Amantadine for COVID-19

AbstractThe dire need for COVID-19 treatments has inspired strategies of repurposing approved drugs. Amantadine has been suggested as a candidate, and cellular as well as clinical studies have indicated beneficial effects of this drug. We demonstrate that amantadine and hexamethylene-amiloride (HMA), but not rimantadine, block the ion channel activity of Protein E from SARS-CoV-2, a conserved viroporin among coronaviruses. These findings agree with their binding to Protein E as evaluated by solution NMR and molecular dynamics simulations. Moreover, we identify two novel viroporins of SARS-CoV-2; ORF7b and ORF10, by showing ion channel activity in a X. laevis oocyte expression system. Notably, amantadine also blocks the ion channel activity of ORF10, thereby providing two ion channel targets in SARS-CoV-2 for amantadine treatment in COVID-19 patients. A screen of known viroporin inhibitors on Protein E, ORF7b, ORF10 and Protein 3a from SARS-CoV-2 revealed inhibition of Protein E and ORF7b by emodin and xanthene, the latter also blocking Protein 3a. This illustrates a general potential of well-known ion channel blockers against SARS-CoV-2 and specifically a dual molecular basis for the promising effects of amantadine in COVID-19 treatment.

Abstract The dire need for therapies against SARS-CoV-2 infections is obvious and inspires strategies of repurposing drugs approved for other indications. Current examples are remdesivir (originally developed for ebola treatment) and steroids (anti-inflammatory treatment). Here we propose to use amantadine (an anti-influenza A drug) as a novel, cheap, readily available and effective way to treat COVID-19 because of its ability to inhibit known (Protein E) and novel (Orf10) ion channels identified in the virus genome.

Since the SARS-CoV-2 pandemic started in late 2019, the search for protective vaccines and for drug treatments has become mandatory to fight the global health emergency. Travel restrictions, social distancing, and face masks are suitable counter measures, but may not bring the pandemic under control because people will inadvertently or at a certain degree of restriction severity or duration become incompliant with the regulations. Even if vaccines are approved, the need for antiviral agents against SARS-CoV-2 will persist. However, unequivocal evidence for efficacy against SARS-CoV-2 has not been demonstrated for any of the repurposed antiviral drugs so far. Amantadine was approved as an antiviral drug against influenza A, and antiviral activity against SARS-CoV-2 has been reasoned by analogy but without data. We tested the efficacy of amantadine in vitro in Vero E6 cells infected with SARS-CoV-2. Indeed, amantadine inhibited SARS-CoV-2 replication in two separate experiments with IC50 concentrations between 83 and 119 µM. Although these IC50 concentrations are above therapeutic amantadine levels after systemic administration, topical administration by inhalation or intranasal instillation may result in sufficient amantadine concentration in the airway epithelium without high systemic exposure. However, further studies in other models are needed to prove this hypothesis.

AbstractTo discover new drugs to combat COVID-19, an understanding of the molecular basis of SARS-CoV-2 infection is urgently needed. Here, for the first time, we report the crucial role of cathepsin L (CTSL) in patients with COVID-19. The circulating level of CTSL was elevated after SARS-CoV-2 infection and was positively correlated with disease course and severity. Correspondingly, SARS-CoV-2 pseudovirus infection increased CTSL expression in human cells in vitro and human ACE2 transgenic mice in vivo, while CTSL overexpression, in turn, enhanced pseudovirus infection in human cells. CTSL functionally cleaved the SARS-CoV-2 spike protein and enhanced virus entry, as evidenced by CTSL overexpression and knockdown in vitro and application of CTSL inhibitor drugs in vivo. Furthermore, amantadine, a licensed anti-influenza drug, significantly inhibited CTSL activity after SARS-CoV-2 pseudovirus infection and prevented infection both in vitro and in vivo. Therefore, CTSL is a promising target for new anti-COVID-19 drug development.

