammatory effects. We conclude that thiol drugs decrease SARS-CoV-2 lung inflammation and injury, and we provide rationale for future studies to test if direct (aerosol) delivery of thiol drugs to the airways might also result in antiviral effects.

Remdesivir: an overview of patenting trends, clinical evidence on COVID-19 treatment, pharmacology and chemistry

By December 2021, the COVID-19 caused approximately 6.1 million deaths around the world. Several vaccines have been approved, but there is still a need for non-prophylactic treatments for COVID-19. Remdesivir is an antiviral drug approved for emergency use against COVID-19 in several countries, but one of the first clinical trials was inconclusive about the mortality reduction, although the drug showed a reduction in the recovery time of hospitalized patients. Thus, the present investigation revisits the clinical evidence of using remdesivir for COVID-19 treatment, patent status, pharmacology and chemistry. We found 184 families of patents in the Cortellis database, and concerning the clinical evidence, we retrieved 14 systematic reviews with meta-analysis involving remdesivir as a treatment for COVID-19, discussing the reduction of adverse events, hospitalization days, mortality rate and the mechanical ventilation period.

Modeling explains prolonged SARS-CoV-2 nasal shedding relative to lung shedding in remdesivir treated rhesus macaques

In clinical trials, remdesivir decreased recovery time in hospitalized patients with SARS- CoV-2 and prevented hospitalization when given early during infection, despite not reducing nasal viral loads. In rhesus macaques, early remdesivir prevented pneumonia and lowered lung viral loads, but viral loads increased in nasal passages after five days. We developed mathematical models to explain these results. Our model raises the hypotheses that: 1) in contrast to nasal passages viral load monotonically decreases in lungs during therapy because of infection-dependent generation of refractory cells, 2) slight reduction in lung viral loads with an imperfect agent may result in a substantial decrease in lung damage, and 3) increases in nasal viral load may occur due to a blunting of peak viral load which decreases the intensity of the innate immune response. We demonstrate that a higher potency drug could lower viral loads in nasal passages and lung.

Remdesivir and Its Combination With Repurposed Drugs as COVID-19 Therapeutics

The SARS-CoV-2 virus needs multiple copies for its multiplication using an enzyme RNA-dependent RNA polymerase (RdRp). Remdesivir inhibits viral RdRp, controls the multiplication of the virus, and protects patients. However, treatment of COVID-19 with remdesivir involves adverse effects. Many ongoing clinical trials are exploring the potential of the combination of remdesivir with repurposed drugs by targeting multiple targets of virus and host human simultaneously. Better results were obtained with the remdesivir–baricitinib combination treatment for COVID-19 compared to the treatment with remdesivir alone. Notably, recovery from COVID-19 was found to be 8 days less via the remdesivir–baricitinib combination treatment as compared to remdesivir treatment alone. Furthermore, the mortality rate via the remdesivir–baricitinib combination treatment was lower compared to the remdesivir-only treatment. Remdesivir targets the SARS-CoV-2 enzyme while baricitinib targets the host human enzyme. Simultaneously, remdesivir and baricitinib as a combination inhibit their target viral RdRp and human Janus kinase, respectively. Ongoing trials for the combination of drugs will suggest in the future whether they may reduce the recovery time, reduce the mortality rate, and improve patient clinical status for noninvasive ventilation. In the future, simultaneously targeting virus replication enzymes and host human kinases may be the strategy for SARS-CoV-2 therapeutics.

Multiscale Model of Antiviral Timing, Potency, and Heterogeneity Effects on an Epithelial Tissue Patch Infected by SARS-CoV-2

