COVID-19 drug repurposing research

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Drug repositioning (also known as drug repurposing, re-profiling, re-tasking, or therapeutic switching) is the repurposing of an approved drug for the treatment of a different disease or medical condition than that for which it was originally developed.^[1] This is one line of scientific research which is being pursued to develop safe and effective COVID‑19 treatments.^[2][3] Other research directions include the development of a COVID‑19 vaccine^[4] and convalescent plasma transfusion.^[5]

Several existing antiviral medications, previously developed or used as treatments for severe acute respiratory syndrome (SARS), Middle East respiratory syndrome (MERS), HIV/AIDS, and malaria, have been researched as potential COVID‑19 treatments, with some moving into clinical trials.^[6][7][8]

In a statement to the journal Nature Biotechnology in February 2020, US National Institutes of Health Viral Ecology Unit chief Vincent Munster said, "The general genomic layout and the general replication kinetics and the biology of the MERS, SARS and [SARS-CoV-2] viruses are very similar, so testing drugs which target relatively generic parts of these coronaviruses is a logical step".^[2]

Background

Outbreaks of novel emerging infections such as COVID‑19 pose unique challenges to discover treatments appropriate for clinical use, given the small amount of time available for drug discovery.^[9] Since the process of developing and licensing a new drug for COVID‑19 was expected to pose a particularly long delay, researchers have been probing the existing compendium of approved antivirals and other drugs as a cost-effective strategy in the meantime.^[9] In early 2020 hundreds of hospitals and universities began their own trials of existing safe drugs with repurposing potential against COVID‑19.^[10]

Drug repurposing usually requires three steps before taking the drug across the development pipeline: recognition of the right drug; systematic evaluation of the drug effect in clinical models; and estimation of usefulness in phase II clinical trials.^[11]

One approach used in repositioning is to look for drugs that act through virus-related targets such as the RNA genome (i.e. remdesivir). Another approach concerns drugs acting through polypeptide packing (i.e. lopinavir).^[9]

The rush to publish papers about the pandemic resulted in some scandals of inaccurate scientific publications.^[12]

Monoclonal antibodies

Monoclonal antibodies under investigation for repurposing include anti-IL-6 agents (tocilizumab)^[13] and anti-IL-8 (BMS-986253).^[14] (This is in parallel to novel monoclonal antibody drugs developed specifically for COVID‑19.)

Mavrilimumab is a human monoclonal antibody that inhibits human granulocyte macrophage colony-stimulating factor receptor (GM-CSF-R).^[15][16] It has been studied to see if it can improve the prognosis for patients with COVID‑19 pneumonia and systemic hyperinflammation. One small study indicated some beneficial effects of treatment with mavrilimumab compared with those who were not.^[17]

In January 2021, the UK National Health Service issued guidance that the immune modulating drugs tocilizumab and sarilumab were beneficial when given promptly to people with COVID‑19 admitted to intensive care, following research which found a reduction in the risk of death by 24%.^[18]

Tocilizumab

Tocilizumab is an interleukin 6 inhibitor authorized for use in several conditions, including rheumatoid arthritis, giant cell arteritis, systemic juvenile idiopathic arthritis and severe cytokine release syndrome.^[19] Its use has been studied in a number of trials.^{[citation needed]}

Hoffmann–La Roche and the WHO have run separate trials in severe cases.^[20] Roche announced on 29 July 2020, that its randomized double-blind trial of tocilizumab for the treatment of pneumonia in Covid patients had shown no benefits.^[21]

The REMAP‑CAP study in the UK found that tocilizumab was beneficial in adults with severe COVID‑19, who were critically ill and receiving respiratory or cardiovascular organ support in an intensive care setting, when this was started within 24 hours of the need for organ support.^[19] The use of tocilizumab and its place in therapy have been updated by UK NICE in January 2021.^[19]

It has been part of the large RECOVERY Trial in the UK.^[13] The published results have been reviewed as the most definitive evidence addressing the controversy over whether tocilizumab should be included in treatment for severely ill patients with COVID‑19.^[22] Over 4000 adults were randomly assigned to tocilizumab or usual care, several times more than the total in previous randomised trials, and most patients received systemic corticosteroids. Mortality within 28 days was 31% in patients allocated to tocilizumab and 35% in those receiving usual care (rate ratio 0·85; p=0·0028). Discharge from the hospital within 28 days was also more likely.^[22]