Coronavirus Disease 2019 (COVID-19) infection, the pandemics, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has no known effective radical pharmacotherapy and just supportive approach at present. Amantadine is a drug used in Parkinson’s disease and other parkinsonisms; and is known to increase indirectly dopamine by antagonistic effects at the N-methyl-Daspartate (NMDA) receptor by increasing the release and blocking the reuptake of dopamine. Initially, amantadine was approved as an antiviral drug. We hypothesize that if amantadine is considered its antiviral, immunological and neurostimulant effects might be useful in the supportive treatment of SARSCoV- 2 cases, especially those who developed acute respiratory failure with decreased vigilance and are being monitored in the intensive care unit. Further phase III clinical trials are needed.

Abstract Introduction: Coronavirus disease 19 (COVID-19) rapidly spread worldwide. The search for effective measures to counter the development and effects of the pandemic includes: identifying the disease pathogen, introducing methods of reducing its transmission, building the population immunity, and the search for a cure, both among the new and already-known substances with potential antivirus activity such as amantadine hydrochloride.Study objectives: The study's aim is an observational single-center analysis of confirmed COVID-19 cases treated with amantadine in ambulatory settings.Patients and methods: The group of 55 patients with confirmed COVID-19 diagnosis was treated in ambulatory settings by amantadine with a treatment schema. A retrospective analysis was based on symptoms, hospitalization, and number of deaths.Results: The mean age of the patients was 55.9 years (SD=15), and most patients were male (60%). Despite the majority of patients 64% (n=35) suffering from comorbidities and 53% (n=29) of patients having been diagnosed with pneumonia, none of them died, and only four had required hospitalization in the course of COVID-19. Clinical stabilization was achieved in 91% (n=50) of patients within 48 hours after the first dose of amantadine with further improvement; additionally, all patients experienced remission of COVID-19. In total, 93% (n=51) of patients did not require hospitalization during the treatment.Conclusions: The data may suggest that amantadine hydrochloride shows efficacy in preventing hospitalization and deaths in patients with COVID-19. At the same time, it emphasizes that daily monitoring of the patient and regular examination are important in the case of SARS-CoV-2 infection dynamics.

AbstractMany COVID-19 survivors experience lingering post-COVID-19 symptoms, notably chronic fatigue persisting for months after the acute phase. Despite its prevalence, limited research has explored effective treatments for post-COVID-19 fatigue. This randomized controlled clinical trial assessed the impact of Amantadine on patients with post-COVID-19 fatigue. The intervention group received Amantadine for two weeks, while the control group received no treatment. Fatigue levels were assessed using the Visual Analog Fatigue Scale (VAFS) and Fatigue Severity Scale (FSS) questionnaires before and after the trial. At the study's onset, VAFS mean scores were 7.90 ± 0.60 in the intervention group and 7.34 ± 0.58 in the control group (P-value = 0.087). After two weeks, intervention group scores dropped to 3.37 ± 0.44, significantly lower than the control group's 5.97 ± 0.29 (P-value < 0.001). Similarly, FSS mean scores at the trial's commencement were 53.10 ± 5.96 in the intervention group and 50.38 ± 4.88 in the control group (P-value = 0.053). At the trial's end, intervention group scores decreased to 28.40 ± 2.42, markedly lower than the control group's 42.59 ± 1.50 (P-value < 0.001). In this study, we report the safety, tolerability, and substantial fatigue-relieving effects of Amantadine in post-COVID-19 fatigue. The intervention demonstrates a statistically significant reduction in fatigue levels, suggesting Amantadine's potential as an effective treatment for this persistent condition.