We extend our established agent-based multiscale computational model of infection of lung tissue by SARS-CoV-2 to include pharmacokinetic and pharmacodynamic models of remdesivir. We model remdesivir treatment for COVID-19; however, our methods are general to other viral infections and antiviral therapies. We investigate the effects of drug potency, drug dosing frequency, treatment initiation delay, antiviral half-life, and variability in cellular uptake and metabolism of remdesivir and its active metabolite on treatment outcomes in a simulated patch of infected epithelial tissue. Non-spatial deterministic population models which treat all cells of a given class as identical can clarify how treatment dosage and timing influence treatment efficacy. However, they do not reveal how cell-to-cell variability affects treatment outcomes. Our simulations suggest that for a given treatment regime, including cell-to-cell variation in drug uptake, permeability and metabolism increase the likelihood of uncontrolled infection as the cells with the lowest internal levels of antiviral act as super-spreaders within the tissue. The model predicts substantial variability in infection outcomes between similar tissue patches for different treatment options. In models with cellular metabolic variability, antiviral doses have to be increased significantly (>50% depending on simulation parameters) to achieve the same treatment results as with the homogeneous cellular metabolism.

Development of targeted nanoparticles loaded with antiviral drugs for SARS-CoV-2 inhibition

Recently, a novel coronavirus, known as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has raised global concerns, being the etiological agent of the current pandemic infectious coronavirus disease 2019 (COVID-19). Specific prophylactic treatments like vaccines, have been authorized for use by regulatory bodies in multiple countries, however there is an urgent need to identify new, safe, and targeted therapeutics as post-exposure therapy for COVID-19. Among a plethora of potential pharmacological targets, the angiotensin-converting enzyme 2 (ACE2) membrane receptor, which plays a crucial role in viral entry, is representing an attractive intervention opportunity for SARS-CoV-2 antiviral discovery process. In this scenario, we envisioned that binding to ACE2 by multivalent attachment of ligands to nanocarriers incorporating antiviral therapeutics, it would increase receptor avidity and impart specificity to these nanovectors for host cells, particularly in the pulmonary tract, which is the primary entry route for SARS-CoV-2. Herein, we report the design and development of novel polymeric nanoparticles (NP), densely grafted with various ligands to selectively bind to ACE2, as innovative nanovectors for targeted drug delivery. We first evaluated the impact of these biocompatible targeted NP (TNP) on ligand binding toward ACE2 and measured their competition ability vs a model of spike protein (Lipo-S1). Next, we tested the effectiveness of the most performing nanoprotopype, TNP-1, loaded with a model anti-SARS-CoV-2 drug such as remdesivir (RDV), on antiviral activity against SARS-CoV-2 infected Vero E6 cells. The RDV-TNP-1 exhibited a significantly improved antiviral effect compared to RDV at the same concentration. Interestingly, unloaded TNP (TNP-1E) also exhibited a basal antiviral activity, potentially due to a direct competitive mechanism with viral particles for the ACE2 binding site. We also measured the anti-exopeptidase activity of TNP-1E against ACE2 protein. Collectively, these insights warrant in-depth preclinical development for our nanoprototypes, for example as potential inhalable drug carriers, with the perspective of a clinical translation.

Therapeutic dilemmas in addressing SARS-CoV-2 infection: Favipiravir versus Remdesivir

Coronavirus disease 2019 (COVID-19) represents an unmet clinical need, due to a high mortality rate, rapid mutation rate in the virus, increased chances of reinfection, lack of effectiveness of repurposed drugs and economic damage. COVID-19 pandemic has created an urgent need for effective molecules. Clinically proven efficacy and safety profiles have made favipiravir (FVP) and remdesivir (RDV) promising therapeutic options for use against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Even though both are prodrug molecules with an antiviral role based on a similar mechanism of action, differences in pharmacological, pharmacokinetic and pharmacotoxicological mechanisms have been identified. The present study aims to provide a comprehensive comparative assessment of FVP and RDV against SARS-CoV-2 infections, by centralizing medical data provided by significant literature and authorized clinical trials, focusing on the importance of a better understanding of the interactions between drug molecules and infectious agents in order to improve the global management of COVID-19 patients and to reduce the risk of antiviral resistance.

