Amorphous Solid Dispersion of Niclosamide with Water-Soluble β-Cyclodextrins for Dissolution and Bioavailability Enhancement

Cyclodextrins (CDs) are cyclic oligosaccharides widely employed for the solubility enhancement of poorly water-soluble drugs. Niclosamide is a BCS class II drug for tapeworm infections and is currently under repurposing for various other indications, including COVID-19. Due to its low aqueous solubility, a high daily dose (2 g) is required for clinical efficacy. Herein, we investigate the potential of beta-cyclodextrin (β-CD) and its sulfobutylether and hydroxypropyl derivatives for the dissolution enhancement of niclosamide. The solid dispersions were prepared by kneading the drug and cyclodextrins together by adding solvent, water: methanol (1 : 1 v/v). Among various CDs studied, 2-Hydroxypropyl-β-cyclodextrin (HP-β-CD) in the 1: 2 molar ratio (SB-IC-N4 batch) shows the most significant improvement in water solubility of niclosamide (6.3 vs. 182 μg/ml), resulting in 2-fold improved in-vitro dissolution. The comparative oral pharmacokinetics in Wistar rats at 50 mg/kg produced 1.69-fold higher plasma exposure of niclosamide. The spectral characterization provided molecular insights into interactions of niclosamide with HP-β-CD. These results suggest that the dispersion of niclosamide with HP-β-CD aid in faster dissolution and better drug bioavailability. © 2023 Wiley-VCH GmbH.

Extraction of niclosamide from commercial approved tablets into aqueous buffered solution creates potentially approvable oral and nasal sprays against COVID-19 and other respiratory infections.

Motivation: The low solubility, weak acid drug, niclosamide is a host cell modulator with broad-spectrum anti-viral cell-activity against many viruses, including stopping the SARS-CoV-2 virus from infecting cells in cell culture. As a result, a simple universal nasal spray preventative was proposed and investigated in earlier work regarding the dissolution of niclosamide into simple buffers. However, starting with pharmaceutical grade, niclosamide represents a new 505(b)(2) application. The motivation for this second paper in the series was therefore to explore if and to what extent niclosamide could be extracted from commercially available and regulatory-approved niclosamide oral tablets that could serve as a preventative nasal spray and an early treatment oral/throat spray, with possibly more expeditious testing and regulatory approval. Experimental: Measurements of supernatant niclosamide concentrations were made by calibrated UV-Vis for the dissolution of niclosamide from commercially available Yomesan crushed into a powder for dissolution into Tris Buffer (TB) solutions. Parameters tested were as follows: time (0-2 days), concentration (300 µM to -1 mM), pH (7.41 to 9.35), and anhydrous/hydrated state. Optical microscopy was used to view the morphologies of the initial crushed powder, and the dissolving and equilibrating undissolved excess particles to detect morphologic changes that might occur. Results: Concentration dependence: Niclosamide was readily extracted from powdered Yomesan at pH 9.34 TB at starting Yomesan niclosamide equivalents concentrations of 300 µM, 600 µM, and 1 mM. Peak dissolved niclosamide supernatant concentrations of 264 µM, 216 µM, and 172 µM were achieved in 1 h, 1 h, and 3 h respectively. These peaks though were followed by a reduction in supernatant concentration to an average of 112.3 µM ± 28.4 µM after overnight stir on day 2. pH dependence: For nominal pHs of 7.41, 8.35, 8.85, and 9.35, peak niclosamide concentrations were 4 µM, 22.4 µM, 96.2 µM, and 215.8 µM, respectively. Similarly, the day 2 values all reduced to 3 µM, 12.9 µM, 35.1 µM, and 112.3 µM. A heat-treatment to 200 °C dehydrated the niclosamide and showed a high 3 h concentration (262 µM) and the least day-2 reduction (to 229 µM). This indicated that the presence, or formation during exposure to buffer, of lower solubility polymorphs was responsible for the reductions in total solubilities. These morphologic changes were confirmed by optical microscopy that showed initially featureless particulate-aggregates of niclosamide could grow multiple needle-shaped crystals and form needle masses, especially in the presence of Tris-buffered sodium chloride, where new red needles were rapidly made. Scale up: A scaled-up 1 L solution of niclosamide was made achieving 165 µM supernatant niclosamide in 3 h by dissolution of just one fifth (100 mg niclosamide) of a Yomesan tablet. Conclusion: These comprehensive results provide a guide as to how to utilize commercially available and approved tablets of niclosamide to generate aqueous niclosamide solutions from a simple dissolution protocol. As shown here, just one 4-tablet pack of Yomesan could readily make 165 L of a 20 µM niclosamide solution giving 16,500 10 mL bottles. One million bottles, from just 60 packs of Yomesan, would provide 100 million single spray doses for distribution to mitigate a host of respiratory infections as a universal preventative-nasal and early treatment oral/throat sprays throughout the world. Graphical Abstract: pH dependence of niclosamide extraction from crushed Yomesan tablet material into Tris buffer (yellow-green in vial) and Tris-buffered saline solution (orange-red in vial). Initial anhydrous dissolution concentration is reduced by overnight stirring to likely monohydrate niclosamide; and is even lower if in TBSS forming new niclosamide sodium needle crystals grown from the original particles. Supplementary Information: The online version contains supplementary material available at 10.1186/s41120-023-00072-x.