In June 2021, the U.S. Food and Drug Administration (FDA) issued an emergency use authorization (EUA) for tocilizumab for the treatment of COVID‑19 in hospitalized people aged two years of age and older who are receiving systemic corticosteroids and require supplemental oxygen, non-invasive or invasive mechanical ventilation, or extracorporeal membrane oxygenation (ECMO).^[23][24][25]

As of August 2021, the European Medicines Agency (EMA) is evaluating tocilizumab to extend its use to include treatment of hospitalized adults with severe COVID‑19 who are already receiving treatment with corticosteroids and require extra oxygen or mechanical ventilation (breathing assisted by a machine).^[26]

Antivirals

Research is focused on repurposing approved antiviral drugs that have been previously developed against other viruses, such as MERS-CoV, SARS-CoV, and West Nile virus.^[27] These include favipiravir,^[27] remdesivir,^[28] ribavirin,^[29] triazavirin,^[30] and umifenovir.^[31]

The combination of artesunate/pyronaridine was found to have an inhibitory effect on SARS-CoV-2 in vitro tests using Hela cells. Artesunate/pyronaridine showed a virus titer inhibition rate of 99% or more after 24 hours, while cytotoxicity was also reduced.^[32] A preprint published in July 2020, reported that pyronaridine and artesunate exhibit antiviral activity against SARS-CoV-2 and influenza viruses using human lung epithelial (Calu-3) cells.^[33] It is in phase II clinical trial in South Korea^[34][35][36] and in South Africa.^[37]

GS-441524 is the nucleoside of the ProTide remdesivir. It has been shown to cure cats infected with Feline infectious peritonitis (FIP), a feline form of coronavirus with a 96% cure rate.^[38][39] Studies have shown that even when remdesivir is administered, GS-441524 is the predominant metabolite circulating in serum due to rapid hydrolysis of the remdesivir pro-drugs, followed by dephosphorylation.^{[40][41][42][43][unreliable medical source?]} Some researchers have suggested its utility as a treatment for COVID‑19,^{[40][44][45][46][47]} noting easier synthesis, lack of first-pass metabolism in the liver, greater hydrophilicity and triphosphate formation in cell types irrespective of expression CES1 and CTSA, the enzymes required to bioactivate remdesivir.

Molnupiravir is a drug developed to treat influenza. It is in Phase III trials as a treatment for COVID‑19.^{[48][49][50][51][52]} In December 2020, scientists reported that the antiviral drug molnupiravir developed for the treatment of influenza can completely suppress SARS-CoV-2 transmission within 24 hours in ferrets whose COVID‑19 transmission they find to closely resemble SARS-CoV-2 spread in human young-adult populations.^[53][54] A clinical trial, which has not as of 1 October 2021 been peer reviewed, suggests molnupiravir taken orally can reduce the risk of hospitalization and prevent death in patients diagnosed with COVID‑19. The drug needs to be given early to be effective.^[55][56]

Niclosamide was identified as a candidate antiviral in an in vitro drug screening assay done in South Korea.^[57]

Protease inhibitors, which specifically target the protease 3CLpro, are being researched and developed in the laboratory such as CLpro-1, GC376, and Rupintrivir.^[58][59][60]

Coronaviruses species possess an intrinsic resistance to ribavirin.^[61]

Favipiravir

Favipiravir is an antiviral drug approved for the treatment of influenza in Japan.^[62][27] There is limited evidence suggesting that, compared to other antiviral drugs, favipiravir might improve outcomes for people with COVID‑19, but more rigorous studies are needed before any conclusions can be drawn.^[63]

Chinese clinical trials in Wuhan and Shenzhen claimed to show that favipiravir was "clearly effective".^[64] Of 35 patients in Shenzhen tested negative in a median of 4 days, while the length of illness was 11 days in the 45 patients who did not receive it.^[65] In a study conducted in Wuhan on 240 patients with pneumonia half were given favipiravir and half received umifenovir. The researchers found that patients recovered from coughs and fevers faster when treated with favipiravir, but that there was no change in how many patients in each group progressed to more advanced stages of illness that required treatment with a ventilator.^[66]

On 22 March 2020, Italy approved the drug for experimental use against COVID‑19 and began conducting trials in the three regions most affected by the disease.^[67] The Italian Pharmaceutical Agency reminded the public that the existing evidence in support of the drug is scant and preliminary.^[68]