Identification of novel SARS-CoV-2 RNA dependent RNA polymerase (RdRp) inhibitors: From in silico screening to experimentally validated inhibitory activity

The emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in 2019 has posed a serious threat to global health and the economy for over two years, prompting the need for development of antiviral inhibitors. Due to its vital role in viral replication, RNA-dependent RNA polymerase (RdRp) is a promising therapeutic target. Herein, we analyzed amino acid sequence conservation of RdRp across coronaviruses. The conserved amino acids at the catalytic binding site served as the ligand-contacting residues for in silico screening to elucidate possible resistant mutation. Molecular docking was employed to screen inhibitors of SARS-CoV-2 from the ZINC ChemDiv database. The top-ranked compounds selected from GOLD docking were further investigated for binding modes at the conserved residues of RdRp, and ten compounds were selected for experimental validation. Of which, three compounds exhibited promising antiviral activity. The most promising candidate showed a half-maximal effective concentration (EC50) of 5.04 µM. Molecular dynamics simulations, binding free-energy calculation and hydrogen bond analysis were performed to elucidate the critical interactions providing a foundation for developing lead compounds effective against SARS-CoV-2.

The future of dry powder inhaled therapy: Promising or Discouraging for systemic disorders?

Dry powder inhalation therapy has been shown to be an effective method for treating respiratory diseases like asthma, Chronic Obstructive Pulmonary Diseases and Cystic Fibrosis. It has also been widely accepted and used in clinical practices. Such success has led to great interest in inhaled therapy on treating systemic diseases in the past two decades. The current coronavirus (COVID-19) pandemic also has increased such interest and is triggering more potential applications of dry powder inhalation therapy in vaccines and antivirus drugs. Would the inhaled dry powder therapy on systemic disorders be as encouraging as expected? This paper reviews the marketed and in-development dry powder inhaler (DPI) products on the treatment of systemic diseases, their status in clinical trials, as well as the potential for COVID-19 treatment. The advancements and unmet problems on DPI systems are also summarized. With countless attempts behind and more challenges ahead, it is believed that the dry powder inhaled therapy for the treatment of systemic disorders still holds great potential and promise.

In vitro antiviral effects of GS-441524 and itraconazole combination against feline infectious peritonitis virus

Feline infectious peritonitis virus (FIPV: virulent feline coronavirus) causes a fatal disease called feline infectious peritonitis (FIP) in wild and domestic cat species. Recent studies identified several antiviral drugs that are effective against FIPV. Drug combination is one of the important strategies in the development of novel treatments for viral infections. GS-441524, a nucleoside analog, and itraconazole, a triazole antifungal drug, have been reported that have antiviral effect against FIPV. This study aims to investigate whether the combination of GS-441524 and itraconazole has synergic antiviral effect against FIPV. The antiviral effect was measured by plaque reduction assay using felis catus whole fatus-4 cell. The plaque reduction of GS-441524 against type I FIPVs increased as the concentration of itraconazole increased. The similar result was obtained for type II FIPV. In addition, the calculated combination index (CI) demonstrated that there was a strong synergy between GS-441524 and itraconazole. It is concluded that the combination of GS-441524 and itraconazole may enhance the individual effect of each drug against replication of type I FIPVs and may contribute to development more effective treatment strategy for FIP.

JAK2V617F Positive Endothelial Cells Induce Apoptosis and Release JAK2V617F Positive Microparticles

Objective:

Philadelphia chromosome-negative myeloproliferative neoplasms (MPNs) have a high propensity for thrombosis, which has been attributed to increased blood counts, endothelial cell (EC) dysfunction, and inflammation. The presence of the JAK2V617F mutation in the ECs of MPN patients has been confirmed, but the consequences of EC involvement by JAK2V617F in the pathogenesis of thrombosis are unclear. Endothelial microparticles (EMPs) released from ECs play an important role in endothelial dysfunction and also in the intercellular exchange of biological signals and information. Several studies have revealed that patients with JAK2V617F and a thrombosis history have increased numbers of MPs in their circulation.

Materials and Methods:

The current study utilized a lentiviral transduction model of JAK2 wild type (JAK2wt) or JAK2V617F encoding green fluorescent protein (GFP) into human umbilical vein ECs to determine the effect of JAK2V617F on ECs. EC infected with JAK2V617F, JAK2WT, and only-GFP were tested after two days of culture.