Synthesis, cytotoxicity, and pharmacokinetic evaluations of niclosamide analogs for anti-SARS-CoV-2.

Niclosamide, an oral anthelmintic drug, could inhibit SARS-CoV-2 virus replication through autophagy induction, but high cytotoxicity and poor oral bioavailability limited its application. Twenty-three niclosamide analogs were designed and synthesized, of which compound 21 was found to exhibit the best anti-SARS-CoV-2 efficacy (EC50 = 1.00 µM for 24 h), lower cytotoxicity (CC50 = 4.73 µM for 48 h), better pharmacokinetic, and it was also well tolerated in the sub-acute toxicity study in mice. To further improve the pharmacokinetics of 21, three prodrugs have been synthesized. The pharmacokinetics of 24 indicates its potential for further research (AUClast was 3-fold of compound 21). Western blot assay indicated that compound 21 could down-regulate SKP2 expression and increase BECN1 levels in Vero-E6 cells, indicating the antiviral mechanism of 21 was related to modulating the autophagy processes in host cells.

Use of physiological based pharmacokinetic modeling for cross-species prediction of pharmacokinetic and tissue distribution profiles of a novel niclosamide prodrug.

Introduction: Niclosamide (Nc) is an FDA-approved anthelmintic drug that was recently identified in a drug repurposing screening to possess antiviral activity against SARS-CoV-2. However, due to the low solubility and permeability of Nc, its in vivo efficacy was limited by its poor oral absorption. Method: The current study evaluated a novel prodrug of Nc (PDN; NCATS-SM4705) in improving in vivo exposure of Nc and predicted pharmacokinetic profiles of PDN and Nc across different species. ADME properties of the prodrug were determined in humans, hamsters, and mice, while the pharmacokinetics (PK) of PDN were obtained in mice and hamsters. Concentrations of PDN and Nc in plasma and tissue homogenates were measured by UPLC-MS/MS. A physiologically based pharmacokinetic (PBPK) model was developed based on physicochemical properties, pharmacokinetic and tissue distribution data in mice, validated by the PK profiles in hamsters and applied to predict pharmacokinetic profiles in humans. Results: Following intravenous and oral administration of PDN in mice, the total plasma clearance (CLp) and volume of distribution at steady-state (Vdss) were 0.061-0.063 L/h and 0.28-0.31 L, respectively. PDN was converted to Nc in both liver and blood, improving the systemic exposure of Nc in mice and hamsters after oral administration. The PBPK model developed for PDN and in vivo formed Nc could adequately simulate plasma and tissue concentration-time profiles in mice and plasma profiles in hamsters. The predicted human CLp/F and Vdss/F after an oral dose were 2.1 L/h/kg and 15 L/kg for the prodrug respectively. The predicted Nc concentrations in human plasma and lung suggest that a TID dose of 300 mg PDN would provide Nc lung concentrations at 8- to 60-fold higher than in vitro IC50 against SARS-CoV-2 reported in cell assays. Conclusion: In conclusion, the novel prodrug PDN can be efficiently converted to Nc in vivo and improves the systemic exposure of Nc in mice after oral administration. The developed PBPK model adequately depicts the mouse and hamster pharmacokinetic and tissue distribution profiles and highlights its potential application in the prediction of human pharmacokinetic profiles.

