Bench-to-bedside: Innovation of small molecule anti-SARS-CoV-2 drugs in China

Game Changers: Blockbuster Small-Molecule Drugs Approved by the FDA in 2024

This article profiles 27 innovative advancements in small-molecule drugs approved by the U.S. Food and Drug Administration (FDA) in 2024. These drugs target various therapeutic areas including non-small cell lung cancer, advanced or metastatic breast cancer, glioma, relapsed or refractory acute leukemia, urinary tract infection, Staphylococcus aureus bloodstream infections, nonalcoholic steatohepatitis, primary biliary cholangitis, Duchenne muscular dystrophy, hypertension, anemia due to chronic kidney disease, extravascular hemolysis, primary axillary hyperhidrosis, chronic obstructive pulmonary disease, severe alopecia areata, WHIM syndrome, Niemann-Pick disease type C, schizophrenia, supraventricular tachycardia, congenital adrenal hyperplasia, and cystic fibrosis. Among these approved small-molecule drugs, those with unique mechanisms of action and designated as breakthrough therapies by the FDA represent a significant proportion, highlighting ongoing innovation. Notably, eight of these drugs (including Rezdiffra®, Voydeya®, Iqirvo®, Voranigo®, Livdelzi®, Miplyffa®, Revuforj®, and Crenessity®) are classified as "first-in-class" and have received breakthrough therapy designation. These agents not only exhibit distinct mechanisms of action but also offer substantial improvements in efficacy for patients compared to prior therapeutic options. This article offers a comprehensive analysis of the mechanisms of action, clinical trials, drug design, and synthetic methodologies related to representative drugs, aiming to provide crucial insights for future pharmaceutical development.

Effectiveness and safety of azvudine versus nirmatrelvir/ritonavir in hospitalized patients with COVID-19

PURPOSE

To compare the effectiveness and safety of two antiviral drugs, azvudine and nirmatrelvir/ritonavir, in treating hospitalized patients with COVID-19.

METHODS

We conducted a retrospective analysis of patients who were admitted to the First Affiliated Hospital of Soochow University and diagnosed with SARS-CoV-2 infection between December 2022 and February 2023. These patients were treated with either azvudine or nirmatrelvir/ritonavir.

RESULTS

The study initially included a total of 1097 patients. After applying a 1:3 propensity score matching, we ultimately included 728 patients, comprising 521 recipients of azvudine and 207 recipients of nirmatrelvir/ritonavir. Among them, 463 patients (88.9%) in the azvudine group and 182 patients (87.9%) in the nirmatrelvir/ritonavir group achieved recovery and discharge, with no significant difference between the two groups (P = 0.816). The median time of improvement was 5.5 days (3.3, 9.0) in the nirmatrelvir/ritonavir group and 5.0 days (4.0, 8.0) in the azvudine group, with no significant difference observed between the two groups (P = 0.732). Furthermore, no significant differences were noted in terms of the time to fever resolution in patients with fever (P = 0.547), the rates of usage of high-flow nasal cannula (P = 0.054), non-invasive mechanical ventilation (P = 0.531), and invasive mechanical ventilation (P = 0.667), the duration of invasive mechanical ventilation usage (P = 0.732), the rate of disease progression (P = 0.602), and hospital length of stay (P = 0.884). Regarding safety outcomes, there was a notable increase in the occurrence of myocardial injury in the nirmatrelvir/ritonavir group (13.5%) compared to the azvudine group (7.3%) (P = 0.012). The two groups did not exhibit differences in the incidence of other adverse events.

CONCLUSION

In hospitalized patients with COVID-19, the effectiveness of azvudine and nirmatrelvir/ritonavir was found to be comparable in various aspects, including the improved discharge rate, the improvement time, time to fever resolution, usage rates of high-flow nasal cannula, non-invasive mechanical ventilation, and invasive mechanical ventilation, rate of disease progression, time to discharge, and hospital length of stay. The occurrence of myocardial injury was higher in nirmatrelvir/ritonavir group compared to azvudine group, while no significant differences were observed in other adverse reactions.

Advances in the effectiveness and safety of azvudine treatment: a comprehensive review

The global impact of COVID-19 has highlighted the urgent need for effective therapeutic interventions against SARS-CoV-2. Azvudine, a dual-target nucleoside drug initially developed for human immunodeficiency virus (HIV), has gained attention for its potential in treating COVID-19. On 25 July 2022, Azvudine received conditional approval from the National Medical Products Administration (NMPA) of China, making it the first oral SARS-CoV-2 RNA-dependent RNA polymerase (RdRp) inhibitor for COVID-19 treatment. This review explores the pharmacological activity, antiviral mechanisms, and clinical effectiveness of azvudine in the context of COVID-19. Clinical trials have demonstrated its ability to reduce the viral load, shorten the time to nucleic acid negativity, and improve clinical outcomes in patients. Additionally, azvudine has shown excellent pharmacokinetic properties and a favorable safety profile with mild side effects. The review also addresses the importance of drug interactions and safety considerations, particularly in high-risk populations. Research should focus on optimizing second-generation inhibitors with enhanced effectiveness against SARS-CoV-2 variants, improving oral bioavailability, and minimizing adverse effects, ensuring more robust treatment options for COVID-19.

A multicenter, real-world cohort study: effectiveness and safety of Azvudine in hospitalized COVID-19 patients with pre-existing diabetes

Introduction

During the Omicron infection wave, diabetic patients are susceptible to COVID-19, which is linked to a poor prognosis. However, research on the real-world effectiveness and safety of Azvudine, a common medication for COVID-19, is insufficient in those with pre-existing diabetes.

Methods

In this retrospective study, we included 32,864 hospitalized COVID-19 patients from 9 hospitals in Henan Province. Diabetic patients were screened and divided into the Azvudine group and the control group, via 1:1 propensity score matching. The primary outcome was all-cause mortality, and the secondary outcome was composite disease progression. Laboratory abnormal results were used for safety evaluation.

Results

A total of 1,417 patients receiving Azvudine and 1,417 patients receiving standard treatment were ultimately included. Kaplan-Meier curves suggested that all-cause mortality (P = 0.0026) was significantly lower in the Azvudine group than in the control group, but composite disease progression did not significantly differ (P = 0.1). Cox regression models revealed Azvudine treatment could reduce 26% risk of all-cause mortality (95% CI: 0.583-0.942, P = 0.015) versus controls, and not reduce the risk of composite disease progression (HR: 0.91, 95% CI: 0.750-1.109, P = 0.355). The results of subgroup analysis and three sensitivity analyses were consistent with the previous findings. Safety analysis revealed that the incidence rates of most adverse events were similar between the two groups.

Conclusion

In this study, Azvudine demonstrated good efficacy in COVID-19 patients with diabetes, with a lower all-cause mortality rate. Additionally, the safety was favorable. This study may provide a new strategy for the antiviral management of COVID-19 patients with diabetes.

Drug repurposing of argatroban, glimepiride and ranolazine shows anti-SARS-CoV-2 activity via diverse mechanisms

Despite the vast vaccination campaigns against SARS-CoV-2, vaccine-resistant variants have emerged, and COVID-19 is continuing to spread with the fear of emergence of new variants that are resistant to the currently available anti-viral drugs. Hence, there is an urgent need to discover potential host-directed - rather than virus-directed - therapies against COVID-19. SARS-CoV-2 enters host cells through binding of the viral spike (S)-protein to the host angiotensin-converting enzyme 2 (ACE2) receptor, rendering the viral port of entry an attractive therapeutic target. Accordingly, this study aimed to investigate FDA-approved drugs for their potential repurposing to inhibit the entry point of SARS-CoV-2. Accordingly, the FDA-approved drugs library was enrolled in docking simulations to identify drugs that bind to the Spike-ACE2 interface. The drugs list retrieved by the docking simulations was shortlisted to 19 drugs based on docking scores and safety profiles. These drugs were screened for their ability to prevent binding between ACE2 and S-protein using an ELISA-based Spike-ACE2 binding assay. Five drugs showed statistically significant inhibition of binding between ACE2 and S-protein, ranging from 4 % to 37 %. Of those five, argatroban, glimepiride and ranolazine showed potential antiviral activity at IC50 concentrations well below their CC50 assessed by the plaque assay. Their mode of antiviral action was then determined using the plaque assay with some modifications, which revealed that argatroban acted mainly through a direct virucidal mechanism, while glimepiride largely inhibited viral replication, and ranolazine exerted its antiviral impact primarily through inhibiting viral adsorption. In conclusion, this study has identified three FDA-approved drugs - argatroban, glimepiride and ranolazine - which could potentially be repurposed and used for the management of COVID-19.

Research Progress on the Structure and Function, Immune Escape Mechanism, Antiviral Drug Development Methods, and Clinical Use of SARS-CoV-2 Mpro

The three-year COVID-19 pandemic 'has' caused a wide range of medical, social, political, and financial implications. Since the end of 2020, various mutations and variations in SARS-CoV-2 strains, along with the immune escape phenomenon, have emerged. There is an urgent need to identify a relatively stable target for the development of universal vaccines and drugs that can effectively combat both SARS-CoV-2 strains and their mutants. Currently, the main focus in treating SARS-CoV-2 lies in disrupting the virus's life cycle. The main protease (Mpro) is closely associated with virus replication and maturation and plays a crucial role in the early stages of infection. Consequently, it has become an important target for the development of SARS-CoV-2-specific drugs. This review summarizes the recent research progress on the novel coronavirus's main proteases, including the pivotal role of Mpro in the virus's life cycle, the structure and catalytic mechanism of Mpro, the self-maturation mechanism of Mpro, the role of Mpro in virus immune escape, the current methods of developing antiviral drugs targeting Mpro, and the key drugs that have successfully entered clinical trials. The aim is to provide researchers involved in the development of antiviral drugs targeting Mpro with systematic and comprehensive information.

