Is drug repurposing really the future of drug discovery or is new innovation truly the way forward?

Discovery of new antimicrobial thiophene derivatives with activity against drug-resistant Gram negative-bacteria

Our aim is to identify new small molecules with antimicrobial potential, especially against colistin-resistant (Col-R) Acinetobacter baumannii and Escherichia coli. After initial hits identification by fingerprint similarity, MIC of 24 heterocyclic derivatives for A. baumannii and E. coli reference strains, and bactericidal activity of selected thiophenes against Col-R strains were determined. We analyzed changes in bacterial membrane permeability and the OMPs profile. Additionally, we determined bacterial adherence to host cells and performed molecular docking studies to assess their binding to bacterial targets. The compounds' MICs ranged from 4 to >64 mg/L. Thiophene derivatives 4, 5 and 8 exhibited MIC50 values between 16 and 32 mg/L for Col-R A. baumannii and 8 and 32 mg/L for Col-R E. coli. The time-kill curve assay demonstrated that thiophenes 4 and 8 had bactericidal effects against Col-R A. baumannii and E. coli. Furthermore, treatment with them resulted in increased membrane permeabilization and reduced adherence of these isolates to host cells. Finally, the docking studies showed a stronger binding affinity to CarO1 and Omp33 of A. baumannii and OmpW and OmpC of E. coli. These findings indicate that thiophene derivatives possess antibacterial activity against Col-R A. baumannii and E. coli, suggesting that they may enhance the repertoire of drug treatments against bacteria.

Method to link medicines to diseases using multiplex networks

The reuse of well-established medicines using computational modeling has gained a lot of attention due to its tremendous benefits. Based on this perspective, a new method for linking known medicines to diseases is proposed. The creation of a new treatment or medicine can be financially and temporally costly and the reuse of medicines is one possibility to accelerate this process efficiently. The main purpose of the reuse of medicines is to reduce some stages of the development of new medicines, motivating the proposition of several methods nowadays. In this work, a new method is developed aiming to connect known medicines to diseases based on available networks of protein interactions and available lists of medicines that affect protein action. The concepts of multiplex networks are used to connect subgraphs of vertices that represent medicines and proteins. The core of the procedure is determined by a weighting strategy constructed to define precisely the more relevant connections. The method was compared to other network link methods in the literature and a case study was presented and evaluated by the proposed method.

Reimagining old drugs with new tricks: Mechanisms, strategies and notable success stories in drug repurposing for neurological diseases

Recent evolution in drug repurposing has brought new anticipation, especially in the conflict against neurodegenerative diseases (NDDs). The traditional approach to developing novel drugs for these complex disorders is laborious, time-consuming, and often abortive. However, drug reprofiling which is the implementation of illuminating novel therapeutic applications of existing approved drugs, has shown potential as a promising strategy to accelerate the hunt for therapeutics. The advancement of computational approaches and artificial intelligence has expedited drug repurposing. These progressive technologies have enabled scientists to analyse extensive datasets and predict potential drug-disease interactions. By prospecting into the existing pharmacological knowledge, scientists can recognise potential therapeutic candidates for reprofiling, saving precious time and resources. Preclinical models have also played a pivotal role in this field, confirming the effectiveness and mechanisms of action of repurposed drugs. Several studies have occurred in recent years, including the discovery of available drugs that demonstrate significant protective effects in NDDs, relieve debilitating symptoms, or slow down the progression of the disease. These findings highlight the potential of repurposed drugs to change the landscape of NDD treatment. Here, we present an overview of recent developments and major advances in drug repurposing intending to provide an in-depth analysis of traditional drug discovery and the strategies, approaches and technologies that have contributed to drug repositioning. In addition, this chapter attempts to highlight successful case studies of drug repositioning in various therapeutic areas related to NDDs and explore the clinical trials, challenges and limitations faced by researchers in the field. Finally, the importance of drug repositioning in drug discovery and development and its potential to address discontented medical needs is also highlighted.