On 30 May 2020, the Russian Health Ministry approved a generic version of favipiravir named Avifavir, which proved highly effective in the first phase of clinical trials.^[69][70][71]

In June 2020, India approved the use of a generic version of favipravir called FabiFlu, developed by Glenmark Pharmaceuticals, in the treatment of mild to moderate cases of COVID‑19.^[72]

On 26 May 2021, a systematic review found a 24% greater chance of clinical improvement when administered in the first seven days of hospitalization, but no statistically significant reduction in mortality for any of the groups, including hospitalized patients and those with mild or moderate symptoms.^[73][74]

Lopinavir/ritonavir

Genome of SARS-CoV-2: the grey wedges show where 3CLpro the main coronavirus protease cleaves the polyprotein.

In March 2020, the main protease (3CLpro) of the SARS-CoV-2 virus was identified as a target for post-infection drugs. The enzyme is essential for processing the replication-related polyprotein. To find the enzyme, scientists used the genome published by Chinese researchers in January 2020 to isolate the main protease.^[75] Protease inhibitors approved for treating human immunodeficiency viruses (HIV) – lopinavir and ritonavir – have preliminary evidence of activity against the coronaviruses, SARS and MERS.^[6][76] As a potential combination therapy, they are used together in two Phase III arms of the 2020 global Solidarity project on COVID‑19.^[76][77] A preliminary study in China of combined lopinavir and ritonavir found no effect in people hospitalized for COVID‑19.^[78]

One study of lopinavir/ritonavir (Kaletra), a combination of the antivirals lopinavir and ritonavir, concluded that "no benefit was observed".^[78][79] The drugs were designed to inhibit HIV from replicating by binding to the protease. A team of researchers at the University of Colorado are trying to modify the drugs to find a compound that will bind with the protease of SARS-CoV-2.^[80] There are criticisms within the scientific community about directing resources to repurposing drugs specifically developed for HIV/AIDS because such drugs are unlikely to be effective against a virus lacking the specific HIV-1 protease they target.^[2] The WHO included lopinavir/ritonavir in the international Solidarity trial.^[81]

On 29 June, the chief investigators of the UK RECOVERY Trial reported that there was no clinical benefit from use of lopinavir-ritonavir in 1,596 people hospitalized with severe COVID‑19 infection over 28 days of treatment.^[82][83]

A study published in October 2020, screening those FDA approved drugs which target SARS-CoV-2 spike (S) protein proposed that the current unbalanced combination formula of lopinavir might in fact interfere with the ritonavir's blocking activity on the receptor binding domain-human angiotensin converting enzyme-2 (RBD-hACE2) interaction, thus effectively limiting its therapeutic benefit in COVID‑19 cases.^[84]

Remdesivir

This section is an excerpt from Remdesivir.[]

Remdesivir, sold under the brand name Veklury,^[85][86] is a broad-spectrum antiviral medication developed by the biopharmaceutical company Gilead Sciences.^[87] It is administered via injection into a vein.^[88][89] During the COVID-19 pandemic, remdesivir was approved or authorized for emergency use to treat COVID‑19 in around 50 countries.^[90] Updated guidelines from the World Health Organization in November 2020 include a conditional recommendation against the use of remdesivir for the treatment of COVID-19.^[91]

Remdesivir was originally developed to treat hepatitis C,^[92] and was subsequently investigated for Ebola virus disease and Marburg virus infections^[93] before being studied as a post-infection treatment for COVID-19.^[94]

Remdesivir is a prodrug that is intended to allow intracellular delivery of GS-441524 monophosphate and subsequent biotransformation into GS-441524 triphosphate, a ribonucleotide analogue inhibitor of viral RNA polymerase.^[95]

The most common side effect in healthy volunteers is raised blood levels of liver enzymes.^[85] The most common side effect in people with COVID‑19 is nausea.^[85] Side effects may include liver inflammation and an infusion-related reaction with nausea, low blood pressure, and sweating.^[96]

The U.S. Food and Drug Administration (FDA) considers it to be a first-in-class medication.^[97]

Antiparasitics

The idea of repurposing host-directed drugs for antiviral therapy has experienced a renaissance.^[98] In some cases the research has highlighted fundamental limitations to their use for the treatment of acute RNA virus infections.^[99] Antiparasitics that have been investigated include chloroquine,^[100] hydroxychloroquine,^[101] mefloquine,^[102][103] ivermectin,^[104] and atovaquone.^[105]

Chloroquine and hydroxychloroquine

This section is an excerpt from Chloroquine and hydroxychloroquine during the COVID-19 pandemic.[]

A World Health Organization infographic stated that hydroxychloroquine does not prevent illness or death from COVID-19.