Therapeutic potential of salicylamide derivatives for combating viral infections.

Since time immemorial human beings have constantly been fighting against viral infections. The ongoing and devastating coronavirus disease 2019 pandemic represents one of the most severe and most significant public health emergencies in human history, highlighting an urgent need to develop broad-spectrum antiviral agents. Salicylamide (2-hydroxybenzamide) derivatives, represented by niclosamide and nitazoxanide, inhibit the replication of a broad range of RNA and DNA viruses such as flavivirus, influenza A virus, and coronavirus. Moreover, nitazoxanide was effective in clinical trials against different viral infections including diarrhea caused by rotavirus and norovirus, uncomplicated influenza A and B, hepatitis B, and hepatitis C. In this review, we summarize the broad antiviral activities of salicylamide derivatives, the clinical progress, and the potential targets or mechanisms against different viral infections and highlight their therapeutic potential in combating the circulating and emerging viral infections in the future.

PROphylaxis for paTiEnts at risk of COVID-19 infecTion (PROTECT-V).

BACKGROUND: Despite the introduction of vaccination, there remains a need for pre-exposure prophylactic agents against SARS-CoV-2. Several patient groups are more vulnerable to SARS-CoV-2 infection by virtue of underlying health conditions, treatments received or suboptimal responses to vaccination. METHODS: PROTECT-V is a platform trial testing pre-exposure prophylactic interventions against SARS-CoV-2 infection in vulnerable patient populations (organ transplant recipients; individuals with oncological/haematological diagnoses, immune deficiency or autoimmune diseases requiring immunosuppression or on dialysis). Multiple agents can be evaluated across multiple vulnerable populations sharing placebo groups, with the option of adding additional treatments at later time points as these become available. The primary endpoint is symptomatic SARS-CoV-2 infection, and each agent will be independently evaluated in real time when the required number of events occurs. Presently, three agents are approved in the platform: intranasal niclosamide, nasal and inhaled ciclesonide and intravenous sotrovimab. DISCUSSION: Despite the introduction of vaccination, there remains a need for pre-exposure prophylactic agents against SARS-CoV-2. Several patient groups are more vulnerable to COVID-19 disease by virtue of underlying health conditions, treatments received or suboptimal responses to vaccination. TRIAL REGISTRATION: ClinicalTrials.gov NCT04870333. EudraCT 2020-004144-28.

NICLOSAMIDE: A POTENTIAL TREATMENT OPTION FOR COVID-19

Coronavirus Disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) poses a global health hazard due to its rapid dissemination and limited treatment options. Identification of possible treatments that may kill the virus, speed up the recovery, or reduce the case fatality rate is a need of hour. However, developing and producing particular COVID-19 medicines and vaccines is a time-consuming process with possibilities of clinical failures due to safety or efficacy issue. Medication repositioning is a safer and quicker approach for dealing with the COVID-19 worldwide threat right now. Out of 48 FDA-approved medicines tested against SARS-CoV-2, niclosamide is one amongst few that has shown potential in vitro antiviral activity against SARS-CoV-2. However, the currently available oral conventional formulation of niclosamide results in systemic medication levels those are unsatisfactory to inhibit SARS-CoV-2. Hence, various formulation strategies have been adapted in order to achieve an optimum therapeutic outcome of niclosamide when delivered via oral, inhalation, and intranasal routes. Some of these formulations are presently undergoing clinical trials. The current review focuses on the mechanisms of action of niclosamide and its repurposing effectiveness against COVID-19. The delivery strategies to improve its bioavailability have been overviewed. The recently completed and ongoing clinical trials have also been summarized. © 2023 The Authors.