Multitarget Potential Drug Candidates for High-Grade Gliomas Identified by Multiple Reaction Monitoring Coupled with In Silico Drug Repurposing

High-grade gliomas (HGGs) are extremely aggressive primary brain tumors with high mortality rates. Despite notable progress achieved by clinical research and biomarkers emerging from proteomics studies, efficacious drugs and therapeutic targets are limited. This study used targeted proteomics, in silico molecular docking, and simulation-based drug repurposing to identify potential drug candidates for HGGs. Importantly, we performed multiple reaction monitoring (MRM) on differentially expressed proteins with putative roles in the development and progression of HGGs based on our previous work and the published literature. Furthermore, in silico molecular docking-based drug repurposing was performed with a customized library of FDA-approved drugs to identify multitarget-directed ligands. The top drug candidates such as Pazopanib, Icotinib, Entrectinib, Regorafenib, and Cabozantinib were explored for their drug-likeness properties using the SwissADME. Pazopanib exhibited binding affinities with a maximum number of proteins and was considered for molecular dynamic simulations and cell toxicity assays. HGG cell lines showed enhanced cytotoxicity and cell proliferation inhibition with Pazopanib and Temozolomide combinatorial treatment compared to Temozolomide alone. To the best of our knowledge, this is the first study combining MRM with molecular docking and simulation-based drug repurposing to identify potential drug candidates for HGG. While the present study identified five multitarget-directed potential drug candidates, future clinical studies in larger cohorts are crucial to evaluate the efficacy of these molecular candidates. The research strategy and methodology used in the present study offer new avenues for innovation in drug discovery and development which may prove useful, particularly for cancers with low cure rates.

Anticancer Drug Discovery By Structure-Based Repositioning Approach

Despite the tremendous progress that has occurred in recent years in cell biology and oncology, in chemical, physical and computer sciences, the disease cancer has continued as the major cause of death globally. Research organizations, academic institutions and pharmaceutical companies invest huge amounts of money in the discovery and development of new anticancer drugs. Though much effort is continuing and whatever available approaches are being attempted, the success of bringing one effective drug into the market has been uncertain. To overcome problems associated with drug discovery, several approaches are being attempted. One such approach has been the use of known, approved and marketed drugs to screen these for new indications, which have gained considerable interest. This approach is known in different terms as "drug repositioning or drug repurposing." Drug repositioning refers to the structure modification of the active molecule by synthesis, in vitro/ in vivo screening and in silico computational applications where macromolecular structure-based drug design (SBDD) is employed. In this perspective, we aimed to focus on the application of repositioning or repurposing of essential drug moieties present in drugs that are already used for the treatment of some diseases such as diabetes, human immunodeficiency virus (HIV) infection and inflammation as anticancer agents. This review thus covers the available literature where molecular modeling of drugs/enzyme inhibitors through SBDD is reported for antidiabetics, anti-HIV and inflammatory diseases, which are structurally modified and screened for anticancer activity using respective cell lines.

Human-virus protein-protein interactions maps assist in revealing the pathogenesis of viral infection

Many significant viral infections have been recorded in human history, which have caused enormous negative impacts worldwide. Human-virus protein-protein interactions (PPIs) mediate viral infection and immune processes in the host. The identification, quantification, localization, and construction of human-virus PPIs maps are critical prerequisites for understanding the biophysical basis of the viral invasion process and characterising the framework for all protein functions. With the technological revolution and the introduction of artificial intelligence, the human-virus PPIs maps have been expanded rapidly in the past decade and shed light on solving complicated biomedical problems. However, there is still a lack of prospective insight into the field. In this work, we comprehensively review and compare the effectiveness, potential, and limitations of diverse approaches for constructing large-scale PPIs maps in human-virus, including experimental methods based on biophysics and biochemistry, databases of human-virus PPIs, computational methods based on artificial intelligence, and tools for visualising PPIs maps. The work aims to provide a toolbox for researchers, hoping to better assist in deciphering the relationship between humans and viruses.

FSIP1 enhances the therapeutic sensitivity to CDK4/6 inhibitors in triple-negative breast cancer patients by activating the Nanog pathway

CDK4/6 inhibitors are routinely recommended agents for the treatment of advanced HR+HER2- breast cancer. However, their therapeutic effectiveness in triple-negative breast cancer (TNBC) remains controversial. Here, we observed that the expression level of fibrous sheath interacting protein 1 (FSIP1) could predict the treatment response of TNBC to CDK4/6 inhibitors. High FSIP1 expression level was related to a poor prognosis in TNBC, which was associated with the ability of FSIP1 to promote tumor cell proliferation. FSIP1 downregulation led to slowed tumor growth and reduced lung metastasis in TNBC. FSIP1 knockout caused cell cycle arrest at the G0/G1 phase and reduced treatment sensitivity to CDK4/6 inhibitors by inactivating the Nanog/CCND1/CDK4/6 pathway. FSIP1 could form a complex with Nanog, protecting it from ubiquitination and degradation, which may facilitate the rapid cell cycle transition from G0/G1 to S phase and exhibit enhanced sensitivity to CDK4/6 inhibitors. Our findings suggest that TNBC patients with high FSIP1 expression levels may be suitable candidates for CDK4/6 inhibitor treatment.