Chloroquine and hydroxychloroquine are anti-malarial medications also used against some auto-immune diseases.^[106] Chloroquine, along with hydroxychloroquine, was an early experimental treatment for COVID-19.^[107] Neither drug prevents SARS-CoV-2 infection.^{[108][109][110][111][112]}

Cleavage of the SARS-CoV-2 S2 spike protein required for viral entry into cells can be accomplished by proteases TMPRSS2 located on the cell membrane, or by cathepsins (primarily cathepsin L) in endolysosomes.^[113] Hydroxychloroquine inhibits the action of cathepsin L in endolysosomes, but because cathepsin L cleavage is minor compared to TMPRSS2 cleavage, hydroxychloroquine does little to inhibit SARS-CoV-2 infection.^[113]

Several countries initially used chloroquine or hydroxychloroquine for treatment of persons hospitalized with COVID‑19 (as of March 2020), though the drug was not formally approved through clinical trials.^[114][115] From April to June 2020, there was an emergency use authorization for their use in the United States,^[116] and was used off label for potential treatment of the disease.^[117] On 24 April 2020, citing the risk of "serious heart rhythm problems", the FDA posted a caution against using the drug for COVID‑19 "outside of the hospital setting or a clinical trial".^[118]

Their use was withdrawn as a possible treatment for COVID‑19 infection when it proved to have no benefit for hospitalized patients with severe COVID-19 illness in the international Solidarity trial and UK RECOVERY Trial.^[119][120] On 15 June, the FDA revoked its emergency use authorization, stating that it was "no longer reasonable to believe" that the drug was effective against COVID-19 or that its benefits outweighed "known and potential risks".^{[121][122][123]} In fall of 2020, the National Institutes of Health issued treatment guidelines recommending against the use of hydroxychloroquine for COVID-19 except as part of a clinical trial.^[106]

In 2021, hydroxychloroquine was part of the recommended treatment for mild cases in India.^[124]

Ivermectin

Anticoagulants

Medications to prevent blood clotting have been suggested for treatment, and anticoagulant therapy with low-molecular-weight heparin appears to be associated with better outcomes in severe COVID‐19 showing signs of coagulopathy (elevated D-dimer).^[130] Several anticoagulants have been tested in Italy, with low-molecular-weight heparin being widely used to treat patients, prompting the Italian Medicines Agency to publish guidelines on its use.^[131][132]

Scientists have identified an ability of heparin to bind to the spike protein of the SARS-CoV-2 virus, neutralising it, and proposed the drug as a possible antiviral.^[133]

A multicenter study on 300 patients researching the use of enoxaparin sodium at prophylaxis and therapeutic dosages was announced in Italy on 14 April.^[134]

The anticoagulant dipyridamole is proposed as a treatment for COVID‑19,^[135] and a clinical trial is underway.^[136]

Immunosuppressants

As of July 2021, the European Medicines Agency (EMA) is evaluating an application to extend the use of anakinra (Kineret) to include treatment of COVID‑19 in adults with pneumonia who are at risk of developing severe respiratory failure (inability of the lungs to work properly).^[137]

Interferons

Drugs with immune modulating effects that may prove useful in COVID‑19 treatment include type I Interferons such as Interferon-β, peginterferon alpha-2a and -2b.^[138][139]

IFN-β 1b have been shown in an open label randomised controlled trial in combination with lopinavir/ ritonavir and ribavirin to significantly reduce viral load, alleviate symptoms and reduce cytokine responses when compared to lopinavir/ ritonavir alone.<Lancet 2020;395(10238):1695-1704> IFN-β will be included in the international Solidarity Trial in combination with the HIV drugs Lopinavir and Ritonavir.^[138] as well as the REMAP-CAP^[139] Finnish biotech firm Faron Pharmaceuticals continues to develop INF-beta for ARDS and is involved in worldwide initiatives^[which?] against COVID‑19, including the Solidarity trial.^[140] UK biotech firm Synairgen started conducting trials on IFN-β, a drug that was originally developed to treat COPD.^[81]