AbstractBackground and purposeAdamantanes were listed as an interesting option as an early intervention against COVID‐19. We aimed to evaluate the effectiveness of amantadine in preventing the progression of COVID‐19 and its neurological sequelae.MethodsUnvaccinated patients with confirmed SARS‐CoV‐2 infection within 5 days were enrolled. Subjects were randomized (50:50) to amantadine (AMD; 100 mg twice daily) or placebo (PLB) for 14 days. The Ordinal Scale for Clinical Improvement of the World Health Organization (OSCI‐WHO) was the primary measure. Secondary endpoints included assessment for fatigue; depression, disorders of smell and taste, and sleepiness on Days 1 and 15.ResultsWe enrolled 99 patients (49 AMD and 50 PLB). Disease progression (OSCI‐WHO = 4) was observed in 6% (AMD) and 8% (PLB) patients (p > 0.05) with further deterioration (OSCI‐WHO〉4) in 0% (AMD) and 8% (PLB) patients (p > 0.05). Complete recovery on Day 15 was 60% higher in the AMD compared with the PLB group (p = 0.025). There was improvement in taste (AMD: p = 0.003; PLB: p = 0.0001) and smell (AMD: p = 0.005; PLB: p = 0.0004) but not in fatigue in both groups. Improvement was observed in the AMD (p = 0.010) but not in the PLB group (p = 0.058) when assessing depression as well as sleepiness (AMD: p = 0.0002; PLB: p = 0.341). There was one death in the PLB group (2.0%) and none in the AMD group (p > 0.05) until Day 210. Overall, the drug was well tolerated.ConclusionThe central effects of amantadine on the nervous system with reduction of sleepiness and depression might have had a supportive effect on faster recovery in early COVID‐19 patients.

Amidst the ongoing global challenge of the SARS-CoV-2 pandemic, the quest for effective antiviral medications remains paramount. This comprehensive review delves into the dynamic landscape of FDA-approved medications repurposed for COVID-19, categorized as antiviral and non-antiviral agents. Our focus extends beyond conventional narratives, encompassing vaccination targets, repurposing efficacy, clinical studies, innovative treatment modalities, and future outlooks. Unveiling the genomic intricacies of SARS-CoV-2 variants, including the WHO-designated Omicron variant, we explore diverse antiviral categories such as Fusion inhibitors, Protease inhibitors, Transcription inhibitors, Neuraminidase inhibitors, Nucleoside reverse transcriptase, and non-antiviral interventions like Importin α/β1-mediated nuclear import inhibitors, Neutralizing antibodies and convalescent plasma. Notably, Molnupiravir emerges as a pivotal player, now licensed in the UK. This review offers a fresh perspective on the historical evolution of COVID-19 therapeutics, from repurposing endeavors to the latest developments in oral anti-SARS-CoV-2 treatments, ushering in a new era of hope in the battle against the pandemic.

AbstractThe outbreak of COVID-19 has become a global crisis, and brought severe disruptions to societies and economies. Until now, effective therapeutics against COVID-19 are in high demand. Along with our improved understanding of the structure, function, and pathogenic process of SARS-CoV-2, many small molecules with potential anti-COVID-19 effects have been developed. So far, several antiviral strategies were explored. Besides directly inhibition of viral proteins such as RdRp and Mpro, interference of host enzymes including ACE2 and proteases, and blocking relevant immunoregulatory pathways represented by JAK/STAT, BTK, NF-κB, and NLRP3 pathways, are regarded feasible in drug development. The development of small molecules to treat COVID-19 has been achieved by several strategies, including computer-aided lead compound design and screening, natural product discovery, drug repurposing, and combination therapy. Several small molecules representative by remdesivir and paxlovid have been proved or authorized emergency use in many countries. And many candidates have entered clinical-trial stage. Nevertheless, due to the epidemiological features and variability issues of SARS-CoV-2, it is necessary to continue exploring novel strategies against COVID-19. This review discusses the current findings in the development of small molecules for COVID-19 treatment. Moreover, their detailed mechanism of action, chemical structures, and preclinical and clinical efficacies are discussed.

Despite passing the pandemic phase of the COVID-19, researchers are still investigating various drugs. Previous evidence suggests that blocking the calcium channels may be a suitable treatment option. Ca2+ is required to enhance the fusion process of Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Also, some important inflammatory factors during SARS-CoV-2 infection are dependent on Ca2+ level. On the other hand, viroporins have emerged as attractive targets for antiviral therapy due to their essential role in viral replication and pathogenesis. By inhibiting the host calcium channels and viroporins, it is possible to limit the spread of infection. Therefore, calcium channel blockers (CCBs) and drugs targeting Viroporins can be considered an effective option in the fight against SARS-CoV-2.