Results:

The proteins of ECs that potentially play a role in the development of thrombosis, including endothelial protein C receptor, thrombomodulin, and tissue factor, were detected by flow cytometry analysis with no statistical significance. Increased annexin-V uptake of JAK2V617F and JAK2wt ECs compared to GFP-alone ECs was detected. The EMP production in the supernatants of the EC culture was investigated. Genotyping of the EMPs revealed the presence of genomic DNA and RNA fragments in EMP cargos. JAK2V617F-positive DNA was detected in EMPs released from JAK2V617F-infected ECs and EMPs were shown to carry the genotype of the cell of origin.

Conclusion:

JAK2V617F-positive EMPs were shown for the first time in the literature. This novel research provides the first evidence that EMPs might regulate neighboring and distant cells via their cargo materials. Thus, the direct effect of JAK2V617F on ECs and their functions suggests that different mechanisms might play a role in the pathogenesis of thrombosis in MPNs.

Repurposing the estrogen receptor modulator raloxifene to treat SARS-CoV-2 infection

The ongoing coronavirus disease 2019 (COVID-19) pandemic caused by the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) necessitates strategies to identify prophylactic and therapeutic drug candidates to enter rapid clinical development. This is particularly true, given the uncertainty about the endurance of the immune memory induced by both previous infections or vaccines, and given the fact that the eradication of SARS-CoV-2 might be challenging to reach, given the attack rate of the virus, which would require unusually high protection by a vaccine. Here, we show how raloxifene, a selective estrogen receptor modulator with anti-inflammatory and antiviral properties, emerges as an attractive candidate entering clinical trials to test its efficacy in early-stage treatment COVID-19 patients.

Activation of the SARS-CoV-2 NSP14 3'-5' exoribonuclease by NSP10 and response to antiviral inhibitors

Understanding the core replication complex of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is essential to the development of novel coronavirus-specific antiviral therapeutics. Among the proteins required for faithful replication of the SARS-CoV-2 genome are nonstructural protein 14 (NSP14), a bifunctional enzyme with an N-terminal 3′-to-5′ exoribonuclease (ExoN) and a C-terminal N7-methyltransferase, and its accessory protein, NSP10. The difficulty in producing pure and high quantities of the NSP10/14 complex has hampered the biochemical and structural study of these important proteins. We developed a straightforward protocol for the expression and purification of both NSP10 and NSP14 from Escherichia coli and for the in vitro assembly and purification of a stoichiometric NSP10/14 complex with high yields. Using these methods, we observe that NSP10 provides a 260-fold increase in k_cat/K_m in the exoribonucleolytic activity of NSP14 and enhances protein stability. We also probed the effect of two small molecules on NSP10/14 activity, remdesivir monophosphate and the methyltransferase inhibitor S-adenosylhomocysteine. Our analysis highlights two important factors for drug development: first, unlike other exonucleases, the monophosphate nucleoside analog intermediate of remdesivir does not inhibit NSP14 activity; and second, S-adenosylhomocysteine modestly activates NSP14 exonuclease activity. In total, our analysis provides insights for future structure–function studies of SARS-CoV-2 replication fidelity for the treatment of coronavirus disease 2019.

Scoping insight on antiviral drugs against COVID-19

Background

COVID-19 is an ongoing viral pandemic produced by SARS-CoV-2. In light of in vitro efficacy, several medications were repurposed for its management. During clinical use, many of these medications produced inconsistent results or had varying limitations.

Objective

The purpose of this literature review is to explain the variable efficacy or limitations of Lopinavir/Ritonavir, Remdesivir, Hydroxychloroquine, and Favipiravir in clinical settings.

Method

A study of the literature on the pharmacodynamics (PD), pharmacokinetics (PK), safety profile, and clinical trials through academic databases using relevant search terms.

Results & discussion

The efficacy of an antiviral drug against COVID-19 is associated with its ability to achieve therapeutic concentration in the lung and intestinal tissues. This efficacy depends on the PK properties, particularly protein binding, volume of distribution, and half-life. The PK and PD of the model drugs need to be integrated to predict their limitations.

Conclusion

Current antiviral drugs have varying pharmacological constraints that may associate with limited efficacy, especially in severe COVID-19 patients, or safety concerns.