Steroids

Dexamethasone

A vial of dexamethasone for injection

Dexamethasone is a corticosteroid medication in use for multiple conditions such as rheumatic problems, skin diseases, asthma and chronic obstructive lung disease among others.^[141] A multi-center, randomized controlled trial of dexamethasone in treating acute respiratory distress syndrome (ARDS), published in February 2020, showed reduced need for mechanical ventilation and mortality.^[142] Dexamethasone is only helpful in people requiring supplemental oxygen. Following an analysis of seven randomized trials,^[143] the WHO recommends the use of systemic corticosteroids in guidelines for treatment of people with severe or critical illness, and that they not be used in people that do not meet the criteria for severe illness.^[144]

On 16 June, the Oxford University RECOVERY Trial issued a press release announcing preliminary results that the drug could reduce deaths by about a third in participants on ventilators and by about a fifth in participants on oxygen; it did not benefit patients who did not require respiratory support. The researchers estimated that treating 8 patients on ventilators with dexamethasone saved one life, and treating 25 patients on oxygen saved one life.^[145] Several experts called for the full dataset to be published quickly to allow wider analysis of the results.^[146][147] A preprint was published on 22 June^[148] and the peer-reviewed article appeared on 17 July.^[149]

Based on those preliminary results, dexamethasone treatment has been recommended by the US National Institutes of Health (NIH) for patients with COVID‑19 who are mechanically ventilated or who require supplemental oxygen but are not mechanically ventilated. The NIH recommends against using dexamethasone in patients with COVID‑19 who do not require supplemental oxygen.^[150] In July 2020, the World Health Organization (WHO) stated they are in the process of updating treatment guidelines to include dexamethasone or other steroids.^[151]

The Infectious Diseases Society of America (IDSA) guideline panel suggests the use of glucocorticoids for patients with severe COVID‑19; where severe is defined as patients with oxygen saturation (SpO₂) ≤94% on room air, and those who require supplemental oxygen, mechanical ventilation, or extracorporeal membrane oxygenation (ECMO).^[152] The IDSA recommends against the use of glucocorticoids for those with COVID‑19 without hypoxemia requiring supplemental oxygen.^[152]

In July 2020, the European Medicines Agency (EMA) started reviewing results from the RECOVERY study arm that involved the use of dexamethasone in the treatment of patients with COVID‑19 admitted to the hospital to provide an opinion on the results. It focused particularly on the potential use of the drug for the treatment of adults with COVID‑19.^[153]

In September 2020, the WHO released updated guidance on using corticosteroids for COVID‑19.^[154] The WHO recommends systemic corticosteroids rather than no systemic corticosteroids for the treatment of people with severe and critical COVID‑19 (strong recommendation, based on moderate certainty evidence).^[154] The WHO suggests not to use corticosteroids in the treatment of people with non-severe COVID‑19 (conditional recommendation, based on low certainty evidence).^[154]

In September 2020, the European Medicines Agency (EMA) endorsed the use of dexamethasone in adults and adolescents (from twelve years of age and weighing at least 40 kilograms (88 lb)) who require supplemental oxygen therapy.^[155] Dexamethasone can be taken by mouth or given as an injection or infusion (drip) into a vein.^[155]

Hydrocortisone

In September 2020, a meta-analysis published by the WHO Rapid Evidence Appraisal for COVID‑19 Therapies (REACT) Working Group found hydrocortisone to be effective in reducing mortality rate of critically ill COVID‑19 patients when compared to other usual care or a placebo.^[156]

The use of corticosteroids can cause a severe and deadly "hyperinfection" syndrome for people with strongyloidiasis, which may be an underlying condition in populations exposed to the parasite Strongyloides stercoralis. This risk can be mitigated by the presumptive use of ivermectin before steroid treatment.^[157]

Budesonide

Administration of this inhaled steroid early in the course of COVID‑19 infection has been found to reduce the likelihood of needing urgent medical care and reduced the time to recovery.^[158][159] More studies are on-going.^[159] In April 2021, budesonide was approved by authorities in the UK for off-label use to treat COVID‑19 on a case-by-case basis.^[160]