Research Attitude and Interest among Cancer Survivors with or without Cognitive Impairment

BACKGROUND

We examined the research attitudes and willingness to participate in clinical research among cancer survivors with varying degrees of cognitive function.

METHODS

This is a secondary analysis of data collected through the University of California Irvine Consent-to-Contact registry. Cancer survivors completed the Cognitive Function Instrument (CFI), the Research Attitudes Questionnaire (RAQ), and willingness to participate (WTP) in certain research procedures. Perceived cognitive impairment (CI) was defined as the worst 20% CFI scores.

RESULTS

Here, 265 CI and 909 cognitively non-impaired (CNI) participants' data were analyzed. Mean age and sex distribution were similar, with fewer non-Hispanic Whites and education years among CI participants. More CI participants self-reported past diagnoses of Alzheimer's disease, mild cognitive impairment, stroke, depression, post-traumatic stress disorder, and alcohol abuse (all p < 0.05). CI participants were significantly more interested in studies investigating approved medications (92% vs. 87%, p = 0.030), lumbar puncture (47% vs. 38%, p = 0.027), and autopsy (78% vs. 69%, p = 0.022). After removing survivors with co-existing neuropsychiatric conditions, interest in autopsy studies remained statistically higher among CI (79% vs. 69%, p = 0.022).

CONCLUSIONS

Participants with cancer and CI are open to research procedures and interventions that are traditionally less utilized, which may facilitate the discovery of the pathogenesis and interventions for cancer-related cognitive impairment (CRCI).

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

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

Docking and Molecular Dynamics Identify Leads against 5 Alpha Reductase 2 for Benign Prostate Hyperplasia Treatment

Steroid 5 alpha-reductase 2 (5αR-2) is a membrane-embedded protein that together with other isoforms plays a key role in the metabolism of steroids. This enzyme catalyzes the reduction of testosterone to the more potent ligand, dihydrotestosterone (DHT) in the prostate. Androgens, testosterone, and DHT play important roles in prostate growth, development, and function. At the same time, both testosterone and DHT have been implicated in the pathogenesis of benign prostate hyperplasia (BPH). Inhibition of the DHT formation, therefore, provides a therapeutic strategy that offers the possibility of preventing, delaying, or treating BPH. Currently, two steroidal drugs that inhibit 5αR-2, dutasteride and finasteride, have been approved for clinical use. These two come at a high cost and also portray undesirable sexual side effects which necessitate the need to find new chemotherapeutic alternatives for the disease. Based on the aforementioned, finasteride and dutasteride were subjected to scaffold hopping, fragment-based de novo design, molecular docking, and molecular dynamics simulations employing databases like ChEMBL, DrugBank, PubChem, ChemSpider, and Zinc15 in the identification of potential hits targeting 5αR-2. Altogether, ten novel compounds targeting 5αR-2 were identified with binding energies lower or comparable to finasteride and dutasteride, the main inhibitors for this target. Molecular docking and molecular dynamics simulations studies identify amino acid residues Glu57, Phe219, Phe223, and Leu224 to be critical for ligand binding and complex stability. The physicochemical and pharmacological profiling suggests the potential of the hit compounds to be drug-like and orally active. Similarly, the quality parameter assessments revealed the hits possess LELP greater than 3 implying their promise as lead-like molecules. The compounds A5, A9, and A10 were, respectively, predicted to treat prostate disorders with Pa (0.188, 0.361, and 0.270) and Pi (0.176, 0.050, and 0.093), while A8 and A9 were found to be associated with BPH treatment with Pa (0.09 and 0.127) and Pi (0.077 and 0.033), respectively. Structural similarity searches via DrugBank identified the drugs faropenem, acemetacin, estradiol valerate, and yohimbine to be useful for BPH treatment suggesting the de novo designed ligands as potential chemotherapeutic agents for treating this disease.