SARS-CoV-2 Spike protein activates TMEM16F-mediated platelet procoagulant activity.

Thrombosis of the lung microvasculature is a characteristic of COVID-19 disease, which is observed in large excess compared to other forms of acute respiratory distress syndrome and thus suggests a trigger for thrombosis that is endogenous to the lung. Our recent work has shown that the SARS-CoV-2 Spike protein activates the cellular TMEM16F chloride channel and scramblase. Through a screening on >3,000 FDA/EMA approved drugs, we identified Niclosamide and Clofazimine as the most effective molecules at inhibiting Spike-induced TMEM16 activation. As TMEM16F plays an important role in stimulating the procoagulant activity of platelets, we investigated whether Spike directly affects platelet activation and pro-thrombotic function and tested the effect of Niclosamide and Clofazimine on these processes. Here we show that Spike, present either on the virion envelope or on the cell plasma membrane, promotes platelet activation, adhesion and spreading. Spike was active as a sole agonist or, even more effectively, by enhancing the function of known platelet activators. In particular, Spike-induced a marked procoagulant phenotype in platelets, by enhancing Ca2+ flux, phosphatidylserine externalization on the platelet outer cell membrane, and thrombin generation. Eventually, this increased thrombin-induced clot formation and retraction. Both Niclosamide and Clofazimine blocked this Spike-induced procoagulant response. These findings provide a pathogenic mechanism to explain lung thrombosis-associated with severe COVID-19 infection. We propose that Spike, present in SARS-CoV-2 virions or exposed on the surface of infected cells in the lungs, enhances the effects of inflammation and leads to local platelet stimulation and subsequent activation of the coagulation cascade. As platelet TMEM16F is central in this process, these findings reinforce the rationale of repurposing Niclosamide for COVID-19 therapy.

In silico study of novel niclosamide derivatives, SARS-CoV-2 nonstructural proteins catalytic residue-targeting small molecules drug candidates.

The severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2)-mediated coronavirus disease 2019 (COVID-19) infection remains a global pandemic and health emergency with overwhelming social and economic impacts throughout the world. Therapeutics for COVID-19 are limited to only remdesivir; therefore, there is a need for combined, multidisciplinary efforts to develop new therapeutic molecules and explore the effectiveness of existing drugs against SARS-CoV-2. In the present study, we reported eight (SCOV-L-02, SCOV-L-09, SCOV-L-10, SCOV-L-11, SCOV-L-15, SCOV-L-18, SCOV-L-22, and SCOV-L-23) novel structurally related small-molecule derivatives of niclosamide (SCOV-L series) for their targeting potential against angiotensin-converting enzyme-2 (ACE2), type II transmembrane serine protease (TMPRSS2), and SARS-COV-2 nonstructural proteins (NSPs) including NSP5 (3CLpro), NSP3 (PLpro), and RdRp. Our correlation analysis suggested that ACE2 and TMPRSS2 modulate host immune response via regulation of immune-infiltrating cells at the site of tissue/organs entries. In addition, we identified some TMPRSS2 and ACE2 microRNAs target regulatory networks in SARS-CoV-2 infection and thus open up a new window for microRNAs-based therapy for the treatment of SARS-CoV-2 infection. Our in vitro study revealed that with the exception of SCOV-L-11 and SCOV-L-23 which were non-active, the SCOV-L series exhibited strict antiproliferative activities and non-cytotoxic effects against ACE2- and TMPRSS2-expressing cells. Our molecular docking for the analysis of receptor-ligand interactions revealed that SCOV-L series demonstrated high ligand binding efficacies (at higher levels than clinical drugs) against the ACE2, TMPRSS2, and SARS-COV-2 NSPs. SCOV-L-18, SCOV-L-15, and SCOV-L-09 were particularly found to exhibit strong binding affinities with three key SARS-CoV-2's proteins: 3CLpro, PLpro, and RdRp. These compounds bind to the several catalytic residues of the proteins, and satisfied the criteria of drug-like candidates, having good adsorption, distribution, metabolism, excretion, and toxicity (ADMET) pharmacokinetic profile. Altogether, the present study suggests the therapeutic potential of SCOV-L series for preventing and managing SARs-COV-2 infection and are currently under detailed investigation in our lab.