IntroductionWith the increasingly serious problem of antiviral drug resistance, drug repurposing offers a time-efficient and cost-effective way to find potential therapeutic agents for disease. Computational models have the ability to quickly predict potential reusable drug candidates to treat diseases.MethodsIn this study, two matrix decomposition-based methods, i.e., Matrix Decomposition with Heterogeneous Graph Inference (MDHGI) and Bounded Nuclear Norm Regularization (BNNR), were integrated to predict anti-viral drugs. Moreover, global leave-one-out cross-validation (LOOCV), local LOOCV, and 5-fold cross-validation were implemented to evaluate the performance of the proposed model based on datasets of DrugVirus that consist of 933 known associations between 175 drugs and 95 viruses.ResultsThe results showed that the area under the receiver operating characteristics curve (AUC) of global LOOCV and local LOOCV are 0.9035 and 0.8786, respectively. The average AUC and the standard deviation of the 5-fold cross-validation for DrugVirus datasets are 0.8856 ± 0.0032. We further implemented cross-validation based on MDAD and aBiofilm, respectively, to evaluate the performance of the model. In particle, MDAD (aBiofilm) dataset contains 2,470 (2,884) known associations between 1,373 (1,470) drugs and 173 (140) microbes. In addition, two types of case studies were carried out further to verify the effectiveness of the model based on the DrugVirus and MDAD datasets. The results of the case studies supported the effectiveness of MHBVDA in identifying potential virus-drug associations as well as predicting potential drugs for new microbes.

Abstract Background SARS-CoV-2 has caused a worldwide pandemic since December 2019 and the search for pharmaceutical targets against COVID-19 remains an important challenge. Here, we studied the envelope protein E of SARS-CoV and SARS-CoV-2, a highly conserved 75–76 amino acid viroporin that is crucial for virus assembly and release. E protein channels were recombinantly expressed in HEK293 cells, a membrane-directing signal peptide ensured transfer to the plasma membrane. Methods Viroporin channel activity of both E proteins was investigated using patch-clamp electrophysiology in combination with a cell viability assay. We verified inhibition by classical viroporin inhibitors amantadine, rimantadine and 5-(N,N-hexamethylene)-amiloride, and tested four ivermectin derivatives. Results Classical inhibitors showed potent activity in patch-clamp recordings and viability assays. In contrast, ivermectin and milbemycin inhibited the E channel in patch-clamp recordings but displayed only moderate activity on the E protein in the cell viability assay, which is also sensitive to general cytotoxic activity of the tested compounds. Nemadectin and ivermectin aglycon were inactive. All ivermectin derivatives were cytotoxic at concentrations > 5 µM, i.e. below the level required for E protein inhibition. Conclusions This study demonstrates direct inhibition of the SARS-CoV-2 E protein by classical viroporin inhibitors. Ivermectin and milbemycin inhibit the E protein channel but their cytotoxicity argues against clinical application.

AbstractSARS-CoV-2 has been responsible for the major worldwide pandemic of COVID-19. Despite the enormous success of vaccination campaigns, virus infections are still prevalent and effective antiviral therapies are urgently needed. Viroporins are essential for virus replication and release, and are thus promising therapeutic targets. Here, we studied the expression and function of recombinant ORF3a viroporin of SARS-CoV-2 using a combination of cell viability assays and patch-clamp electrophysiology. ORF3a was expressed in HEK293 cells and transport to the plasma membrane verified by a dot blot assay. Incorporation of a membrane-directing signal peptide increased plasma membrane expression. Cell viability tests were carried out to measure cell damage associated with ORF3a activity, and voltage-clamp recordings verified its channel activity. The classical viroporin inhibitors amantadine and rimantadine inhibited ORF3a channels. A series of ten flavonoids and polyphenolics were studied. Kaempferol, quercetin, epigallocatechin gallate, nobiletin, resveratrol and curcumin were ORF3a inhibitors, with IC50 values ranging between 1 and 6 µM, while 6-gingerol, apigenin, naringenin and genistein were inactive. For flavonoids, inhibitory activity could be related to the pattern of OH groups on the chromone ring system. Thus, the ORF3a viroporin of SARS-CoV-2 may indeed be a promising target for antiviral drugs.