Targeting mitochondrial impairment for the treatment of cardiovascular diseases: From hypertension to ischemia-reperfusion injury, searching for new pharmacological targets

Mitochondria and mitochondrial proteins represent a group of promising pharmacological target candidates in the search of new molecular targets and drugs to counteract the onset of hypertension and more in general cardiovascular diseases (CVDs). Indeed, several mitochondrial pathways result impaired in CVDs, showing ATP depletion and ROS production as common traits of cardiac tissue degeneration. Thus, targeting mitochondrial dysfunction in cardiomyocytes can represent a successful strategy to prevent heart failure. In this context, the identification of new pharmacological targets among mitochondrial proteins paves the way for the design of new selective drugs. Thanks to the advances in omics approaches, to a greater availability of mitochondrial crystallized protein structures and to the development of new computational approaches for protein 3D-modelling and drug design, it is now possible to investigate in detail impaired mitochondrial pathways in CVDs. Furthermore, it is possible to design new powerful drugs able to hit the selected pharmacological targets in a highly selective way to rescue mitochondrial dysfunction and prevent cardiac tissue degeneration. The role of mitochondrial dysfunction in the onset of CVDs appears increasingly evident, as reflected by the impairment of proteins involved in lipid peroxidation, mitochondrial dynamics, respiratory chain complexes, and membrane polarization maintenance in CVD patients. Conversely, little is known about proteins responsible for the cross-talk between mitochondria and cytoplasm in cardiomyocytes. Mitochondrial transporters of the SLC25A family, in particular, are responsible for the translocation of nucleotides (e.g., ATP), amino acids (e.g., aspartate, glutamate, ornithine), organic acids (e.g. malate and 2-oxoglutarate), and other cofactors (e.g., inorganic phosphate, NAD⁺, FAD, carnitine, CoA derivatives) between the mitochondrial and cytosolic compartments. Thus, mitochondrial transporters play a key role in the mitochondria-cytosol cross-talk by leading metabolic pathways such as the malate/aspartate shuttle, the carnitine shuttle, the ATP export from mitochondria, and the regulation of permeability transition pore opening. Since all these pathways are crucial for maintaining healthy cardiomyocytes, mitochondrial carriers emerge as an interesting class of new possible pharmacological targets for CVD treatments.

Utilizing clinical pharmacology in the drug repurposing arena: a look into COVID-19

INTRODUCTION

Drug repurposing represented an important contribution in the management of COVID-19, becoming the first line of defense to mitigate the effects of the new coronavirus. In a brief time, drug repurposing (DR) provided potentially effective and already available drugs for COVID-19, while specific therapies against SARS-CoV-2 and/or vaccines were developing. Identifying repurposed drugs requires a multidisciplinary approach, where clinical pharmacology represents the missing piece of the puzzle.

AREAS COVERED

Nowadays, clinical pharmacology is recognized as a discipline at the core of translational science, whose activities lead to the identification of the right drug for the right patient. In the context of the COVID-19 pandemic, its role in drug development and therapy choice has been decisive and itself repositioned. In this review, we tried to highlight the important role of clinical pharmacology in the identification and evaluation of possible repurposed drugs for COVID-19.

EXPERT OPINION

We believe that clinical pharmacology had an important role in identifying patient-oriented therapy during the COVID-19 pandemic. In this context, DR was just one of the challenges for clinical pharmacology, which proved that this discipline is ready to respond to future threats.

Repositioning of tubocurarine as analgesic and anti-inflammatory agent: Exploring beyond myorelaxant activity

BACKGROUND AND PURPOSE

Tubocurarine (d-TC), a non-depolarizing competitive blocker of nicotinic acetylcholine receptors is extensively utilized for the relaxation of skeletal muscles. Drug repositioning is a forthright approach to reduce the cost and speed up drug development process. Herein, we have attempted to evaluate the analgesic and anti-inflammatory activity of d-TC for its possible repurposing in pain and inflammation-related issues.

EXPERIMENTAL APPROACH

We examined the soluble epoxide hydrolase inhibitory (sEHI) activity of d-TC employing in silico high throughput screening protocols, in vitro cell-free sEH inhibitory assay, and in in vivo rodent models for its repositioning in pain and inflammation-related disorders.

