Complete poliovirus eradication requires managing chronic excreters and controlling potential outbreaks. RNA-dependent RNA Polymerase (RdRp) inhibitors represent promising candidates for this purpose. The antiviral activities of Remdesivir, Favipiravir, and Ribavirin against Sabin-like poliovirus types 1 (SL1) and 3 (SL3) were evaluated in HeLa cells individually and in combination. Antiviral effects were measured by cytopathic effect inhibition, MTT assay, and qRT-PCR. Drug-drug interactions were analyzed using Synergy Finder Plus. Molecular docking was performed to evaluate RdRp binding affinity. Remdesivir demonstrated the modest activity with low EC50 values of 47 μM (SL1) and 27 μM (SL3), while Favipiravir also showed suppression of replication at higher concentrations. Ribavirin was ineffective against SL3 and only partially inhibited SL1 at a concentration of 3500 μM. Combination treatments, especially those involving Remdesivir and Favipiravir, exhibited antagonism due to their overlapping targeting of the RdRp active site. While triple-drug treatment improved the inhibition of SL1, no additional benefit was observed against SL3. Docking analysis confirmed that Remdesivir-TP had the highest RdRp binding affinity with a ΔG value of -8.1 kcal/mol, followed by Ribavirin with -7.6 kcal/mol and Favipiravir-TP with -7.5 kcal/mol. Remdesivir and Favipiravir demonstrated notable antiviral effects against poliovirus in vitro, whereas Ribavirin showed less efficacy. Nevertheless, combining nucleoside analogues resulted in antagonistic effects, highlighting the importance of careful consideration when designing combination therapies. These results encourage continued investigation of Remdesivir and Favipiravir as potential antiviral agents for poliovirus, emphasizing the importance of selecting drugs based on their mechanisms of action in combination approaches.

Heparan sulfate (HS) can act as an attachment receptor for many different animal viruses. Virus binding to HS occurs through electrostatic interactions between the negatively charged sulfate and carboxyl groups of HS and positively charged amino acids present in viral proteins. Soluble heparin, a glycosaminoglycan related to HS, can inhibit infection by many viruses, but the clinical use of heparin is limited by its anticoagulant activity. Synthetic HS mimetics that lack anticoagulant activity have been developed and can inhibit virus infection in vitro and in vivo. Building on this precedent, we investigated inhibition of respiratory syncytial virus (RSV) and herpes simplex virus type-1 (HSV-1) by a set of tri- and tetrameric dendritic HS mimetics. Several of these compounds exhibited submicromolar inhibition of both viruses when used as receptor decoys in assays of virus entry, and a lead compound inhibited the cell-to-cell spread of RSV in vitro and RSV-mediated membrane fusion. Additionally, we observed synergistic effects when an HS mimetic was used in combination with clinical antiviral remdesivir. The solubility, lack of anticoagulant activity, and antiviral potency of these dendritic HS mimetics make them a promising new class of broad-spectrum antiviral therapeutics.

The advent of COVID-19 has highlighted the value of repurposing existing antiviral medications and the importance of developing efficient analytical methods to assist their quality control. Simultaneous determination of multiple agents saves time and resources in pharmaceutical analysis. Moreover, the analytical demand during health emergencies underscores the need for validated, rapid, and reliable methods that can support both therapeutic evaluation and regulatory decisions. In this study, we developed and optimized a reversed-phase high-performance liquid chromatography (RP-HPLC) method to measure four repurposed antiviral drugs: favipiravir, sofosbuvir, ledipasvir, and remdesivir. A Box-Behnken design (BBD) approach was employed to study how buffer pH, the amount of organic solvent in the mobile phase, and flow rate affect key outcomes like resolution and run time. The separation was done on INERTSIL ODS-3 C18 column (5 μm, 250 × 4.6 mm) under isocratic elution conditions using acetonitrile (50:50, v/v) and ammonium formate buffer (0.02 M, adjusted to pH 2.8 with formic acid) as the mobile phase at flow rate 1 mL/min. Detection was performed at 240 nm. The method demonstrated good system suitability and met ICH Q2 (R2) validation standards, exhibiting satisfactory linearity (R[2] > 0.999), accuracy (recoveries within 98-102%), and precision (RSD < 2%). The sustainability of the proposed method was comprehensively evaluated using AGREE, MoGAPI, BAGI, and RAPI tools to assess its greenness, blueness, and whiteness. The proposed method offers a practical and efficient analytical platform for quality control laboratories, enabling reliable routine analysis of multiple antiviral agents in pharmaceutical products, particularly for post-pandemic preparedness and therapeutic surveillance.