Herbal Medicines as Complementary Therapy for Managing Complications in COVID-19 Patients with Diabetes Mellitus

Diabetes mellitus (DM) is recognized and classified as a group of conditions marked by persistent high blood glucose levels. It is also an inflammatory condition that may influence concurrent disease states, including Coronavirus Disease 2019 (COVID-19). Currently, no effective drug has been found to treat COVID-19, especially in DM patients. Many herbal medicines, such as the well-known Andrographis paniculata, have been explored as drugs and complementary therapies due to their antidiabetic, antibacterial, antiviral, anti-inflammatory, and immunomodulatory effects. This study aimed to examine the potential of herbal medicines as complementary therapy in DM patients with COVID-19 complications, drawing from in-vitro and in-vivo investigations. This study analyzed articles published within the last 15 years using keywords including "herbal medicines", "COVID-19", "Diabetes Mellitus", "antidiabetics", "antiviral", and "anti-inflammatory". The results showed that several herbal medicines could serve as complementary therapy for DM patients with COVID-19 complications. These include Andrographis paniculata, Ageratum conyzoides, Artocarpus altilis, Centella asiatica, Momordica charantia, Persea gratissima, Phyllanthus urinaria, Physalis angulata, Tinospora cordifolia, and Zingiber zerumbet. Herbal medicines may serve as a complementary therapy for DM patients with COVID-19, but these claims need experimental validation in infection models and among affected patients.

Eco-sustainable chromatographic method for the determination of favipiravir and nitazoxanide for COVID-19: application to human plasma

Coronavirus disease 2019 (COVID-19), an extremely contagious illness, has posed enormous challenges to healthcare systems around the world. Although the evidence on COVID-19 management is growing, antiviral medication is still the first line of treatment. Therefore, it is critical that effective, safe, and tolerable antivirals be available to treat early COVID-19 and stop its progression. Recently, favipiravir (FAV) has received FDA approval as safe and effective antiviral medication for COVID-19 management. Nitazoxanide (NTZ) also possesses antiviral and immunomodulating activities. Moreover, FAV and NTZ in combination are clinically used in COVID-19 treatment with reported safety, synergistic antiviral and immunomodulating effects. Despite the availability of various clinical studies on both FAV and NTZ, no existing analytical application for the simultaneous estimation of FAV and NTZ exists. As a result, the current work goal is to establish a green HPLC method for their analysis and implementation to human plasma. The developed method utilizes isocratic elution with 0.1% aqueous formic acid: ethanol (55:45, v/v) and dantrolene as internal standard. The bioanalytical validation parameters passed the FDA acceptance criteria. NEMI, eco scale, AGREE and ComplexGAPI approaches were used for qualitative and quantitative evaluation of the method's greenness.

Effect of SARS-CoV-2 infection on liver function in patients with hepatitis B

OBJECTIVE

To investigate the impact of SARS-CoV-2 infection on liver function and prognosis in patients with HBV infection.

METHODS

A total of 154 HBV-positive patients (HBV ( +) group) and 154 HBV-negative patients (HBV (-) group) diagnosed with COVID-19 at Taizhou Hospital between December 10, 2022, and January 31, 2023, were included in this study. Clinical characteristics, treatment, and laboratory findings were collected from patients at three time points: before (T1), during (T2), and at the time of discharge (T3) from SARS-CoV-2 infection.

RESULTS

Compared to the HBV (-) group, the HBV ( +) group had a longer hospital stay (15 (9-22) days vs. 9 (5-16) days). Longitudinal comparisons of laboratory indicators from T1 to T3 showed a continuous decline in TP and ALB levels and a continuous increase in PT and TT levels in the HBV ( +) group. BUN levels increased during T2 and decreased thereafter. These differences were considered statistically significant (P < 0.05). Notably, the HBV ( +) group had a higher proportion of indicators elevated > 3 ULN from T1 to T2, including ALT (1.95%/5.19%), AST (3.25%/12.99%), ALP (1.95%/3.25%), GGT (4.55%/9.09%), TBIL (6.49%/9.09%), and DBIL (18.18%/22.73%). In the HBV (-) group, the elevations were mainly concentrated within 1-2 ULN, including AST (12.99%/22.08%), DBIL (10.39%/21.43%), BUN (12.99%/22.08%), CREA (20.13%/29.22%), and PLT (7.79%/14.94%). Furthermore, the incidence of liver injury from T1 to T3 was higher in the HBV ( +) group compared to the HBV (-) group (15.7% (20/127) vs. 7.2% (11/152), P < 0.05). Multivariate analysis showed that liver cirrhosis (HR = 4.847, 95% CI: 1.224-19.20, P = 0.025) and liver cancer (HR = 8.333, 95% CI: 2.156-32.209, P = 0.002) were independent risk factors for liver injury in the presence of SARS-CoV-2 infection.

CONCLUSION

SARS-CoV-2 infection has a higher proportion of liver injury in HBV-infected patients, affecting hepatic protein synthesis function. Those with cirrhosis and hepatocellular carcinoma are at higher risk of severe liver injury.

The Impact of Traditional Chinese Herbal Decoctions Combined with Rehabilitation Therapy on Pulmonary Function and Respiratory Muscle Strength in COVID-19 Recovery Patients

Objective

This study aims to evaluate the clinical efficacy of integrated traditional Chinese and Western medicine rehabilitation treatment during the recovery period of COVID-19, providing a scientific basis for developing more effective rehabilitation protocols.

Methods

The study included 120 COVID-19 (novel coronavirus) recovery patients treated at our hospital from November 2021 to April 2022. After registration, patients were randomly divided into two groups, namely the study group and the control group. The control group received conventional rehabilitation treatment, while the study group underwent integrated traditional Chinese and Western medicine rehabilitation treatment, with 60 cases in each group. The clinical observation indicators in this study include the results of the 6-minute walk test (6MWT), respiratory and circulatory parameters, pulmonary function, changes in respiratory muscle strength, and quality of life in both groups of patients.

Results

The 6MWT distance increased significantly in both groups, with the study group showing a larger improvement (P < 0.05). SpO2 and PaO2 values improved significantly in both groups, with greater increases in the study group (P < 0.05). Lung function parameters (FEV1 and FEV1/FVC) improved significantly in the study group compared to the control group (P < 0.05). Diaphragmatic thickness and mobility were also significantly higher in the study group (P < 0.05). The SF-36 quality of life scores were significantly better in the study group (P < 0.05).

Conclusion

Integrated traditional Chinese and Western medicine rehabilitation treatment has achieved significant efficacy during the recovery period of COVID-19. The complementary use of traditional Chinese medicine's differential diagnosis and treatment and modern medical approaches from Western medicine provides patients with comprehensive and personalized rehabilitation services, offering new ideas and methods to improve the quality of patient recovery.

Efficacy of Azvudine Therapy in Patients with Severe and Non-Severe COVID-19: A Propensity Score-Matched Analysis

Objective

Azvudine is used to treat patients with the coronavirus disease 2019 (COVID-19). This study evaluated the clinical efficacy of azvudine in hospitalized patients with different severities of COVID-19 because few studies have described this in patients with severe and non-severe COVID-19.

Methods

This retrospective study included hospitalized patients with COVID-19 in Guizhou Provincial People's Hospital between December 2022 and January 2023. Azvudine-treated patients and controls were matched for sex, age, and disease severity at admission. Laboratory results and outcomes, including all-cause mortality, invasive mechanical ventilation, intensive care unit admission, and hospital stay length, were evaluated. Stratified analysis was used to explore the difference in the efficacy of azvudine in severe and non-severe COVID-19 patients.

Results

No significant differences in all-cause mortality were observed between the 303 azvudine recipients and 303 matched controls. However, azvudine-treated patients had shorter hospital stays (8.34±4.79 vs 9.17±6.25 days, P=0.046) and higher lymphocyte improvement rates (21.5% vs 13.9%, P=0.019), with a more pronounced effect in patients with non-severe COVID-19 (length of hospital stay, 8.07±4.35 vs 10.00±6.29 days, P=0.001; lymphocyte improvement rate, 23.8% vs 12.8%, P=0.015).

Conclusion

Azvudine treatment shortens hospital stay length and increases the rate of lymphocyte count improvement in patients with non-severe COVID-19, suggesting that azvudine may be a treatment option for these patients.

SARS-CoV-2 replication and drug discovery

The coronavirus disease 2019 (COVID-19) caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has killed millions of people and continues to wreak havoc across the globe. This sudden and deadly pandemic emphasizes the necessity for anti-viral drug development that can be rapidly administered to reduce morbidity, mortality, and virus propagation. Thus, lacking efficient anti-COVID-19 treatment, and especially given the lengthy drug development process as well as the critical death tool that has been associated with SARS-CoV-2 since its outbreak, drug repurposing (or repositioning) constitutes so far, the ideal and ready-to-go best approach in mitigating viral spread, containing the infection, and reducing the COVID-19-associated death rate. Indeed, based on the molecular similarity approach of SARS-CoV-2 with previous coronaviruses (CoVs), repurposed drugs have been reported to hamper SARS-CoV-2 replication. Therefore, understanding the inhibition mechanisms of viral replication by repurposed anti-viral drugs and chemicals known to block CoV and SARS-CoV-2 multiplication is crucial, and it opens the way for particular treatment options and COVID-19 therapeutics. In this review, we highlighted molecular basics underlying drug-repurposing strategies against SARS-CoV-2. Notably, we discussed inhibition mechanisms of viral replication, involving and including inhibition of SARS-CoV-2 proteases (3C-like protease, 3CLpro or Papain-like protease, PLpro) by protease inhibitors such as Carmofur, Ebselen, and GRL017, polymerases (RNA-dependent RNA-polymerase, RdRp) by drugs like Suramin, Remdesivir, or Favipiravir, and proteins/peptides inhibiting virus-cell fusion and host cell replication pathways, such as Disulfiram, GC376, and Molnupiravir. When applicable, comparisons with SARS-CoV inhibitors approved for clinical use were made to provide further insights to understand molecular basics in inhibiting SARS-CoV-2 replication and draw conclusions for future drug discovery research.