Thiol drugs decrease SARS-CoV-2 lung injury in vivo and disrupt SARS-CoV-2 spike complex binding to ACE2 in vitro

Neutrophil-induced oxidative stress is a mechanism of lung injury in COVID-19, and drugs with a functional thiol group (“thiol drugs”), especially cysteamine, have anti-oxidant and anti-inflammatory properties that could limit this injury. Thiol drugs may also alter the redox status of the cysteine-rich SARS-CoV-2 spike glycoprotein (SARS-2-S) and thereby disrupt ACE2 binding. Using ACE2 binding assay, reporter virus pseudotyped with SARS-CoV-2 spikes (ancestral and variants) and authentic SARS-CoV-2 (Wuhan-1), we find that multiple thiol drugs inhibit SARS-2-S binding to ACE2 and virus entry into cells. Pseudoviruses carrying variant spikes were less efficiently inhibited as compared to pseudotypes bearing an ancestral spike, but the most potent drugs still inhibited the Delta variant in the low millimolar range. IC50 values followed the order of their cystine cleavage rates and lower thiol pKa values. In hamsters infected with SARS-CoV-2, intraperitoneal (IP) cysteamine decreased neutrophilic inflammation and alveolar hemorrhage in the lungs but did not decrease viral infection, most likely because IP delivery could not achieve millimolar concentrations in the airways. These data show that thiol drugs inhibit SARS-CoV-2 infection in vitro and reduce SARS-CoV-2-related lung injury in vivo and provide strong rationale for trials of systemically delivered thiol drugs as COVID-19 treatments. We propose that antiviral effects of thiol drugs in vivo will require delivery directly to the airways to ensure millimolar drug concentrations and that thiol drugs with lower thiol pKa values are most likely to be effective.

The effect of cysteamine to decrease SARS-CoV-2 pneumonia in vivo and of multiple thiol drugs to inhibit SARS-CoV-2 infection in vitro provides rationale for clinical trials of thiol drugs in COVID-19.

Liposomal remdesivir inhalation solution for targeted lung delivery as a novel therapeutic approach for COVID-19

Strong infectivity enables coronavirus disease 2019 (COVID-19) to rage throughout the world. Moreover, the lack of drugs with definite therapeutic effects further aggravates the spread of the pandemic. Remdesivir is one of the most promising anti-severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) drugs. However, the limited clinical effects make its therapeutic effect controversial, which may result from the poor accumulation and activation of remdesivir in the lung. Therefore, we developed lyophilized remdesivir liposomes (Rdv-lips) which can be reconstituted as liposomal aerosol for pulmonary delivery to improve the in vivo behavior of existing remdesivir cyclodextrin conclusion compound (Rdv-cyc) injections. Liposome encapsulation endowed remdesivir with much higher solubility and better biocompatibility. The in vitro liposomal aerosol characterization demonstrated that Rdv-lips possessed a mass median aerodynamic diameter of 4.118 µm and fine particle fraction (<5 µm) higher than 50%, indicating good pulmonary delivery properties. Compared to the Rdv-cyc intravenous injection group, the Rdv-lips inhalation group displayed a nearly 100-fold increase in the remdesivir-active metabolite nucleotide triphosphate (NTP) concentration and better NTP accumulation in the lung than the Rdv-cyc inhalation group. A faster transition from remdesivir to NTP of Rdv-lips (inhalation) could also be observed due to better cell uptake. Compared to other preparations, the superiority of Rdv-lips was further evidenced by the results of an in vivo safety study, with little possibility of inducing inflammation. In conclusion, Rdv-lips for pulmonary delivery will be a potent formulation to improve the in vivo behavior of remdesivir and exert better therapeutic effects in COVID-19 treatment.