When estimating the effects of medical therapies from their use outside of randomized trials, researchers often rely on assumptions that are difficult to justify and typically impossible to verify. The resulting estimates may thus be far from their intended causal targets, potentially making a harmful treatment appear beneficial or vice versa. We review the stability-controlled quasi-experiment (SCQE), a method suited to settings where a treatment's prevalence changes sharply over a short period, and apply it to assess the effects of remdesivir, hydroxychloroquine, and dexamethasone on COVID-19 mortality. Rather than requiring debate about the absence (or limited strength) of unobserved confounding, about "parallel trends'', or other well-known strategies, the SCQE asks users to reason about a "baseline trend'' assumption. In this setting, this asks"How much could COVID-19 mortality have changed over a short period, absent the treatment change in question?'' Any plausible range for this assumption yields a corresponding range of plausible causal effect estimates. Conversely, SCQE clarifies what baseline trends must be defended or refuted in order to defend or refute a given conclusion about a treatment's efficacy or harm. Using data from two hospital systems early in the COVID-19 pandemic, we show that SCQE could have enabled safe yet informative inferences about treatment effects before clinical trial completion, producing conclusions consistent with eventual trial results.

Flavonoids are recognized for interfering with stages of SARS-CoV-2 life cycle. Then, tiliroside (kaempferol 3-O-glucoside-6''-E-coumaroyl), an O-glycosylated flavonoid isolated from Pavonia malacophylla (Link & Otto) Garcke, was investigated for its ability to block SARS-CoV-2 viral entry. Tiliroside was chemically characterized and tested for inhibition of the SARS-CoV-2 Spike receptor-binding domain (RBD)-human ACE2 interaction using a bioluminescent immunoassay. At 10 µM, it inhibited 63% of RBD:ACE2 binding. Flow cytometry and pseudovirus assays assessed Spike internalization in endothelial cells and Spike-pseudotyped infection, respectively. Flow cytometry confirmed reduced internalization after tiliroside treatment, while neutralization assays showed a dose-dependent inhibition of pseudovirus infection, with an EC50 of 18.5 µM. Molecular docking revealed strong binding of tiliroside to the Spike RBD, involving Lys417, Gly496, Tyr495, Tyr453, and Tyr505, with a predicted higher affinity than that of remdesivir and nafamostat. These results provide the first in vitro evidence that tiliroside may be a SARS-CoV-2 entry inhibitor, highlighting O-glycosylated flavonoids as antiviral scaffolds.

Background/Objectives: The purpose of this study was to investigate the association between cardiovascular adverse drug events (ADEs) and the use of COVID-19 medicines. Methods: The analyses were conducted by leveraging pharmacovigilance data from the Food and Drug Authority (FDA) Adverse Event Reporting System (FAERS) and TriNetX electronic health records (EHRs). Transcriptomic data from human embryonic stem cell-derived cardiomyocytes (hESC-CMs) exposed to remdesivir were analyzed to provide supportive biological context for the observed cardiovascular safety signals. Results: Comparative analysis of three approved COVID-19 therapies revealed that COVID-19 patients treated with remdesivir had a higher risk of cardiovascular events than those treated with Paxlovid or REGEN-COV. FAERS analysis further indicated that bradycardia, hypotension, and cardiac arrest were the most frequently reported cardiovascular events associated with remdesivir, which was validated by propensity score-matched EHR data. These findings suggest an association between remdesivir exposure and increased cardiovascular ADEs relative to other COVID-19 therapies. Sex-stratified analysis using FAERS and EHR did not show strong sex-dependent patterns for remdesivir-associated cardiovascular ADEs. Age-stratified analyses of EHR data showed age-associated variation across the three cardiovascular ADEs. Bradycardia displayed a non-uniform pattern with higher prevalence in the youngest and oldest age groups, hypotension showed an overall age-associated increase, and cardiac arrest showed only a weak age-associated effect. Pathway enrichment analysis on transcriptomic data revealed that the "cGMP-PKG signaling pathway", "dilated cardiomyopathy", and "calcium signaling pathway" were enriched among genes up-regulated by remdesivir exposure. Conclusions: In summary, our integrated analysis of pharmacovigilance, EHR, and transcriptomic data provides convergent evidence for associations between remdesivir and cardiovascular ADEs and offers biological context into these associations.