The Next Generation COVID-19 Antiviral; Niclosamide-Based Inorganic Nanohybrid System Kills SARS-CoV-2

The coronavirus disease 2019 (COVID-19) pandemic is a serious global threat with surging new variants of concern. Although global vaccinations have slowed the pandemic, their longevity is still unknown. Therefore, new orally administrable antiviral agents are highly demanded. Among various repurposed drugs, niclosamide (NIC) is the most potential one for various viral diseases such as COVID-19, SARS (severe acute respiratory syndrome), MERS (middle east respiratory syndrome), influenza, RSV (respiratory syncytial virus), etc. Since NIC cannot be effectively absorbed, a required plasma concentration for antiviral potency is hard to maintain, thereby restricting its entry into the infected cells. Such a 60-year-old bioavailability challenging issue has been overcome by engineering with MgO and hydroxypropyl methylcellulose (HPMC), forming hydrophilic NIC-MgO-HPMC, with improved intestinal permeability without altering NIC metabolism as confirmed by parallel artificial membrane permeability assay. The inhibitory effect on SARS-CoV-2  replication is confirmed in the Syrian hamster model to reduce lung injury. Clinical studies reveal that the bioavailability of NIC hybrid drug can go 4 times higher than the intact NIC. The phase II clinical trial shows a dose-dependent bioavailability of NIC from hybrid drug  suggesting its potential applicability as a game changer in achieving the much-anticipated endemic phase.

SARS-CoV-2 Mpro inhibitor identification using a cellular gain-of-signal assay for high-throughput screening

Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2, SARS2) is responsible for the COVID-19 pandemic and infections that continue to affect the lives of millions of people worldwide, especially those who are older and/or immunocompromised. The SARS2 main protease enzyme, Mpro (also called 3C-like protease, 3CLpro), is a bona fide drug target as evidenced by potent inhibition with nirmatrelvir and ensitrelvir, the active components of the drugs Paxlovid and Xocova, respectively. However, the existence of nirmatrelvir and ensitrelvir-resistant isolates underscores the need to develop next-generation drugs with different resistance profiles and/or distinct mechanisms of action. Here, we report the results of a high-throughput screen of 649,568 compounds using a cellular gain-of-signal assay. In this assay, Mpro inhibits expression of a luciferase reporter, and 8,777 small molecules were considered hits by causing a gain in luciferase activity 3x SD above the sample field activity (6.8% gain-of-signal relative to 100 µM GC376). Single concentration and dose-response gain-of-signal experiments confirmed 3,522/8,762 compounds as candidate inhibitors. In parallel, all initial high-throughput screening hits were tested in a peptide cleavage assay with purified Mpro and only 39/8,762 showed inhibition. Importantly, 19/39 compounds (49%) re-tested positive in both SARS2 assays, including two previously reported Mpro inhibitors, demonstrating the efficacy of the overall screening strategy. This approach led to the rediscovery of known Mpro inhibitors such as calpain inhibitor II, as well as to the discovery of novel compounds that provide chemical information for future drug development efforts.

Obesity-compromised immunity in post-COVID-19 condition: a critical control point of chronicity

Post-COVID-19 condition is recognized as a multifactorial disorder, with persistent presence of viral antigens, discordant immunity, delayed viral clearance, and chronic inflammation. Obesity has emerged as an independent risk factor for both SARS-CoV-2 infection and its subsequent sequelae. In this study, we aimed to predict the molecular mechanisms linking obesity and post-COVID-19 distress. Viral antigen-exposed adipose tissues display remarkable levels of viral receptors, facilitating viral entry, deposition, and chronic release of inflammatory mediators and cells in patients. Subsequently, obesity-associated inflammatory insults are predicted to disturb cellular and humoral immunity by triggering abnormal cell differentiation and lymphocyte exhaustion. In particular, the decline in SARS-CoV-2 antibody titers and T-cell exhaustion due to chronic inflammation may account for delayed virus clearance and persistent activation of inflammatory responses. Taken together, obesity-associated defective immunity is a critical control point of intervention against post-COVID-19 progression, particularly in subjects with chronic metabolic distress.

Paxlovid reduces the 28-day mortality of patients with COVID-19: a retrospective cohort study

PURPOSE

In this study, we aim to explore the efficacy of paxlovid on reducing mortality of COVID-19 patients in clinical setting, especially whether paxlovid modifies the risk of death in these severe and critical patients.

METHODS

Our retrospective cohort study was conducted on the medical records of patients, consecutively admitted for COVID-19 to five hospitals in Chongqing, China from Dec 8, 2022 to Jan 20, 2023. Based on whether patients received paxlovid during their hospitalization, patients were grouped as paxlovid group and non-paxlovid group. We used 1:1 ratio propensity score matching (PSM) in our study to adjust for confounding factors and differences between groups. Statistical analysis were performed by SPSS 23.0. The differences in 28-day mortality between these two groups and its influencing factors were the main results we focused on.

RESULTS

There were 1018 patients included in our study cohort. With 1:1 ratio PSM, each of the paxlovid group and non-paxlovid group included 237 patients. The results showed that patients using paxlovid have a lower 28-day mortality in overall population either before PSM (OR 0.594, 95% CI 0.385-0.917, p = 0.019) or after PSM (OR 0.458, 95% CI 0.272-0.774, p = 0.003) with multivariable adjusted logistic regression models. Meanwhile, in severe subgroup, it showed similar findings.With paxlovid treatment, it showed a significantly lower 28-day mortality in severe subgroup both before PSM (28% vs.41%, p = 0.008) and after PSM (19% vs.32%, p = 0.007).

CONCLUSION

Paxlovid can significantly reduce the risk of 28-day mortality in overall population and severe subgroup patients.This study distinguished the severe subgroup patients with COVID-19 who benefit more from paxlovid treatment.

Cytokine Storm in COVID-19: Insight into Pathological Mechanisms and Therapeutic Benefits of Chinese Herbal Medicines

Cytokine storm (CS) is the main driver of SARS-CoV-2-induced acute respiratory distress syndrome (ARDS) in severe coronavirus disease-19 (COVID-19). The pathological mechanisms of CS are quite complex and involve multiple critical molecular targets that turn self-limited and mild COVID-19 into a severe and life-threatening concern. At present, vaccines are strongly recommended as safe and effective treatments for preventing serious illness or death from COVID-19. However, effective treatment options are still lacking for people who are at the most risk or hospitalized with severe disease. Chinese herbal medicines have been shown to improve the clinical outcomes of mild to severe COVID-19 as an adjunct therapy, particular preventing the development of mild to severe ARDS. This review illustrates in detail the pathogenesis of CS-involved ARDS and its associated key molecular targets, cytokines and signalling pathways. The therapeutic targets were identified particularly in relation to the turning points of the development of COVID-19, from mild symptoms to severe ARDS. Preclinical and clinical studies were reviewed for the effects of Chinese herbal medicines together with conventional therapies in reducing ARDS symptoms and addressing critical therapeutic targets associated with CS. Multiple herbal formulations, herbal extracts and single bioactive phytochemicals with or without conventional therapies demonstrated strong anti-CS effects through multiple mechanisms. However, evidence from larger, well-designed clinical trials is lacking and their detailed mechanisms of action are yet to be well elucidated. More research is warranted to further evaluate the therapeutic value of Chinese herbal medicine for CS in COVID-19-induced ARDS.

Oral Bioavailability, Tissue Distribution, Metabolism, and Excretion of Panduratin A from Boesenbergia rotunda Extract in Healthy Rats

Background

Our previous studies in vitro and in vivo have shown anti-severe acute respiratory syndrome coronavirus 2 activity of fingerroot extract (Boesenbergia rotunda) and its phytochemical panduratin A.

Aim of Study

Therefore, the objective of this study was to determine the pharmacokinetic profiles of panduratin A, as a pure compound and in fingerroot extract, in rats.

Materials and Methods

Male rats were randomly divided into four groups. Rats underwent intravenous administration of 4.5 mg/kg panduratin A, a single oral administration of 45 mg/kg panduratin A, or a multiple oral administration of 45 mg/kg panduratin A-consisted fingerroot extract for 7 consecutive days. The concentrations of panduratin A in plasma, tissues, and excreta were measured by using LCMS with a validated method.

Results

The rats showed no change in health status after receiving all test preparations. The absolute oral bioavailability of panduratin A administered as pure panduratin A and fingerroot extract were approximately 9% and 6%, respectively. The peak concentrations for the single oral doses of 45 mg/kg panduratin A and fingerroot extract, were 4833 ± 659 and 3269 ± 819 µg/L, respectively. Panduratin A was mostly distributed in gastrointestinal organs, with the highest tissue-to-plasma ratio in the stomach. Approximately 20-30% of unchanged panduratin A from the administered dose was detected in feces while a negligible amount was found in urine. The major metabolites of administered panduratin A were identified in feces as oxidation and dioxidation products.