Production of a major metabolite of niclosamide using bacterial cytochrome P450 enzymes.

Niclosamide has been proposed as a possible candidate for a Covid-19 drug. However, the metabolites of niclosamide are difficult to investigate because they are usually not available commercially or they are quite expensive in the commercial market. In this study, the major metabolite of niclosamide in human liver microsomes (HLMs) was confirmed to be 3-OH niclosamide. Because the production of 3-OH niclosamide using HLMs has a slow turnover rate, a new method of producing niclosamide metabolite with an easier and highly cost-efficient method was thus conducted. Bacterial CYP102A1 (BM3) is one of the bacterial cytochrome P450s (CYPs) from Bacillus megaterium that structurally show similar activities to human CYPs. Here, the BM3 mutants were used to produce niclosamide metabolites and the metabolites were analyzed using high-performance liquid chromatography and LC-mass spectrometry. Among a set of mutants tested here, BM3 M14 mutant was the most active in producing 3-OH niclosamide, the major metabolite of niclosamide. Comparing BM3 M14 and HLMs, BM3 M14 production of 3-OH niclosamide was 34-fold higher than that of HLMs. Hence, the engineering of BM3 can be a cost-efficient method to produce 3-OH niclosamide.

Niclosamide: A Potential Treatment Option for Covid-19

Coronavirus Disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) poses a global health hazard due to its rapid dissemination and limited treatment options. Identification of possible treatments that may kill the virus, speed up the recovery, or reduce the case fatality rate is a need of hour. However, developing and producing particular COVID-19 medicines and vaccines is a time-consuming process with possibilities of clinical failures due to safety or efficacy issue. Medication repositioning is a safer and quicker approach for dealing with the COVID-19 worldwide threat right now. Out of 48 FDA-approved medicines tested against SARS-CoV-2, niclosamide is one amongst few that has shown potential in vitro antiviral activity against SARS-CoV-2. However, the currently available oral conventional formulation of niclosamide results in systemic medication levels those are unsatisfactory to inhibit SARS-CoV-2. Hence, various formulation strategies have been adapted in order to achieve an optimum therapeutic outcome of niclosamide when delivered via oral, inhalation, and intranasal routes. Some of these formulations are presently undergoing clinical trials. The current review focuses on the mechanisms of action of niclosamide and its repurposing effectiveness against COVID-19. The delivery strategies to improve its bioavailability have been overviewed. The recently completed and ongoing clinical trials have also been summarized. Copyright © 2023 The Authors.

Identification of niclosamide as a novel antiviral agent against porcine epidemic diarrhea virus infection by targeting viral internalization.

Porcine epidemic diarrhea virus (PEDV), an enteropathogenic coronavirus, has catastrophic impacts on the global pig industry. However, there remain no effective drugs against PEDV infection. In this study, we utilized a recombinant PEDV expressing renilla luciferase (PEDV-Rluc) to screen potential anti-PEDV agents from an FDA-approved drug library in Vero cells. Four compounds were identified that significantly decreased luciferase activity of PEDV-Rluc. Among them, niclosamide was further characterized because it exhibited the most potent antiviral activity with the highest selectivity index. It can efficiently inhibit viral RNA synthesis, protein expression and viral progeny production of classical and variant PEDV strains in a dose-dependent manner. Time of addition assay showed that niclosamide exhibited potent anti-PEDV activity when added simultaneously with or after virus infection. Furthermore, niclosamide significantly inhibited the entry stage of PEDV infection by affecting viral internalization rather than viral attachment to cells. In addition, a combination with other small molecule inhibitors of endosomal acidification enhanced the anti-PEDV effect of niclosamide in vitro. Taken together, these findings suggested that niclosamide is a novel antiviral agent that might provide a basis for the development of novel drug therapies against PEDV and other related pathogenic coronavirus infections.