The global spread of COVID-19 led to the rapid authorization of remdesivir as the first antiviral therapy. However, accumulating clinical evidence has linked its use to cardiac adverse effects. Understanding the mechanisms underlying remdesivir-induced cardiotoxicity is critical for optimizing its clinical use and ensuring patient safety. This study investigates the electrophysiological and molecular features underlying remdesivir-induced cardiac toxicity in male and female guinea pigs, aiming to elucidate the sex-dependent differences in cardiac dysfunction and the role of mitochondria in mediating these effects. A cardiac injury model was established via intraperitoneal administration of remdesivir. In vivo telemetry and ex vivo electrocardiography were used for continuous monitoring of cardiac electrical activity, while optical mapping enabled the assessment of action potential parameters and conduction properties. The histopathological alterations and mitochondrial ultrastructure were examined by hematoxylin-eosin staining and transmission electron microscopy. ELISA and Western blot analyses were performed to explore the inflammatory signaling, apoptosis, and mitochondrial dynamics. Remdesivir induced distinct sex-specific patterns of cardiac toxicity. Compared with female guinea pigs, male guinea pigs had significantly more severe myocardial injury, which was characterized by extensive inflammatory cell infiltration, marked mitochondrial disruption, and a higher incidence of sustained ventricular tachyarrhythmia. Overall, remdesivir was associated with sex-dependent cardiac toxicity, accompanied by mitochondrial impairment and inflammatory activation. Male guinea pigs were more susceptible to electrophysiological instability and mitochondrial dysfunction. These findings highlight the importance of carefully evaluating remdesivir's cardiac effects and support the need for individualized, sex-specific considerations in its clinical administration.

BACKGROUND The coronavirus disease 2019 (COVID-19) pandemic has elucidated various extrapulmonary manifestations of severe acute respiratory syndrome coronavirus 2, including endocrine complications that affect the hypothalamic-pituitary-adrenal axis. Efforts to diagnose adrenal insufficiency in critically ill patients are challenging due to overlapping symptoms such as hypotension and fatigue. This challenge is amplified in patients with renal comorbidities, among whom classic electrolyte derangements of adrenal insufficiency (eg, hyperkalemia) may be masked by acute kidney injury (AKI) and renal replacement therapy. CASE REPORT A 46-year-old man with chronic kidney disease and an ileostomy presented with fatigue, abdominal pain, high ileostomy output, and hypotension. Evaluation revealed COVID-19 with concomitant AKI, metabolic acidosis, and hyperkalemia. Initial management via hemodialysis and remdesivir corrected the acidosis and electrolyte abnormalities. However, after renal recovery and discontinuation of dialysis, the patient developed recurrent, refractory hypotension, hyperkalemia, and hypoglycemia, prompting assessment for adrenal dysfunction. Morning cortisol levels were critically low. A subsequent cosyntropin stimulation test showed a blunted cortisol response, confirming adrenal insufficiency. Hydrocortisone and fludrocortisone treatments resulted in hemodynamic stabilization and resolution of the electrolyte abnormalities. CONCLUSIONS This case highlights the "masking" effect of dialysis on the clinical presentation of adrenal insufficiency. Clinicians must maintain a high index of suspicion for adrenal insufficiency in patients with COVID-19 who display recurrent hypotension or hyperkalemia despite renal recovery. Furthermore, the presence of hyperkalemia in a patient with high ileostomy output is paradoxical and should prompt immediate evaluation for mineralocorticoid deficiency.