Conclusion

Panduratin A from fingerroot extract showed low oral bioavailability, good tissue distribution, and partially biotransformed before excretion via feces. These findings will assist in developing fingerroot extract as a phytopharmaceutical product for COVID-19 treatment.

Inhibitors of SARS-CoV-2 Main Protease (Mpro) as Anti-Coronavirus Agents

The main protease (Mpro) of SARS-CoV-2 is an essential enzyme that plays a critical part in the virus's life cycle, making it a significant target for developing antiviral drugs. The inhibition of SARS-CoV-2 Mpro has emerged as a promising approach for developing therapeutic agents to treat COVID-19. This review explores the structure of the Mpro protein and analyzes the progress made in understanding protein-ligand interactions of Mpro inhibitors. It focuses on binding kinetics, origin, and the chemical structure of these inhibitors. The review provides an in-depth analysis of recent clinical trials involving covalent and non-covalent inhibitors and emerging dual inhibitors targeting SARS-CoV-2 Mpro. By integrating findings from the literature and ongoing clinical trials, this review captures the current state of research into Mpro inhibitors, offering a comprehensive understanding of challenges and directions in their future development as anti-coronavirus agents. This information provides new insights and inspiration for medicinal chemists, paving the way for developing more effective Mpro inhibitors as novel COVID-19 therapies.

Effectiveness of azvudine against severe outcomes among hospitalized COVID-19 patients in Xinjiang, China: a single-center, retrospective, matched cohort study

BACKGROUND

Since the end of 2022, Azvudine was widely used to treat hospitalized coronavirus disease 2019 (COVID-19) patients in China. However, data on the real-world effectiveness of Azvudine against severe outcomes and post-COVID-19-conditions (PCC) among patients infected by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron variants was limited. This study evaluates the effectiveness of Azvudine in hospitalized COVID-19 patients during a SARS-CoV-2 Omicron BA.5 dominance period.

METHODS

From 1 November 2022 to 1 July 2023, an SARS-CoV-2 Omicron BA.5 dominant period, we conducted a single-center retrospective cohort study based on hospitalized patients with laboratory-confirmed SARS-CoV-2 infection from a tertiary hospital in Shihezi, China. Patients treated with Azvudine and usual care were propensity-score matched (PSM) at a 1:1 ratio to a control group in which patients received usual care only, with matching based on covariates such as sex, age, ethnicity, number of preexisting conditions, antibiotic use at admission, and baseline complete blood cell count. The primary outcomes were all-cause death and short-term (60 days) PCC post discharge. The secondary outcomes included the initiation of invasive mechanical ventilation and PCC at long-term post discharge (120 days). Cox proportional hazards (PH) regression models were employed to estimate the hazard ratios (HR) of Azvudine treatment for both all-cause death and invasive mechanical ventilation, and logistic regression models were used to estimate the odds ratios (OR) for short-term and long-term PCC. Subgroup analyses were performed based on a part of the matched covariates.

RESULTS

A total of 2,639 hospitalized patients with SARS-CoV-2 infection were initially identified, and 2,069 ineligible subjects were excluded from analyses. After matching, 297 Azvudine recipients and 297 matched controls were eligible for analyses. The incidence rate of all-cause death was relatively lower in the Azvudine group than in control group (0.007 per person, 95% confidence interval [CI]: 0.001, 0.024 vs 0.128, 95% CI: 0.092, 0.171), and the use of Azvudine was associated with a significantly lower risk of death (HR: 0.049, 95% CI: 0.012, 0.205). Subgroup analyses suggested protection of Azvudine against the risks of all-cause death among men, age over 65, patients without the preexisting conditions, and patients with antibiotics dispensed at admission. Statistical differences were not observed between the Azvudine group and the control group for the risks of invasive mechanical ventilation or short and long-term PCC.

CONCLUSIONS

Our findings indicated that Azvudine was associated with lower risk of all-cause death among hospitalized patients with Omicron BA.5 infection in a real-world setting. Further investigation is needed to explore the effectiveness of Azvudine against the PCC after discharge.

Clinico-Virological Outcomes and Mutational Profile of SARS-CoV-2 in Adults Treated with Ribavirin Aerosol for COVID-19 Pneumonia

The emergence of new SARS-CoV-2 variants can affect vaccine efficacy, laboratory diagnosis and the therapies already available, triggering interest in the search for antiviral agents for SARS-CoV-2 infections. Ribavirin (RBV) is a broad-spectrum antiviral with demonstrated in vitro activity against multiple viruses, including SARS-CoV-2. This retrospective study evaluated the dynamics and viral clearance of SARS-CoV-2 in hospitalised adult participants (PTs) with COVID-19 pneumonia who received an RBV aerosol within a compassionate use study. The impact of RBV on the clinical outcome and the mutational profile of SARS-CoV-2 was also assessed. The median RNA values measured in nine PTs included in this study decreased from baseline to discharge (at BL, threshold cycle (Ct) = 22.4, IQR 19.84-5.07; at discharge, Ct = 27.92, IQR 26.43-36.11), with a significant decline in the Ct value evaluated by Friedman rank ANOVA analysis, p = 0.032. Seven out of nine PTs experienced a clinical improvement, while two PTs deceased during hospitalisation. In PTs with a favourable outcome, the virus clearance rate at discharge was 28.6%. The cumulative clearance rate was 71.4% within 14 days from discharge. A mutational pattern after RBV was detected in three out of five PTs in whom whole-genome sequencing was available. Our findings suggest that RBV limits SARS-CoV-2 replication, possibly resulting in a favourable clinical outcome. Ribavirin may also contribute to the mutational spectrum of SARS-CoV-2.

Azvudine for the Treatment of COVID-19 in Pre-Existing Cardiovascular Diseases: A Single-Center, Real-World Experience

COVID-19 can lead to adverse outcomes in patients with pre-existing diseases. Azvudine has been approved for treating COVID-19 in China, but the real-world data is limited. It is aimed to investigate the efficacy of Azvudine in patients with COVID-19 and pre-existing cardiovascular diseases. Patients with confirmed COVID-19 and pre-existing cardiovascular diseases are retrospectively enrolled. The primary outcome is all-cause death during hospitalization. Overall, 351 patients are included, with a median age of 74 years, and 44% are female. 212 (60.6%) patients are severe cases. Azvudine is used in 106 (30.2%) patients and not in 245 (69.8%). 72 patients died during hospitalization. After multivariate adjustment, patients who received Azvudine a lower risk of all-cause death (hazard ratio: 0.431; 95% confidence interval: 0.252-0.738; p = 0.002) than controls. Azvudine therapy is also associated with lower risks of shock and acute kidney injury. For sensitivity analysis in the propensity score-matched cohort (n = 90 for each group), there is also a significant difference in all-cause death between the two groups (hazard ratio: 0.189; 95% confidence interval: 0.071-0.498; p < 0.001). This study indicated that Azvudine therapy is associated with better outcomes in COVID-19 patients with pre-existing cardiovascular diseases.

Safety and efficacy of Paxlovid in the treatment of adults with mild to moderate COVID-19 during the omicron epidemic: a multicentre study from China

BACKGROUND

Since December 2022, the Omicron variant has led to a widespread pandemic in China. The study was to explore the safety and effectiveness of Paxlovid for the treatment of coronavirus disease 2019 (COVID-19).

RESEARCH DESIGN AND METHODS

We included patients at risk of developing severe COVID-19, all of whom exhibited mild to moderate symptoms and were admitted to three hospital centers. Patients were divided into two groups: one received Paxlovid alongside standard care, while the other was given only standard care. We compared clinical characteristics, hospital stay duration, and clinical outcomes between two groups. Multi-factor analysis determined the independent risk factors influencing the duration of hospitalization and disease progression.

RESULTS

In the study, those treated with Paxlovid shorter hospital stays than those in the control group (p < 0.001). Multivariate analysis indicated that the absence of Paxlovid treatment was a distinct risk factor for hospitalizations lasting over 7 days (OR: 4.983, 95% CI: 3.828-6.486, p < 0.001) and 14 days (OR: 2.940, 95% CI: 2.402-3.597, p < 0.001).

CONCLUSION

Amid the Omicron outbreak, Paxlovid has proven to be a safe and effective treatment for reducing hospitalization durations for patients with mild to moderate COVID-19.

Natural-product-based, carrier-free, noncovalent nanoparticles for tumor chemo-photodynamic combination therapy

Cancer, with its diversity, heterogeneity, and complexity, is a significant contributor to global morbidity, disability, and mortality, highlighting the necessity for transformative treatment approaches. Photodynamic therapy (PDT) has aroused continuous interest as a viable alternative to conventional cancer treatments that encounter drug resistance. Nanotechnology has brought new advances in medicine and has shown great potential in drug delivery and cancer treatment. For precise and efficient therapeutic utilization of such a tumor therapeutic approach with high spatiotemporal selectivity and minimal invasiveness, the carrier-free noncovalent nanoparticles (NPs) based on chemo-photodynamic combination therapy is essential. Utilizing natural products as the foundation for nanodrug development offers unparalleled advantages, including exceptional pharmacological activity, easy functionalization/modification, and well biocompatibility. The natural-product-based, carrier-free, noncovalent NPs revealed excellent synergistic anticancer activity in comparison with free photosensitizers and free bioactive natural products, representing an alternative and favorable combination therapeutic avenue to improve therapeutic efficacy. Herein, a comprehensive summary of current strategies and representative application examples of carrier-free noncovalent NPs in the past decade based on natural products (such as paclitaxel, 10-hydroxycamptothecin, doxorubicin, etoposide, combretastatin A4, epigallocatechin gallate, and curcumin) for tumor chemo-photodynamic combination therapy. We highlight the insightful design and synthesis of the smart carrier-free NPs that aim to enhance PDT efficacy. Meanwhile, we discuss the future challenges and potential opportunities associated with these NPs to provide new enlightenment, spur innovative ideas, and facilitate PDT-mediated clinical transformation.