Estimating thermodynamic equilibrium solubility and solute-solvent interactions of niclosamide in eight mono-solvents at different temperatures.

Niclosamide is an FDA-approved oral anthelmintic drug currently being repurposed for COVID-19 infection. Its interesting applicability in multiple therapeutic indications has sparked interest in this drug/ scaffold. Despite its therapeutic use for several years, its detailed solubility information from Chemistry Manufacturing & Controls perspective is unavailable. Thus, the present study is intended to determine the mole fraction solubility of niclosamide in commonly used solvents and cosolvents at a temperature range of 298.15-323.15 K. The polymorphic changes from crystalline to monohydrate forms post-equilibration in various solvents were observed. The maximum mole fraction solubility of niclosamide at 323.15 K is 1.103 × 10-3 in PEG400, followed by PEG200 (5.272 × 10-4), 1-butanol (3.047 × 10-4), 2-propanol (2.42 × 10-4), ethanol (1.66 × 10-4), DMSO (1.52 × 10-4), methanol (7.78 × 10-5) and water (3.27 × 10-7). The molecular electrostatic potential showed a linear correlation with the solubility. PEG400 has higher electrostatic potential, and H-bond acceptor count, which forms a hydrogen bond with phenolic -OH of niclosamide and thus enhances its solubility. This data is valuable for the drug discovery and development teams working on the medicinal chemistry and process chemistry of this scaffold.

Techniques for analytical estimation of COVID-19 clinical candidate, niclosamide in pharmaceutical and biomedical samples.

Niclosamide is a well-known broad-spectrum antiparasitic drug used for human as well as veterinary tapeworm infections. Recently, it attracted attention as an antiviral agent for treating coronavirus disease 2019. It is administered orally in humans to treat tapeworm infections. Furthermore, it is a registered pesticide and molluscicide to control infections in the aquaculture industry. Its chronic environmental exposure has potential toxicities when such contaminated seafood is consumed. Therefore, monitoring its residual concentration in food products (seafood, water, water waste, etc.) and pharmaceuticals (active pharmaceutical ingredients, bulk drugs, and formulations) is imperative. The present review critically investigates the sophisticated techniques employed for analyzing niclosamide, its degradation products, and metabolites in various samples and matrices. The future scope for green analytical methods, green sample extraction and preparation is also deliberated.

Allosteric inhibitors of the main protease of SARS-CoV-2.

SARS-CoV-2 has raised the alarm to search for effective therapy for this virus. To date several vaccines have been approved but few available drugs reported recently still need approval from FDA. Remdesivir was approved for emergency use only. In this report, the SARS-CoV-2 3CLpro was expressed and purified. By using a FRET-based enzymatic assay, we have screened a library consisting of more than 300 different niclosamide derivatives and identified three molecules JMX0286, JMX0301, and JMX0941 as potent allosteric inhibitors against SARS-CoV-2 3CLpro, with IC50 values similar to that of known covalent inhibitor boceprevir. In a cell-based antiviral assay, these inhibitors can inhibit the virus growth with EC50 in the range of 2-3 µM. The mechanism of action of JMX0286, JMX0301, and JMX0941 were characterized by enzyme kinetics, affinity binding and protein-based substrate digestion. Molecular docking, molecular dynamics (MD) simulations and hydration studies suggested that JMX0286, JMX0301, JMX0941 bind specifically to an allosteric pocket of the SARS-CoV-2 3CL protease. This study provides three potent compounds for further studies.