KEY RESULTS

In molecular docking study, d-TC displayed impressive hydrogen bonding interactions within the cavity of sEH enzyme with good docking score. d-TC also exhibited notable sEH inhibitory activity (IC₅₀ 3.72 nm) at the in vitro assay. Oral absorption capability of d-TC (0.1 and 0.2 mg/mL) was determined using an in vitro everted intestinal sac model employing rat ileum tissue that revealed significant oral absorption of d-TC. Besides, in vivo studies revealed that oral administration of d-TC (0.1 and 0.2 mg/kg) in rodents significantly attenuated hyperalgesia (cold plate test, tail immersion test and formalin test) and inflammation (estimation of rectal temperature, acetic acid induced pleurisy test and cotton pellet-induced granuloma test) induced in robust preclinical models. Conclusion and implications These findings are novel and warrant immediate efforts to reposition d-TC as a new therapeutic candidate in the management of hyperalgesia, inflammation, and associated conditions.

Homology Modeling, de Novo Design of Ligands, and Molecular Docking Identify Potential Inhibitors of Leishmania donovani 24-Sterol Methyltransferase

The therapeutic challenges pertaining to leishmaniasis due to reported chemoresistance and toxicity necessitate the need to explore novel pathways to identify plausible inhibitory molecules. Leishmania donovani 24-sterol methyltransferase (LdSMT) is vital for the synthesis of ergosterols, the main constituents of Leishmania cellular membranes. So far, mammals have not been shown to possess SMT or ergosterols, making the pathway a prime candidate for drug discovery. The structural model of LdSMT was elucidated using homology modeling to identify potential novel 24-SMT inhibitors via virtual screening, scaffold hopping, and de-novo fragment-based design. Altogether, six potential novel inhibitors were identified with binding energies ranging from −7.0 to −8.4 kcal/mol with e-LEA3D using 22,26-azasterol and S1–S4 obtained from scaffold hopping via the ChEMBL, DrugBank, PubChem, ChemSpider, and ZINC15 databases. These ligands showed comparable binding energy to 22,26-azasterol (−7.6 kcal/mol), the main inhibitor of LdSMT. Moreover, all the compounds had plausible ligand efficiency-dependent lipophilicity (LELP) scores above 3. The binding mechanism identified Tyr92 to be critical for binding, and this was corroborated via molecular dynamics simulations and molecular mechanics Poisson–Boltzmann surface area (MM-PBSA) calculations. The ligand A1 was predicted to possess antileishmanial properties with a probability of activity (Pa) of 0.362 and a probability of inactivity (Pi) of 0.066, while A5 and A6 possessed dermatological properties with Pa values of 0.205 and 0.249 and Pi values of 0.162 and 0.120, respectively. Structural similarity search via DrugBank identified vabicaserin, daledalin, zanapezil, imipramine, and cefradine with antileishmanial properties suggesting that the de-novo compounds could be explored as potential antileishmanial agents.

Anti-Inflammatory Effects of Spiramycin in LPS-Activated RAW 264.7 Macrophages

Drug repurposing is a simple concept with a long history, and is a paradigm shift that can significantly reduce the costs and accelerate the process of bringing a new small-molecule drug into clinical practice. We attempted to uncover a new application of spiramycin, an old medication that was classically prescribed for toxoplasmosis and various other soft-tissue infections; specifically, we initiated a study on the anti-inflammatory capacity of spiramycin. For this purpose, we used murine macrophage RAW 264.7 as a model for this experiment and investigated the anti-inflammatory effects of spiramycin by inhibiting the production of pro-inflammatory mediators and cytokines. In the present study, we demonstrated that spiramycin significantly decreased nitric oxide (NO), interleukin (IL)-1β, and IL-6 levels in lipopolysaccharide (LPS)-stimulated RAW 264.7 cells. Spiramycin also inhibited the expression of NO synthase (iNOS), potentially explaining the spiramycin-induced decrease in NO production. In addition, spiramycin inhibited the phosphorylation of mitogen-activated protein kinases (MAPKs); extracellular signal-regulated kinase (ERK) and c-Jun N terminal kinase (JNK) as well as the inactivation and subsequent nuclear translocation of nuclear factor κB (NF-κB). This indicated that spiramycin attenuates macrophages’ secretion of IL-6, IL-1β, and NO, inducing iNOS expression via the inhibition of the NF-κB and MAPK signaling pathways. Finally, we tested the potential application of spiramycin as a topical material by human skin primary irritation tests. It was performed on the normal skin (upper back) of 31 volunteers to determine whether 100 μM and μM of spiramycin had irritation or sensitization potential. In these assays, spiramycin did not induce any adverse reactions. In conclusion, our results demonstrate that spiramycin can effectively attenuate the activation of macrophages, suggesting that spiramycin could be a potential candidate for drug repositioning as a topical anti-inflammatory agent.