Modulation in serum and hematological parameters as a prognostic indicator of COVID-19 infection in hypertension, diabetes mellitus, and different cardiovascular diseases

SARS-CoV-2 infection affects and modulates serum as well as hematological parameters. However, whether it modifies these parameters in the existing disease conditions, which help in the erection of specific treatments for the disease, is under investigation. Here, we aimed to determine whether serum and hematological parameters alteration in various diseases, diabetes mellitus (DM), hypertension (HTN), ischemic heart disease (IHD) and myocardial infarction (MI) conditions correlate and signal SARS-CoV-2 infection, which could be used as a rapid diagnosis tool for SARS-CoV-2 infection in disease conditions. To assess the projected goals, we collected blood samples of 1,113 male and female patients with solo and multiple disease conditions of DM/HTN/IHD/MI with severe COVID-19, followed by biochemical analysis, including COVID-19 virus detection by RT-qPCR. Furthermore, blood was collected from age-matched disease and healthy individuals 502 and 660 and considered as negative control. In our results, we examined higher levels of serum parameters, including D-dimer, ferritin, hs-CRP, and LDH, as well as hematological parameters, including TLC in sole and multiple diseases (DM/HTN/IHD/MI) conditions compared to the control subjects. Besides, the hematological parameters, including Hb, RBC, and platelet levels, decreased in the patients. In addition, we found declined levels of leukocyte count (%), lymphocyte (%), monocyte (%), and eosinophil (%), and elevated level of neutrophil levels (%) in all the disease patients infected with SARS-CoV-2. Besides, NLR and NMR ratios were also statistically significantly (p < 0.05) high in the patients with solo and multiple disease conditions of DM/HTN/IHD/MI infected with the SARS-CoV-2 virus. In conclusion, rapid alteration of sera and hematological parameters are associated with SARS-CoV-2 infections, which could help signal COVID-19 in respective disease patients. Moreover, our results may help to improve the clinical management for the rapid diagnosis of COVID-19 concurrent with respective diseases.

Redox Biomarkers - An Effective Tool for Diagnosing COVID-19 Patients and Convalescents

Aim

COVID-19 triggers the overproduction of reactive oxygen species (ROS) which, in combination with a weakened antioxidant barrier, can lead to protein oxidation and lipid peroxidation. The aim of this study was to evaluate enzymatic and non-enzymatic antioxidants, the overall redox potential, and protein and lipid peroxidation products in COVID-19 patients, convalescents, and healthy subjects, and to the determine the diagnostic applicability of these parameters in COVID-19 patients.

Materials and Methods

The study involved 218 patients with COVID-19, 69 convalescents, and 48 healthy subjects who were selected for the research based on age and sex. The study was conducted between 20 February 2021 and 20 November 2021 in Białystok, Poland. The antioxidant barrier, redox status, and oxidative damage products were assessed in serum/plasma samples with the use of colorimetric and spectrophotometric assays.

Results

Glutathione reductase (GR) activity was higher, whereas total antioxidant capacity (TAC) was lower in COVID-19 patients than in convalescents (p<0.0001) and the control group (p<0.0001). The concentrations of advanced glycation end products (AGEs), advanced oxidation protein products (AOPP), 4-hydroxynonenal (4-HNE), and malondialdehyde (MDA) were higher in COVID-19 patients (p<0.0001) and convalescents (p<0.0001) than in the control group. AGEs were the most effective diagnostic biomarker for differentiating COVID-19 patients from the control group (AUC=0.9971) and convalescents from the control group (AUC=1.000).

Conclusion

An infection with the SARS-CoV-2 disrupts the redox balance and increases protein oxidation and lipid peroxidation. AGEs fulfill the criteria for a potential diagnostic biomarker in COVID-19 patients and convalescents.

Anti-SARS-CoV-2 glyco-humanized polyclonal antibody XAV-19: phase II/III randomized placebo-controlled trial shows acceleration to recovery for mild to moderate patients with COVID-19

Introduction

XAV-19 is a glyco-humanized swine polyclonal antibody targeting SARS-CoV-2 with high neutralizing activity. The safety and clinical efficacy of XAV-19 were investigated in patients with mild to moderate COVID-19.

Methods

This phase II/III, multicentric, randomized, double-blind, placebo-controlled clinical trial was conducted to evaluate the safety and clinical efficacy of XAV-19 in patients with a seven-point WHO score of 2 to 4 at randomization, i.e., inpatients with COVID-19 requiring or not requiring low-flow oxygen therapy, and outpatients not requiring oxygen (EUROXAV trial, NCT04928430). Adult patients presenting in specialized or emergency units with confirmed COVID-19 and giving their consent to participate in the study were randomized to receive 150 mg of XAV-19 or placebo. The primary endpoint was the proportion of patients with aggravation within 8 days after treatment, defined as a worsening of the seven-point WHO score of at least one point between day 8 and day 1 (inclusion). The neutralization activity of XAV-19 against variants circulating during the trial was tested in parallel.

Results

From March 2021 to October 2022, 279 patients received either XAV-19 (N = 140) or placebo (N = 139). A slow enrollment and a low rate of events forced the termination of the premature trial. XAV-19 was well tolerated. Underpowered statistics did not allow the detection of any difference in the primary endpoint between the two groups or in stratified groups. Interestingly, analysis of the time to improvement (secondary endpoint) showed that XAV-19 significantly accelerated the recovery for patients with a WHO score of 2 or 3 (median at 7 days vs. 14 days, p = 0.0159), and even more for patients with a WHO score of 2 (4 days vs. 14 days, p = 0.0003). The neutralizing activity against Omicron and BA.2, BA.2.12.1, BA.4/5, and BQ.1.1 subvariants was shown.

Discussion

In this randomized placebo- controlled trial with premature termination, reduction of aggravation by XAV-19 at day 8 in patients with COVID-19 was not detectable. However, a significant reduction of the time to improvement for patients not requiring oxygen was observed. XAV-19 maintained a neutralizing activity against SARS-CoV-2 variants. Altogether, these data support a possible therapeutic interest for patients with mild to moderate COVID-19 requiring anti-SARS-CoV-2 neutralizing antibodies.

Clinical Trial Registration

https://clinicaltrials.gov/, identifier NCT04928430; https://www.clinicaltrialsregister.eu/about.html (EudraCT), identifier 2020-005979-12.

Self-managing symptoms of Long COVID: an education and strategies research protocol

Post-acute sequelae of SARS-COV-2 (PASC) is growing in prevalence, and involves symptoms originating from the central neurological, cardiovascular, respiratory, gastrointestinal, autonomic nervous, or immune systems. There are non-specific symptoms such as fatigue, headaches, and brain fog, which cannot be ascribed to a single system. PASC places a notable strain on our healthcare system, which is already laden with a large number of acute-COVID-19 patients. Furthermore, it impedes social, academic and vocational functioning, and impacts family life, relationships, and work/financial life. The treatment for PASC needs to target this non-specific etiology and wide-ranging sequelae. In conditions similar to PASC, such as "chemo brain," and prolonged symptoms of concussion, the non-specific symptoms have shown to be effectively managed through education and strategies for self-management and Mindfulness interventions. However, such interventions have yet to be empirically evaluated in PASC to our knowledge. In response to this gap, we have developed a virtual education intervention synthesized by psychiatrists and clinical psychologists for the current study. We will undertake a two-phase randomized controlled trial to determine the feasibility (Phase 1; N = 90) and efficacy (Phase 2; sample sized based on phase 1 results) of the novel 8 week Education and Self-Management Strategies group compared to a mindfulness skills program, both delivered virtually. Main outcomes include confidence/ability to self-manage symptoms, quality of life, and healthcare utilization. This study stands to mitigate the deleterious intrusiveness of symptoms on everyday life in patients with PASC, and may also help to reduce the impact of PASC on the healthcare system. Clinical trial registration:https://classic.clinicaltrials.gov/ct2/show/NCT05268523; identifier NCT05268523.

The potential of some functional group compounds substituted 8-Manzamine A as RSK1 inhibitors: molecular docking and molecular dynamics simulations

Cancer, an incurable global disease, demands urgent anti-cancer drug development. Marine alkaloids like Manzamine and its derivatives show promise as RSK inhibitors against cancer cell invasion. Replacing the hydrogen at the 8-position of Manzamine A with a hydroxyl group has been shown to significantly enhance its biological activity. In this article, we designed various functional group compounds (A1-A21) substituted 8-Manzamine A by docking, MM-GBSA, molecular dynamics (MD) simulation, and well-tempered metadynamics (WT-MetaD) simulations to evaluate their potential as RSK1 inhibitors. Ligands A1-A21 were docked in the RSK1 N-terminal kinase domain (PDB ID: 2Z7Q) using the Glide module. The calculation of binding energy was performed using Prime MM-GB/SA, while MD simulations were conducted with the Desmond module of Schrodinger suite 2023. Compound A5 exhibits the highest G-score (-7.01) compared to 8-Hydroxymanzamine A (-6.08). Additionally, compounds A6, A10, A12, A17, A11, A4, and A13 demonstrate increased activity against RSK1 when compared to both 8-Hydroxymanzamine A and Manzamine A. Residues LEU68, VAL76, LEU141, PHE143, LEU144, PHE150, ASP148, GLU191, and LEU194 of RSK1 protein play a key role in binding with ligands. An MD simulation of Compound A5 was carried out to explore the dynamic interactions within the protein-ligand complex. Furthermore, WT-MetaD simulations validated the docking study results and identified the most energetically favored conformations for the A5/RSK1 complex. Ligands A5, A6, A10, A12, A17, A11, A4, and A13, featuring diverse functional groups and good Glide scores, may have the potential for significant RSK1 activity and merit further development.