Screening a Library of FDA-Approved and Bioactive Compounds for Antiviral Activity against SARS-CoV-2

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent of coronavirus disease 2019 (COVID-19), has emerged as a major global health threat. The COVID-19 pandemic has resulted in over 168 million cases and 3.4 million deaths to date, while the number of cases continues to rise. With limited therapeutic options, the identification of safe and effective therapeutics is urgently needed. The repurposing of known clinical compounds holds the potential for rapid identification of drugs effective against SARS-CoV-2. Here, we utilized a library of FDA-approved and well-studied preclinical and clinical compounds to screen for antivirals against SARS-CoV-2 in human pulmonary epithelial cells. We identified 13 compounds that exhibit potent antiviral activity across multiple orthogonal assays. Hits include known antivirals, compounds with anti-inflammatory activity, and compounds targeting host pathways such as kinases and proteases critical for SARS-CoV-2 replication. We identified seven compounds not previously reported to have activity against SARS-CoV-2, including B02, a human RAD51 inhibitor. We further demonstrated that B02 exhibits synergy with remdesivir, the only antiviral approved by the FDA to treat COVID-19, highlighting the potential for combination therapy. Taken together, our comparative compound screening strategy highlights the potential of drug repurposing screens to identify novel starting points for development of effective antiviral mono- or combination therapies to treat COVID-19.

Remdesivir for the treatment of COVID-19

BACKGROUND

Remdesivir is an antiviral medicine with properties to inhibit viral replication of SARS-CoV-2. Positive results from early studies attracted media attention and led to emergency use authorisation of remdesivir in COVID-19.  A thorough understanding of the current evidence regarding the effects of remdesivir as a treatment for SARS-CoV-2 infection based on randomised controlled trials (RCTs) is required.

OBJECTIVES

To assess the effects of remdesivir compared to placebo or standard care alone on clinical outcomes in hospitalised patients with SARS-CoV-2 infection, and to maintain the currency of the evidence using a living systematic review approach.

SEARCH METHODS

We searched the Cochrane COVID-19 Study Register (which comprises the Cochrane Central Register of Controlled Trials (CENTRAL), PubMed, Embase, ClinicalTrials.gov, WHO International Clinical Trials Registry Platform, and medRxiv) as well as Web of Science (Science Citation Index Expanded and Emerging Sources Citation Index) and WHO COVID-19 Global literature on coronavirus disease to identify completed and ongoing studies without language restrictions. We conducted the searches on 16 April 2021.

SELECTION CRITERIA

We followed standard Cochrane methodology. We included RCTs evaluating remdesivir for the treatment of SARS-CoV-2 infection in hospitalised adults compared to placebo or standard care alone irrespective of disease severity, gender, ethnicity, or setting.  We excluded studies that evaluated remdesivir for the treatment of other coronavirus diseases.

DATA COLLECTION AND ANALYSIS

We followed standard Cochrane methodology. To assess risk of bias in included studies, we used the Cochrane RoB 2 tool for RCTs. We rated the certainty of evidence using the GRADE approach for outcomes that were reported according to our prioritised categories: all-cause mortality at up to day 28, duration to liberation from invasive mechanical ventilation, duration to liberation from supplemental oxygen, new need for mechanical ventilation (high-flow oxygen or non-invasive or invasive mechanical ventilation), new need for invasive mechanical ventilation, new need for non-invasive mechanical ventilation or high-flow oxygen, new need for oxygen by mask or nasal prongs, quality of life, adverse events (any grade), and serious adverse events.