Human picornavirus infections remain without approved antiviral therapies. Antiviral testing performed in immortalised cell lines often fails to predict antiviral efficacy in vivo and subsequently clinical outcomes. Here, we assessed how antiviral responses to clinically approved compounds differ between immortalised intestinal cell lines and a physiologically relevant human intestinal organoid-derived epithelium (HIE) model. Posaconazole, itraconazole, ribavirin, remdesivir, and pocapavir, compounds with reported anti-picornaviral activity in cell lines, were evaluated against enterovirus A71 (EV-A71) and human parechovirus 1 (HPeV-1) in Caco-2 and HT-29 cell lines, and human foetal HIE monolayers from multiple donors. Remdesivir consistently inhibited EV-A71 replication in Caco-2 and HT-29 cell lines, and HPeV-1 replication in Caco-2 cells, whereas the other compounds showed limited or variable effects. In contrast, in HIE, remdesivir and ribavirin reduced EV-A71 replication in only one donor, while itraconazole and posaconazole exhibited donor-specific cytotoxicity. No compound consistently inhibited HPeV-1 replication across HIE donors despite detectable antiviral effect in cell lines. Comparative analysis of drug-metabolising enzyme expression did not fully account for donor-specific response variability. Collectively, these findings reveal substantial heterogeneity in antiviral responses that is not captured by standard cell lines and underscore the value of incorporating genetically and physiologically diverse human organoid-based models into preclinical antiviral screening pipelines to improve translational fidelity.

Chronic ethanol exposure is detrimental, leading to neurodegeneration through mechanisms such as oxidative stress, inflammation, and interference with neuronal signaling pathways. In this study, a solid lipid nanoparticle formulation of remdesivir (RDV-SLNs) was evaluated for its neuroprotective effects against ethanol-induced neurodegeneration as compared to RDV dispersion. Adult male albino mice were administered ethanol, and various behavioral paradigms were used to evaluate cognitive decline. Mice exposed to ethanol exhibited notable deficits in recognition, spatial learning, and working memory. However, these impairments were significantly restored following treatment with RDV-SLNs. Furthermore, our data demonstrated a significant interaction between triggering receptors expressed on myeloid cells 1 (TREM1) (pro-inflammatory) and triggering receptor expressed on myeloid cells 2 (TREM2) (neuroprotective) in ethanol neurotoxicity, wherein their dysregulation results in NLRP3 inflammasome overactivation. Additionally, the downregulation of peroxisome proliferator-activated receptor (PPARγ) intensified this inflammatory cascade, coupled to hyper-elevated malondialdehyde (MDA) and nitric oxide (NO) levels in the ethanol-intoxicated group. Moreover, treatment with RDV-SLNs or RDV alone restored PPARγ activity and antioxidant enzymes such as catalase (CAT), glutathione (GSH), and glutathione S-transferase (GST). This restoration of PPARγ, coupled to the TREM signaling pathway balanced by RDV-SLNs, alleviated ethanol-induced neurodegeneration. These findings highlight the dual role of RDV by protecting against ethanol-induced neurodegeneration both as a modulator of neuroinflammation/oxidative stress and a metabolic regulator.

Early initiation of remdesivir (RDV) is recommended to improve COVID-19 outcomes, but real-world studies describing patterns of RDV use and related outcomes among Japanese COVID-19 patients at high-risk of severe outcomes or death are limited. This claims-based cohort study included 60,165 high-risk patients hospitalized with COVID-19 between October 2021 and June 2023 using the DeSC Healthcare claims database. Patients were categorized into early-RDV (within 2 days of hospital admission), late-RDV (between day 3 and day 7), and no-RDV groups based on RDV initiation timing. Descriptive analyses were performed according to RDV groups. Of the study patients, ≥85% were very elderly (≥75 years). Approximately 39% of patients received early RDV, 2% received late RDV, and 59% received no RDV. By day 28, the proportion of alive discharge for early-, late-, and no-RDV groups was 74.9%, 63.1%, and 71.8%, respectively. The mortality for early-, late-, and no-RDV groups was 7.7%, 8.8%, and 8.4%, respectively. Future hypothesis-driven studies with an appropriate adjustment for confounders are needed to formally evaluate the impact of RDV initiation timing on clinical outcomes in this high-risk, predominantly late-elderly population in Japan.