An ensemble docking-based virtual screening and molecular dynamics simulation of phytochemical compounds from Malaysian Kelulut Honey (KH) against SARS-CoV-2 target enzyme, human angiotensin-converting enzyme 2 (ACE-2)

The human angiotensin-converting enzyme 2 (ACE-2) receptor is a metalloenzyme that plays an important role in regulating blood pressure by modulating angiotensin II. This receptor facilitates SARS-CoV-2 entry into human cells via receptor-mediated endocytosis, causing the global COVID-19 pandemic and a major health crisis. Kelulut honey (KH), one of Malaysian honey recently gained attention for its distinct flavour and taste while having many nutritional and medicinal properties. Recent study demonstrates the antiviral potential of KH against SARS-CoV-2 by inhibiting ACE-2 in vitro, but the bioactive compound pertaining to the ACE-2 inhibition is yet unknown. An ensemble docking-based virtual screening was employed to screen the phytochemical compounds from KH with high binding affinity against the 10 best representative structures of ACE-2 that mostly formed from MD simulation. From 110 phytochemicals previously identified in KH, 27 compounds passed the ADMET analysis and proceeded to docking. Among the docked compound, SDC and FMN consistently exhibited strong binding to ACE-2's active site (-9.719 and -9.473 kcal/mol) and allosteric site (-7.305 and -7.464 kcal/mol) as compared to potent ACE-2 inhibitor, MLN 4760. Detailed trajectory analysis of MD simulation showed stable binding interaction towards active and allosteric sites of ACE-2. KH's compounds show promise in inhibiting SARS-CoV-2 binding to ACE-2 receptors, indicating potential for preventive use or as a supplement to other COVID-19 treatments. Additional research is needed to confirm KH's antiviral effects and its role in SARS-CoV-2 therapy, including prophylaxis and adjuvant treatment with vaccination.

On the origins of SARS-CoV-2 main protease inhibitors

In order to address the world-wide health challenge caused by the COVID-19 pandemic, the 3CL protease/SARS-CoV-2 main protease (SARS-CoV-2-Mpro) coded by its nsp5 gene became one of the biochemical targets for the design of antiviral drugs. In less than 3 years of research, 4 inhibitors of SARS-CoV-2-Mpro have actually been authorized for COVID-19 treatment (nirmatrelvir, ensitrelvir, leritrelvir and simnotrelvir) and more such as EDP-235, FB-2001 and STI-1558/Olgotrelvir or five undisclosed compounds (CDI-988, ASC11, ALG-097558, QLS1128 and H-10517) are undergoing clinical trials. This review is an attempt to picture this quite unprecedented medicinal chemistry feat and provide insights on how these cysteine protease inhibitors were discovered. Since many series of covalent SARS-CoV-2-Mpro inhibitors owe some of their origins to previous work on other proteases, we first provided a description of various inhibitors of cysteine-bearing human caspase-1 or cathepsin K, as well as inhibitors of serine proteases such as human dipeptidyl peptidase-4 or the hepatitis C protein complex NS3/4A. This is then followed by a description of the results of the approaches adopted (repurposing, structure-based and high throughput screening) to discover coronavirus main protease inhibitors.

Myocardial Oedema as a Consequence of Viral Infection and Persistence-A Narrative Review with Focus on COVID-19 and Post COVID Sequelae

Microvascular integrity is a critical factor in myocardial fluid homeostasis. The subtle equilibrium between capillary filtration and lymphatic fluid removal is disturbed during pathological processes leading to inflammation, but also in hypoxia or due to alterations in vascular perfusion and coagulability. The degradation of the glycocalyx as the main component of the endothelial filtration barrier as well as pericyte disintegration results in the accumulation of interstitial and intracellular water. Moreover, lymphatic dysfunction evokes an increase in metabolic waste products, cytokines and inflammatory cells in the interstitial space contributing to myocardial oedema formation. This leads to myocardial stiffness and impaired contractility, eventually resulting in cardiomyocyte apoptosis, myocardial remodelling and fibrosis. The following article reviews pathophysiological inflammatory processes leading to myocardial oedema including myocarditis, ischaemia-reperfusion injury and viral infections with a special focus on the pathomechanisms evoked by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. In addition, clinical implications including potential long-term effects due to viral persistence (long COVID), as well as treatment options, are discussed.

Real-World Effectiveness Study of Nirmatrelvir-Ritonavir or Molnupiravir in Hospitalized Unvaccinated Patients with Chronic Respiratory Diseases and Moderate COVID-19 at Presentation

Introduction

Nirmatrelvir-ritonavir (NMV-r) and molnupiravir (MOL) were developed as out-patient anti-viral for mild COVID-19. There was limited data on their role in treating COVID-19 for hospitalized patients, especially among adult patients who are unvaccinated and had chronic respiratory diseases.

Methods

A territory-wide retrospective study was conducted in Hong Kong to compare the efficacy of NMV-r and MOL against COVID-19 in unvaccinated adult patients with asthma, chronic obstructive pulmonary disease, bronchiectasis and interstitial lung diseases presenting with moderate COVID-19 from 16th February 2022 to 15th March 2023.

Results

A total of 1354 patients were included, 738 received NMV-r and 616 received MOL. NMV-r was more effective in reducing 90-day mortality with adjusted hazard ratios (aHR) of 0.508 (95% confidence interval [CI] = 0.314-0.822, p = 0.006). Patients who received NMV-r also had significantly shorter length of stay (LOS) than those receiving MOL, with median LOS of 4 (Interquartile range [IQR] = 2-7) for NMV-r and 6 (IQR = 3-10) for MOL (p-value < 0.001). There was no statistically significant difference in the development of respiratory failure and severe respiratory failure in the two groups.

Discussion

NMV-r was more effective than MOL among unvaccinated adults with chronic respiratory diseases who were hospitalized for moderate COVID-19 without hypoxaemia on admission.

The Functional Roles of MDSCs in Severe COVID-19 Pathogenesis

Severe COVID-19 is a major cause of morbidity and mortality worldwide, especially among those with co-morbidities, the elderly, and the immunocompromised. However, the molecular determinants critical for severe COVID-19 progression remain to be fully elucidated. Meta-analyses of transcriptomic RNAseq and single-cell sequencing datasets comparing severe and mild COVID-19 patients have demonstrated that the early expansion of myeloid-derived suppressor cells (MDSCs) could be a key feature of severe COVID-19 progression. Besides serving as potential early prognostic biomarkers for severe COVID-19 progression, several studies have also indicated the functional roles of MDSCs in severe COVID-19 pathogenesis and possibly even long COVID. Given the potential links between MDSCs and severe COVID-19, we examine the existing literature summarizing the characteristics of MDSCs, provide evidence of MDSCs in facilitating severe COVID-19 pathogenesis, and discuss the potential therapeutic avenues that can be explored to reduce the risk and burden of severe COVID-19. We also provide a web app where users can visualize the temporal changes in specific genes or MDSC-related gene sets during severe COVID-19 progression and disease resolution, based on our previous study.

Strategies for the development and approval of COVID-19 vaccines and therapeutics in the post-pandemic period

The spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has resulted in significant casualties and put immense strain on public health systems worldwide, leading to economic recession and social unrest. In response, various prevention and control strategies have been implemented globally, including vaccine and drug development and the promotion of preventive measures. Implementing these strategies has effectively curbed the transmission of the virus, reduced infection rates, and gradually restored normal social and economic activities. However, the mutations of SARS-CoV-2 have led to inevitable infections and reinfections, and the number of deaths continues to rise. Therefore, there is still a need to improve existing prevention and control strategies, mainly focusing on developing novel vaccines and drugs, expediting medical authorization processes, and keeping epidemic surveillance. These measures are crucial to combat the Coronavirus disease (COVID-19) pandemic and achieve sustained, long-term prevention, management, and disease control. Here, we summarized the characteristics of existing COVID-19 vaccines and drugs and suggested potential future directions for their development. Furthermore, we discussed the COVID-19-related policies implemented over the past years and presented some strategies for the future.

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.

Pathogen evolution, prevention/control strategy and clinical features of COVID-19: experiences from China

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was reported at the end of 2019 as a worldwide health concern causing a pandemic of unusual viral pneumonia and many other organ damages, which was defined by the World Health Organization as coronavirus disease 2019 (COVID-19). The pandemic is considered a significant threat to global public health till now. In this review, we have summarized the lessons learnt during the emergence and spread of SARS-CoV-2, including its prototype and variants. The overall clinical features of variants of concern (VOC), heterogeneity in the clinical manifestations, radiology and pathology of COVID-19 patients are also discussed, along with advances in therapeutic agents.