Drug Investigation to Dampen the Comorbidity of Rheumatoid Arthritis and Osteoporosis via Molecular Docking Test

At present, most rheumatoid arthritis (RA) patients are at risk of osteoporosis (OP), which is increased by 1.5 times compared to non-RA individuals. Hence, we investigated overlapping targets related directly to the occurrence and development of RA and OP through public databases (DisGeNET, and OMIM) and literature. A total of 678 overlapping targets were considered as comorbid factors, and 604 out of 678 were correlated with one another. Interleukin 6 (IL-6), with the highest degree of value in terms of protein−protein interaction (PPI), was considered to be a core target against comorbidity. We identified 31 existing small molecules (< 1000 g/mol) as IL-6 inhibitors, and 19 ligands were selected by the 3 primary criteria (Lipinski’s rule, TPSA, and binding energy). We postulated that MD2-TLR4-IN-1 (PubChem ID: 138454798), as confirmed by the three criteria, was the key ligand to alleviate comorbidity between RA and OP. In conclusion, we described a promising active ligand (MD2-TLR4-IN-1), and a potential target (IL-6) against comorbidity of RA and OP, providing scientific evidence for a further clinical trial.

AI-powered drug repurposing for developing COVID-19 treatments

Emerging infectious diseases are an ever-present threat to public health, and COVID-19 is the most recent example. There is an urgent need to develop a robust framework to combat the disease with safe and effective therapeutic options. Compared to de novo drug discovery, drug repurposing may offer a lower-cost and faster drug discovery paradigm to explore potential treatment options of existing drugs. This chapter elucidates the advantages of artificial intelligence (AI) in enhancing the drug repurposing process from a data science perspective, using COVID-19 as an example. First, we elaborate on how AI-powered drug repurposing benefits from the accumulated data and knowledge of COVID-19 natural history and pathogenesis. Second, we summarize the pros and cons of AI-powered drug repurposing strategies to facilitate fit-for-purpose selection. Finally, we outline challenges of AI-powered drug repurposing from a regulatory perspective and suggest some potential solutions.

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AI-powered drug purposing is promising for emerging treatments for COVID-19 infection.

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Accumulated biological data profiles facilitate AI-based drug repurposing efforts for development of COVID-19 therapies.

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The ‘fit-for-purpose selection of AI-powered drug repurposing strategies is key to uncovering hidden information among drugs, targets, and diseases.

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Efforts from different stakeholders boost the adoption of AI-powered drug repurposing in the regulatory setting.

Identification of potential inhibitors of SARS-CoV-2 S protein-ACE2 interaction by in silico drug repurposing

Background: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), a new coronavirus discovered that appeared in Wuhan, China, in December 2019, causes COVID-19 disease which have resulted in cases similar to SARS-atypical pneumonia. Worldwide, around 116 million cases and 2.57 million deaths are reported with new cases and increasing mortality every day. To date, there is no specific commercial treatment to control the infection. Repurpose drugs targeting the angiotensin-converting enzyme 2 (ACE2) receptor represents an alternative strategy to block the binding of SARS-CoV-2 protein S and forestall virus adhesion, internalization, and replication in the host cell.

Methods: We performed a rigid molecular docking using the receptor binding domain of the S1 subunit of S protein (RBD _S1)-ACE2 (PDB ID: 6VW1) interaction site and 1,283 drugs FDA approved. The docking score, frequency of the drug in receptor site, and interactions at the binding site residues were used as analyzing criteria.

Results: This research yielded 40 drugs identified as a potential inhibitor of RBD _S1-ACE2 interaction. Among the inhibitors, compounds such as ipratropium, formoterol, and fexofenadine can be found. Specialists employ these drugs as therapies to treat chronic obstructive pulmonary disease, asthma and virtually any respiratory infection.

Conclusions: Our results will serve as the basis for in vitro and in vivo studies to evaluate the potential use of those drugs to generate affordable and convenient therapies to treat COVID-19.