MAIN RESULTS

We included five RCTs with 7452 participants diagnosed with SARS-CoV-2 infection and a mean age of 59 years, of whom 3886 participants were randomised to receive remdesivir. Most participants required low-flow oxygen (n=4409) or mechanical ventilation (n=1025) at baseline. We identified two ongoing studies, one was suspended due to a lack of COVID-19 patients to recruit. Risk of bias was considered to be of some concerns or high risk for clinical status and safety outcomes because participants who had died did not contribute information to these outcomes. Without adjustment, this leads to an uncertain amount of missing values and the potential for bias due to missing data. Effects of remdesivir in hospitalised individuals  Remdesivir probably makes little or no difference to all-cause mortality at up to day 28 (risk ratio (RR) 0.93, 95% confidence interval (CI) 0.81 to 1.06; risk difference (RD) 8 fewer per 1000, 95% CI 21 fewer to 7 more; 4 studies, 7142 participants; moderate-certainty evidence). Considering the initial severity of condition, only one study showed a beneficial effect of remdesivir in patients who received low-flow oxygen at baseline (RR 0.32, 95% CI 0.15 to 0.66, 435 participants), but conflicting results exists from another study, and we were unable to validly assess this observations due to limited availability of comparable data. Remdesivir may have little or no effect on the duration to liberation from invasive mechanical ventilation (2 studies, 1298 participants, data not pooled, low-certainty evidence). We are uncertain whether remdesivir increases or decreases the chance of clinical improvement in terms of duration to liberation from supplemental oxygen at up to day 28 (3 studies, 1691 participants, data not pooled, very low-certainty evidence).   We are very uncertain whether remdesivir decreases or increases the risk of clinical worsening in terms of new need for mechanical ventilation at up to day 28 (high-flow oxygen or non-invasive ventilation or invasive mechanical ventilation) (RR 0.78, 95% CI 0.48 to 1.24; RD 29 fewer per 1000, 95% CI 68 fewer to 32 more; 3 studies, 6696 participants; very low-certainty evidence); new need for non-invasive mechanical ventilation or high-flow oxygen (RR 0.70, 95% CI 0.51 to 0.98; RD 72 fewer per 1000, 95% CI 118 fewer to 5 fewer; 1 study, 573 participants; very low-certainty evidence); and new need for oxygen by mask or nasal prongs (RR 0.81, 95% CI 0.54 to 1.22; RD 84 fewer per 1000, 95% CI 204 fewer to 98 more; 1 study, 138 participants; very low-certainty evidence). The evidence suggests that remdesivir may decrease the risk of clinical worsening in terms of new need for invasive mechanical ventilation (67 fewer participants amongst 1000 participants; RR 0.56, 95% CI 0.41 to 0.77; 2 studies, 1159 participants; low-certainty evidence).  None of the included studies reported quality of life. Remdesivir probably decreases the serious adverse events rate at up to 28 days (RR 0.75, 95% CI 0.63 to 0.90; RD 63 fewer per 1000, 95% CI 94 fewer to 25 fewer; 3 studies, 1674 participants; moderate-certainty evidence). We are very uncertain whether remdesivir increases or decreases adverse events rate (any grade) (RR 1.05, 95% CI 0.86 to 1.27; RD 29 more per 1000, 95% CI 82 fewer to 158 more; 3 studies, 1674 participants; very low-certainty evidence).

AUTHORS' CONCLUSIONS

Based on the currently available evidence, we are moderately certain that remdesivir probably has little or no effect on all-cause mortality at up to day 28 in hospitalised adults with SARS-CoV-2 infection. We are uncertain about the effects of remdesivir on clinical improvement and worsening. There were insufficient data available to validly examine the effect of remdesivir on mortality in subgroups depending on the extent of respiratory support at baseline.  Future studies should provide additional data on efficacy and safety of remdesivir for defined core outcomes in COVID-19 research, especially for different population subgroups. This could allow us to draw more reliable conclusions on the potential benefits and harms of remdesivir in future updates of this review. Due to the living approach of this work, we will update the review periodically.

Griffithsin and Carrageenan Combination Results in Antiviral Synergy against SARS-CoV-1 and 2 in a Pseudoviral Model

Over 182 million confirmed cases of COVID-19 and more than 4 million deaths have been reported to date around the world. It is essential to identify broad-spectrum antiviral agents that may prevent or treat infections by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) but also by other coronaviruses that may jump the species barrier in the future. We evaluated the antiviral selectivity of griffithsin and sulfated and non-sulfated polysaccharides against SARS-CoV-1 and SARS-CoV-2 using a cytotoxicity assay and a cell-based pseudoviral model. The half-maximal cytotoxic concentration (CC₅₀) and half-maximal effective concentration (EC₅₀) were determined for each compound, using a dose-response-inhibition analysis on GraphPad Prism v9.0.2 software (San Diego, CA, USA). The therapeutic index (TI = CC₅₀/EC₅₀) was calculated for each compound. The potential synergistic, additive, or antagonistic effect of different compound combinations was determined by CalcuSyn v1 software (Biosoft, Cambridge, UK), which estimated the combination index (CI) values. Iota and lambda carrageenan showed the most potent antiviral activity (EC₅₀ between 3.2 and 7.5 µg/mL). Carrageenan and griffithsin combinations exhibited synergistic activity (EC₅₀ between 0.2 and 3.8 µg/mL; combination index <1), including against recent SARS-CoV-2 mutations. The griffithsin and carrageenan combination is a promising candidate to prevent or treat infections by SARS-CoV-1 and SARS-CoV-2.