SARS-CoV-2 Aerosol and Intranasal Exposure Models in Ferrets

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the causative agent of the worldwide COVID-19 pandemic. Animal models are extremely helpful for testing vaccines and therapeutics and for dissecting the viral and host factors that contribute to disease severity and transmissibility. Here, we report the assessment and comparison of intranasal and small particle (~3 µm) aerosol SARS-CoV-2 exposure in ferrets. The primary endpoints for analysis were clinical signs of disease, recovery of the virus in the upper respiratory tract, and the severity of damage within the respiratory tract. This work demonstrated that ferrets were productively infected with SARS-CoV-2 following either intranasal or small particle aerosol exposure. SARS-CoV-2 infection of ferrets resulted in an asymptomatic disease course following either intranasal or small particle aerosol exposure, with no clinical signs, significant weight loss, or fever. In both aerosol and intranasal ferret models, SARS-CoV-2 replication, viral genomes, and viral antigens were detected within the upper respiratory tract, with little to no viral material detected in the lungs. The ferrets exhibited a specific IgG immune response to the SARS-CoV-2 full spike protein. Mild pathological findings included inflammation, necrosis, and edema within nasal turbinates, which correlated to positive immunohistochemical staining for the SARS-CoV-2 virus. Environmental sampling was performed following intranasal exposure of ferrets, and SARS-CoV-2 genomic material was detected on the feeders and nesting areas from days 2-10 post-exposure. We conclude that both intranasal and small particle aerosol ferret models displayed measurable parameters that could be utilized for future studies, including transmission studies and testing SARS-CoV-2 vaccines and therapeutics.

Efficacy and Safety of Remdesivir in Hospitalized Pediatric COVID-19: A Retrospective Case-Controlled Study

Introduction

While most children experience mild coronavirus disease 2019 (COVID-19) infections, a minority of cases progress to severe or critical illness. This study aimed to assess the efficacy and safety of Remdesivir (RDV) therapy in children with moderate to severe COVID-19, enhancing clinical decision-making and expanding our understanding of antiviral treatments for pediatric patients.

Methods

The study included 60 patients, 38 receiving RDV treatment and 22 serving as the control group. Data was collected retrospectively from January 2021 to January 2022 through electronic hospital records.

Results

Regarding the main clinical symptoms reported, most patients experienced Upper Respiratory Tract Infections (93.3%), indicating respiratory involvement. Additional symptoms included Central Nervous System (11.7%) and Gastrointestinal (10.0%). Among the 38 cases in the RDV group included in the study, the adverse effects associated with using RDV: Hypoalbuminemia in 19 cases (50.0%) and anemia in 18 cases (47.4%), making them the most common adverse effects. Only one case in the RDV group experienced non-RDV-related death with a different clinical diagnosis. The results showed that RDV treatment was well-tolerated in pediatric patients, with no significant differences in hospital stay and oxygen treatment compared to the control group with P values (0.2, 0.18), respectively.

Conclusion

The outcomes indicate that Remdesivir may represent a safe and therapeutic choice for children with coronavirus disease 2019 (COVID-19).

Anti-viral effect of usenamine a using SARS-CoV-2 pseudo-typed viruses

The escalating pandemic brought about by the novel SARS-CoV-2 virus is threatening global health, and thus, it is necessary to develop effective antiviral drugs. Usenamine A is a dibenzo-furan derivative separated from lichen Usnea diffracta showing broad-spectrum activity against different viruses. We evaluate that usenamine A has antiviral effects against novel SARS-CoV-2 Delta variant pseudotyped viruses (PVs) in A549 cells. In addition, usenamine A significantly suppresses SARS-CoV-2 PV-induced mitochondrial depolarization, elevated reactive oxygen species (ROS) levels, apoptosis, and inflammation. Usenamine A also causes the SARS-CoV-2 spike protein to become less stable. Thus, usenamine A shows potential as an antiviral drug that can provide protection against COVID-19.

Inflammatory predictors (eosinophil, C-RP and IL-6) and effectiveness of oral Azvudine tablets treatment in COVID-19 hospitalized patients: A retrospective, self-controlled study

Background

Although vaccinations and antiviral drugs are widely used in the clinical treatment worldwide, there is little investigation on the clinical outcomes and effectiveness of oral Azvudine tablets (FNC) treatment in COVID-19 hospitalized patients. The previous data showed Azvudine treatment was closely related to reduced virus shedding time, but the potential role of Azvudine on inflammatory response is scarce. Thus, this study is to investigate inflammatory predictors and effectiveness of oral Azvudine tablets treatment in COVID-19 hospitalized patients.

Methods

A total of 600 out of hospitalized patients were retrospectively collected over a 2-month period, of whom 60 out of hospitalized patients infected SARS-CoV-2. 32 of hospitalized patients who received Azvudine tablets were collected and the rest did not. Oral Azvudine tablets treatment: 5 mg/day for 7-14 days. We analyzed the routine blood tests, blood coagulation test, NT-proBNP, Troponin (cTNl), Creatine kinase MB (CK-MB) after oral Azvudine tablets treatment compared with that in before oral Azvudine tablets treatment. Also, we compared the CT chest and length of Stay after Azvudine treatment.

Results

We found that the number and percentage of eosinophil increased significantly, but the levels of C-reactive protein (C-RP) and IL-6 reduced remarkably after Azvudine treatment. In blood coagulation tests, the results showed that activated partial thromboplastin time (APTT) (mean ± SEM: 2.950 ± 2.268s) and fibrinogen (mean ± SEM: 0.8910 ± 0.5134g/L) downregulated slightly, while there was similar in the level of D-Dimer (mean ± SEM: 0.1660 ± 0.3108 μg/mL) before and after Azvudine treatment. The expression of NT-proBNP reduced in Azvudine treatment (mean ± SEM: 897.1 ± 557.1pg/mL). Chest computed tomography (CT) scan reports also demonstrated that Azvudine treatment improved lung symptoms in COVID-19 hospitalized patients. Moreover, there is no difference in the average of length of stay in Azvudine treatment (the average of LOS days: 9.0) and no treatment (the average of LOS days: 9.0).

Conclusion

Oral Azvudine tablets treatment was associated with decreased inflammatory response and improved blood coagulation function, which should be substantial clinical benefits in COVID-19 hospitalized patients.

Remdesivir or Nirmatrelvir/Ritonavir Therapy for Omicron SARS-CoV-2 Infection in Hematological Patients and Cell Therapy Recipients

BACKGROUND

Scarce data exist that analyze the outcomes of hematological patients with SARS-CoV-2 infection during the Omicron variant period who received treatment with remdesivir or nirmatrelvir/ritonavir.

METHODS

This study aims to address this issue by using a retrospective observational registry, created by the Spanish Hematopoietic Stem Cell Transplantation and Cell Therapy Group, spanning from 27 December 2021 to 30 April 2023.

RESULTS

This study included 466 patients, 243 (52%) who were treated with remdesivir and 223 (48%) with nirmatrelvir/ritonavir. Nirmatrelvir/ritonavir was primarily used for mild cases, resulting in a lower COVID-19-related mortality rate (1.3%), while remdesivir was preferred for moderate to severe cases (40%), exhibiting a higher mortality rate (9%). A multivariate analysis in the remdesivir cohort showed that male gender (odds ratio (OR) 0.35, p = 0.042) correlated with a lower mortality risk, while corticosteroid use (OR 9.4, p < 0.001) and co-infection (OR 2.8, p = 0.047) were linked to a higher mortality risk. Prolonged virus shedding was common, with 52% of patients shedding the virus for more than 25 days. In patients treated with remdesivir, factors associated with prolonged shedding included B-cell malignancy as well as underlying disease, severe disease, a later onset of and shorter duration of remdesivir treatment and a higher baseline viral load. Nirmatrelvir/ritonavir demonstrated a comparable safety profile to remdesivir, despite a higher risk of drug interactions.

CONCLUSIONS

Nirmatrelvir/ritonavir proved to be a safe and effective option for treating mild cases in the outpatient setting, while remdesivir was preferred for severe cases, where corticosteroids and co-infection significantly predicted worse outcomes. Despite antiviral therapy, prolonged shedding remains a matter of concern.

Substitutions in SARS-CoV-2 Mpro Selected by Protease Inhibitor Boceprevir Confer Resistance to Nirmatrelvir

Nirmatrelvir, which targets the SARS-CoV-2 main protease (Mpro), is the first-in-line drug for prevention and treatment of severe COVID-19, and additional Mpro inhibitors are in development. However, the risk of resistance development threatens the future efficacy of such direct-acting antivirals. To gain knowledge on viral correlates of resistance to Mpro inhibitors, we selected resistant SARS-CoV-2 under treatment with the nirmatrelvir-related protease inhibitor boceprevir. SARS-CoV-2 selected during five escape experiments in VeroE6 cells showed cross-resistance to nirmatrelvir with up to 7.3-fold increased half-maximal effective concentration compared to original SARS-CoV-2, determined in concentration-response experiments. Sequence analysis revealed that escape viruses harbored Mpro substitutions L50F and A173V. For reverse genetic studies, these substitutions were introduced into a cell-culture-infectious SARS-CoV-2 clone. Infectivity titration and analysis of genetic stability of cell-culture-derived engineered SARS-CoV-2 mutants showed that L50F rescued the fitness cost conferred by A173V. In the concentration-response experiments, A173V was the main driver of resistance to boceprevir and nirmatrelvir. Structural analysis of Mpro suggested that A173V can cause resistance by making boceprevir and nirmatrelvir binding less favorable. This study contributes to a comprehensive overview of the resistance profile of the first-in-line COVID-19 treatment nirmatrelvir and can thus inform population monitoring and contribute to pandemic preparedness.