In Vitro Evaluation and Mitigation of Niclosamide's Liabilities as a COVID-19 Treatment.

Niclosamide, an FDA-approved oral anthelmintic drug, has broad biological activity including anticancer, antibacterial, and antiviral properties. Niclosamide has also been identified as a potent inhibitor of SARS-CoV-2 infection in vitro, generating interest in its use for the treatment or prevention of COVID-19. Unfortunately, there are several potential issues with using niclosamide for COVID-19, including low bioavailability, significant polypharmacology, high cellular toxicity, and unknown efficacy against emerging SARS-CoV-2 variants of concern. In this study, we used high-content imaging-based immunofluorescence assays in two different cell models to assess these limitations and evaluate the potential for using niclosamide as a COVID-19 antiviral. We show that despite promising preliminary reports, the antiviral efficacy of niclosamide overlaps with its cytotoxicity giving it a poor in vitro selectivity index for anti-SARS-CoV-2 inhibition. We also show that niclosamide has significantly variable potency against the different SARS-CoV-2 variants of concern and is most potent against variants with enhanced cell-to-cell spread including the B.1.1.7 (alpha) variant. Finally, we report the activity of 33 niclosamide analogs, several of which have reduced cytotoxicity and increased potency relative to niclosamide. A preliminary structure-activity relationship analysis reveals dependence on a protonophore for antiviral efficacy, which implicates nonspecific endolysosomal neutralization as a dominant mechanism of action. Further single-cell morphological profiling suggests niclosamide also inhibits viral entry and cell-to-cell spread by syncytia. Altogether, our results suggest that niclosamide is not an ideal candidate for the treatment of COVID-19, but that there is potential for developing improved analogs with higher clinical translational potential in the future.

Methylene blue, Mycophenolic acid, Posaconazole, and Niclosamide inhibit SARS-CoV-2 Omicron variant BA.1 infection of human airway epithelial organoids.

Sublineages of SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) Omicron variants continue to amass mutations in the spike (S) glycoprotein, which leads to immune evasion and rapid spread of the virus across the human population. Here we demonstrate the susceptibility of the Omicron variant BA.1 (B.1.1.529.1) to four repurposable drugs, Methylene blue (MB), Mycophenolic acid (MPA), Posaconazole (POS), and Niclosamide (Niclo) in post-exposure treatments of primary human airway cell cultures. MB, MPA, POS, and Niclo are known to block infection of human nasal and bronchial airway epithelial explant cultures (HAEEC) with the Wuhan strain, and four variants of concern (VoC), Alpha (B.1.1.7), Beta (B.1.351), Gamma (B.1.1.28), Delta (B.1.617.2) (Weiss et al., 2021, Murer et al., 2022). Our results here not only reinforce the broad anti-coronavirus effects of MB, MPA, POS and Niclo, but also demonstrate that the Omicron variant BA.1 (B.1.1.529.1) sheds infectious virus from HAEEC over at least 15 d, and maintains both intracellular and extracellular viral genomic RNA without overt toxicity, suggesting viral persistence. The data emphasize the potential of repurposable drugs against COVID-19.

Synergistic anti-SARS-CoV-2 activity of repurposed anti-parasitic drug combinations.