ADME and Pharmacokinetic Properties of Remdesivir: Its Drug Interaction Potential

On 11 March 2020, the World Health Organization (WHO) classified the Coronavirus Disease 2019 (COVID-19) as a global pandemic, which tested healthcare systems, administrations, and treatment ingenuity across the world. COVID-19 is caused by the novel beta coronavirus Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2). Since the inception of the pandemic, treatment options have been either limited or ineffective. Remdesivir, a drug originally designed to be used for Ebola virus, has antiviral activity against SARS-CoV-2 and has been included in the COVID-19 treatment regimens. Remdesivir is an adenosine nucleotide analog prodrug that is metabolically activated to a nucleoside triphosphate metabolite (GS-443902). The active nucleoside triphosphate metabolite is incorporated into the SARS-CoV-2 RNA viral chains, preventing its replication. The lack of reported drug development and characterization studies with remdesivir in public domain has created a void where information on the absorption, distribution, metabolism, elimination (ADME) properties, pharmacokinetics (PK), or drug-drug interaction (DDI) is limited. By understanding these properties, clinicians can prevent subtherapeutic and supratherapeutic levels of remdesivir and thus avoid further complications in COVID-19 patients. Remdesivir is metabolized by both cytochrome P450 (CYP) and non-CYP enzymes such as carboxylesterases. In this narrative review, we have evaluated the currently available ADME, PK, and DDI information about remdesivir and have discussed the potential of DDIs between remdesivir and different COVID-19 drug regimens and agents used for comorbidities. Considering the nascent status of remdesivir in the therapeutic domain, extensive future work is needed to formulate safer COVID-19 treatment guidelines involving this medication.

A Mini Review on Discovery and Synthesis of Remdesivir as an Effective and Promising Drug against COVID-19

The severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) as a new human coronavirus has begun spreading over Wuhan City/China in December 2019, and then spread rapidly worldwide, causing pneumonia called COVID-19. Up to now, the scientists have extensively attempted to find effective vaccines and drugs for treatment of coronavirus infections. To this end, various pharmaceutical agents are undergoing the clinical studies to assess their potency and efficacy against COVID-19. Based on the new findings, the U.S. food and drug administration (FDA) has issued an emergency use authorization for remdesivir as an effective anti-viral for remedying the hospitalized COVID-19 patients. Recently, the European medicines agency has authorized the use of remdesivir for the treatment of COVID-19. Remdesivir as a nucleotide prodrug exhibits broad-spectrum antiviral activities against RNA viruses. In this short review, we have rendered a brief overview of discovery and synthesis for remdesivir.

Remdesivir in Coronavirus Disease 2019 (COVID-19) treatment: a review of evidence

COVID-19 is an infectious disease caused by a novel β-coronavirus, belonging to the same subgenus as the Severe Acute Respiratory Syndrome (SARS) virus. Remdesivir, an investigational broad-spectrum antiviral agent has previously demonstrated in vitro activity against Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), and in vivo efficacy against other related coronaviruses in animal models. Its safety profile has been tested in a compassionate use setting for patients with COVID-19. The current therapeutic studies demonstrate clinical effectiveness of remdesivir in COVID-19 patients by shortening time to clinical recovery, and hospital stay. In this review, we critically analyze the current evidence of remdesivir against COVID-19 and dissect the aspects over its safety and efficacy. Based on existing data, remdesivir can be regarded as a potential therapeutic agent against COVID-19. Further large-scale, randomized placebo-controlled clinical trials are, however, awaited to validate these findings.