Efficacy of Nirmatrelvir-Ritonavir versus Azvudine for COVID-19 Treatment in Tibet: A Retrospective Study

Background

Nirmatrelvir-ritonavir, also known as paxlovid, is a widely used antiviral drug against coronavirus disease 2019 (COVID-19). Azvudine, a drug previously used to treat human immunodeficiency virus-1, has also been used to treat COVID-19 in China. However, only a few clinical studies have evaluated the effects of azvudine. Additionally, studies comparing nirmatrelvir-ritonavir with azvudine have been limited in number.

Methods

We carried out a retrospective case‒control analysis at the Third People's Hospital of the Tibet Autonomous Region. Eighty-two eligible patients with COVID-19 who received azvudine treatment were included. A total of 145 control patients who received nirmatrelvir-ritonavir treatment were selected by propensity score matching for age, sex, the severity of disease, and initial cycle threshold values. A comparison of the nucleic acid test negative conversion time, the length of hospitalization, and mortality rate was conducted.

Results

Overall, the mean nucleic acid test negative conversion time was comparable between the nirmatrelvir-ritonavir and azvudine groups (7.0 [11.0, 15.0] vs 9.0 [6.0, 12.0] days, P=0.064). However, for patients with mild COVID-19, the nucleic acid test negative conversion time was significantly shorter in the nirmatrelvir-ritonavir group than in the azvudine group (6.0 [5.0, 8.0] vs 8.0 [6.0, 11.0] days, P=0.029). The nirmatrelvir-ritonavir group and the azvudine group did not differ significantly in length of hospitalization (8.0 [5.5,10.5] vs 8.0 [5.0,10.0] days, P=0.378). Regarding the mortality rate, there were 4 (2.8%) deaths in the nirmatrelvir-ritonavir group and 3 (3.7%) in the azvudine group (P=0.706).

Conclusion

Azvudine is generally as effective as nirmatrelvir-ritonavir, but for patients with mild COVID-19, nirmatrelvir-ritonavir could suppress the virus more rapidly. For those who cannot be treated with nirmatrelvir-ritonavir, azvudine might be an effective therapy for COVID-19.

An Overview on Anti-COVID-19 Drug Achievements and Challenges Ahead

The appearance of several coronavirus pandemics/epidemics during the last two decades (SARS-CoV-1 in 2002, MERS-CoV in 2012, and SARS-CoV-2 in 2019) indicates that humanity will face increasing challenges from coronaviruses in the future. The emergence of new strains with similar transmission characteristics as SARS-CoV-2 and mortality rates similar to SARS-CoV-1 (∼10% mortality) or MERS-CoV (∼35% mortality) in the future is a terrifying possibility. Therefore, getting enough preparations to face such risks is an inevitable necessity. The present study aims to review the drug achievements and challenges in the fight against SARS-CoV-2 with a combined perspective derived from pharmacology, pharmacotherapy, and medicinal chemistry insights. Appreciating all the efforts made during the past few years, there is strong evidence that the desired results have not yet been achieved and research in this area should still be pursued seriously. By expressing some pessimistic possibilities and concluding that the drug discovery and pharmacotherapy of COVID-19 have not been successful so far, this short essay tries to draw the attention of responsible authorities to be more prepared against future coronavirus epidemics/pandemics.

Stand Up to Stand Out: Natural Dietary Polyphenols Curcumin, Resveratrol, and Gossypol as Potential Therapeutic Candidates against Severe Acute Respiratory Syndrome Coronavirus 2 Infection

The COVID-19 pandemic has stimulated collaborative drug discovery efforts in academia and the industry with the aim of developing therapies and vaccines that target SARS-CoV-2. Several novel therapies have been approved and deployed in the last three years. However, their clinical application has revealed limitations due to the rapid emergence of viral variants. Therefore, the development of next-generation SARS-CoV-2 therapeutic agents with a high potency and safety profile remains a high priority for global health. Increasing awareness of the "back to nature" approach for improving human health has prompted renewed interest in natural products, especially dietary polyphenols, as an additional therapeutic strategy to treat SARS-CoV-2 patients, owing to its good safety profile, exceptional nutritional value, health-promoting benefits (including potential antiviral properties), affordability, and availability. Herein, we describe the biological properties and pleiotropic molecular mechanisms of dietary polyphenols curcumin, resveratrol, and gossypol as inhibitors against SARS-CoV-2 and its variants as observed in in vitro and in vivo studies. Based on the advantages and disadvantages of dietary polyphenols and to obtain maximal benefits, several strategies such as nanotechnology (e.g., curcumin-incorporated nanofibrous membranes with antibacterial-antiviral ability), lead optimization (e.g., a methylated analog of curcumin), combination therapies (e.g., a specific combination of plant extracts and micronutrients), and broad-spectrum activities (e.g., gossypol broadly inhibits coronaviruses) have also been emphasized as positive factors in the facilitation of anti-SARS-CoV-2 drug development to support effective long-term pandemic management and control.

Screening, Synthesis and Biochemical Characterization of SARS-CoV-2 Protease Inhibitors

The severe acute respiratory syndrome-causing coronavirus 2 (SARS-CoV-2) papain-like protease (PLpro) and main protease (Mpro) play an important role in viral replication events and are important targets for anti-coronavirus drug discovery. In search of these protease inhibitors, we screened a library of 1300 compounds using a fluorescence thermal shift assay (FTSA) and identified 53 hits that thermally stabilized or destabilized PLpro. The hit compounds structurally belonged to two classes of small molecules: thiazole derivatives and symmetrical disulfide compounds. Compound dissociation constants (Kd) were determined using an enzymatic inhibition method. Seven aromatic disulfide compounds were identified as efficient PLpro inhibitors with Kd values in the micromolar range. Two disulfides displayed six-fold higher potency for PLpro (Kd = 0.5 µM) than for Mpro. The disulfide derivatives bound covalently to both proteases, as confirmed through mass spectrometry. The identified compounds can serve as lead compounds for further chemical optimization toward anti-COVID-19 drugs.

Exploring the Network between Adipocytokines and Inflammatory Response in SARS-CoV-2 Infection: A Scoping Review

Adipose tissue is actually regarded as an endocrine organ, rather than as an organ that merely stores energy. During the COVID-19 pandemic, obesity has undoubtedly emerged as one of the most important risk factors for disease severity and poor outcomes related to SARS-CoV-2 infection. The aberrant production of cytokine-like hormones, called adipokines, may contribute to alterations in metabolism, dysfunction in vascular endothelium and the creation of a state of general chronic inflammation. Moreover, chronic, low-grade inflammation linked to obesity predisposes the host to immunosuppression and excessive cytokine activation. In this respect, understanding the mechanisms that link obesity with the severity of SARS-CoV-2 infection could represent a real game changer in the development of new therapeutic strategies. Our review therefore examines the pathogenic mechanisms of SARS-CoV-2, the implications with visceral adipose tissue and the influences of the adipose tissue and its adipokines on the clinical behavior of COVID-19.

Spray-Dried Inhalable Microparticles Combining Remdesivir and Ebselen against SARS-CoV-2 Infection

There is a continuous effort to develop efficient treatments for coronavirus disease 2019 (COVID-19) and other viral respiratory diseases. Among the different strategies, inhaled treatment is considered one of the most logical and efficient approaches to treating COVID-19, as the causative "SARS-CoV-2 virus RNA" predominantly infects the respiratory tract. COVID-19 treatments initially relied on repurposed drugs, with a few additional strategies developed during the last two years, and all of them are based on monotherapy. However, drug combinations have been found to be more effective than monotherapy in other viral diseases such as HIV, influenza, and hepatitis C virus. In the case of SARS-CoV-2 infection, in vitro studies have shown synergistic antiviral activity combining remdesivir with ebselen, an organoselenium compound. Therefore, these drug combinations could ensure better therapeutic outcomes than the individual agents. In this study, we developed a dry powder formulation containing remdesivir and ebselen using a spray-drying technique and used L-leucine as an aerosolization enhancer. The prepared dry powders were spherical and crystalline, with a mean particle size between 1 and 3 µm, indicating their suitability for inhalation. The emitted dose (ED) and fine particle fraction (FPF) of remdesivir- and ebselen-containing dry powders were ~80% and ~57% when prepared without L-leucine. The ED as well as the FPF significantly increased with values of >86% and >67%, respectively, when L-leucine was incorporated. More importantly, the single and combinational dry powder of remdesivir and ebselen showed minimal cytotoxicity (CC50 > 100 μM) in Calu-3 cells, retaining their anti-SARS-CoV-2 properties (EC50 2.77 to 18.64 μM). In summary, we developed an inhalable dry powder combination of remdesivir and ebselen using a spray-drying technique. The spray-dried inhalable microparticles retained their limited cytotoxicity and specific antiviral properties. Future in vivo studies are needed to verify the potential use of these remdesivir/ebselen combinational spray-dried inhalable microparticles to block the SARS-CoV-2 replication in the respiratory tract.

Recent Advances in Molecular Mechanisms of Nucleoside Antivirals

The search for new drugs has been greatly accelerated by the emergence of new viruses and drug-resistant strains of known pathogens. Nucleoside analogues (NAs) are a prospective class of antivirals due to known safety profiles, which are important for rapid repurposing in the fight against emerging pathogens. Recent improvements in research methods have revealed new unexpected details in the mechanisms of action of NAs that can pave the way for new approaches for the further development of effective drugs. This review accounts advanced techniques in viral polymerase targeting, new viral and host enzyme targeting approaches, and prodrug-based strategies for the development of antiviral NAs.