BACKGROUND: COVID-19 pandemic has claimed millions of lives and devastated the health service system, livelihood, and economy in many countries worldwide. Despite the vaccination programs in many countries, the spread of the pandemic continues, and effective treatment is still urgently needed. Although some antiviral drugs have been shown to be effective, they are not widely available. Repurposing of anti-parasitic drugs with in vitro anti-SARS-CoV-2 activity is a promising approach being tested in many clinical trials. Combination of these drugs is a plausible way to enhance their effectiveness. METHODS: The in vitro anti-SARS-CoV-2 activity of combinations of niclosamide, ivermectin and chloroquine were evaluated in Vero E6 and lung epithelial cells, Calu-3. RESULTS: All the two-drug combinations showed higher potency resulting in up to 4-fold reduction in the half maximal inhibitory concentration (IC50) values compared to individual drugs. Among these combinations, niclosamide-ivermectin achieved the highest inhibitory level of over 99%. Combination synergy analysis showed niclosamide-ivermectin combination to have the best synergy score with a mean Loewe synergy score of 4.28 and a peak synergy score of 24.6 in Vero E6 cells and a mean Loewe synergy score of 3.82 and a peak synergy score of 10.86 in Calu-3 cells. CONCLUSIONS: The present study demonstrated the benefit of drug combinations on anti-SARS-CoV-2 activity. Niclosamide and ivermectin showed the best synergistic profile and should be further tested in clinical trials.

Drug Repurposing: A Potentially Emerging Discipline

Drug repurposing is the remodeling of already existing drugs to reduce the time frame, costs, and efforts in developing a new novel drug. This strategy has secured significant momentum in the previous decade. It overcomes the snags and pitfalls in the traditional means of drug discovery. This core research strategy has now become the sole approach to containing many deadly diseases that have no cure in the present. In astound, for pandemics like COVID-19 that is spreading like a wildfire worldwide, large-scale research programs and trials have been carried out to identify and modify existing drugs to counter the novel virus. Thus, this technology of drug repurposing offers a new lease of life, and greatly promotes the progress of the medicine, health, and pharma sectors. The purpose of this study is to understand the current status of drug repurposing in the field of virology, bacteriology, mycology, and oncology for clinical translatability.

NICLOSAMIDE-EXFOLIATED ANIONIC CLAY NANOHYBRID REPURPOSED AS AN ANTIVIRAL DRUG FOR TACKLING COVID-19; ORAL FORMULATION WITH TWEEN 60/EUDRAGIT S100.

The ongoing pandemic, COVID-19 (SARS-CoV-2), has afflicted millions of people around the world, necessitating that the scientific community work, diligently and promptly, on suitable medicaments. Although vaccination programs have been run globally, the new variants of COVID-19 make it difficult to restrict the spread of the virus by vaccination alone. The combination of vaccination with anti-viral drug formulation is an ideal strategy for tackling the current pandemic situation. Drugs approved by the United States Food and Drug Administration (FDA), such as Remdesivir, have been found to be of little or no benefit. On the other hand, re-purposing of FDA-approved drugs, such as niclosamide (NIC), has offered promise but its applicability is limited due to its poor aqueous solubility and, therefore, low bioavailability. With advanced nano-pharmaceutical approaches, re-purposing this drug in a suitable drug-carrier for a better outcome may be possible. In the current study, an attempt was made to explore the loading of NIC into exfoliated layered double hydroxide nanoparticles (X-LDH NPs); prepared NIC-X-LDH NPs were further modified with eudragit S100 (ES100), an enteric coating polymer, to make the final product, ES100-NIC-X-LDH NPs, to improve absorption by the gastro/intestinal tract (GIT). Furthermore, Tween 60 was added as a coating on ES100-NIC-X-LDH NPs, not just to enhance its in vitro and in vivo stability, but also to enhance its mucoadhesive property, and to obtain, ultimately, better in vivo pharmacokinetic (PK) parameters upon oral administration. Release of NIC from Tween 60-ES100-NIC-X-LDH NPs was found to be greater under gastro/intestinal solution within a shorter period of time than the uncoated samples. The in vivo analysis revealed that Tween 60-ES100-NIC-X-LDH NPs were able to maintain a therapeutically relevant NIC plasma concentration in terms of PK parameters compared to the commercially available Yomesan®, proving that the new formulation might prove to be an effective oral drug-delivery system to deal with the SARS-CoV-2 viral infections. Further studies are required to ensure their safety and anti-viral efficacy. Supplementary Information: The online version contains supplementary material available at 10.1007/s42860-021-00153-6.