Others

Ciclesonide, an inhaled corticosteroid for asthma, was identified as a candidate antiviral in an in vitro drug screening assay done in South Korea.^[57] It has been used for treatment of pre-symptomatic COVID‑19 patients and is under-going clinical trials.^[161]

Antidepressants

Many antidepressants have anti-inflammatory properties. An observational study in Paris area hospitals found that COVID-19 patients admitted to the hospital who were already taking an antidepressant had 44% less risk of intubation or death.^[162][163]

Fluvoxamine

In October 2021, a large clinical trial in Brazil reported that treating high-risk outpatients with an early diagnosis of COVID-19 with 100 mg fluvoxamine twice daily for 10 days reduced by up to about 65% the risk of hospitalization. The effect was reduced to about 32% with low adherence, possibly due to intolerance. There was also a reduction in the number of deaths by up to about 90% with high adherence. The drug was studied because of its anti-inflammatory effects, but the mechanism of action against COVID-19 remains uncertain.^{[164][165][166]}

Vitamins

Vitamin C

Supplementation with micronutrients, including vitamin C, has been suggested as part of the supportive management of COVID‑19, as levels of vitamin C in serum and leukocytes are depleted in the acute stage of infection owing to increased metabolic demands.^[167] The use of high-dose intravenous vitamin C has been studied.^[167] According to ClinicalTrials.gov, there are 50 completed or ongoing clinical trials including vitamin C, which have completed or are recruiting people, hospitalized and severely ill with COVID‑19.^[168]

A meta-analysis of six randomized clinical trials involving vitamin C treatments, using doses ranging from 50 mg/kg/day to 24 g/day given orally or intravenously, reported outcomes on mortality, hospitalization duration, intensive care duration and need for ventilation.^[169] This concluded that administration of vitamin C did not have any effect on major health outcomes in COVID-infected patients when compared to placebo or standard therapy. Sub-group analyses based on dosage, route of administration and disease severity, failed to show any observable benefits of vitamin C.^[169]

The National Institutes of Health (NIH) COVID‑19 Treatment Guidelines states "there is insufficient evidence for the COVID‑19 Treatment Guidelines Panel (the Panel) to recommend either for or against the use of vitamin C for the treatment of COVID‑19 in either critically ill or non-critically ill patients."^[170]

Vitamin D

Oral vitamin D tablets

During the COVID‑19 pandemic, there has been interest in vitamin D status and supplements, given the significant overlap in the risk factors for severe COVID‑19 and vitamin D deficiency.^[171] These include obesity, older age, and Black or Asian ethnic origin, and it is notable that vitamin D deficiency is particularly common within these groups.^[171]

The National Institutes of Health (NIH) COVID‑19 Treatment Guidelines states "there is insufficient evidence to recommend either for or against the use of vitamin D for the prevention or treatment of COVID‑19."^[172]

The general recommendation to consider taking vitamin D supplements, particularly given the levels of vitamin D deficiency in Western populations, has been repeated.^[173] As of February 2021, the English National Institute for Health and Care Excellence (NICE) continued to recommend small doses of supplementary vitamin D for people with little exposure to sunshine, but recommended that practitioners should not offer a vitamin D supplement solely to prevent or treat COVID‑19, except as part of a clinical trial.^[173]

Multiple studies have reported links between pre-existing vitamin D deficiency and the severity of the disease. Several systematic reviews and meta-analyses of these show that vitamin D deficiency may be associated with a higher probability of becoming infected with COVID‑19, and have clearly demonstrated there are significant associations between deficiency and a greater severity of the disease, including relative increases in hospitalization and mortality rates of about 80%.^{[174][175][176]} The quality of some of the studies included and whether this demonstrates a causal relationship has been questioned.^[177]

Many clinical trials are underway or have been completed assessing the use of oral vitamin D and its metabolites such as calcifediol for prevention or treatment of COVID‑19 infection, especially in people with vitamin D deficiency.^{[178][179][171][180]}

The effects of oral vitamin D supplementation on the need for intensive care unit (ICU) admission and mortality in hospitalized COVID‑19 patients has been the subject of a meta-analysis.^[181] A much lower ICU admission rate was found in patients who received vitamin D supplementation, which was only 36% of that seen in patients without supplementation (p<0.0001).^[181] No significant effects on mortality were found in this meta-analysis.^[181] The certainty of these analyses is limited by the heterogenicity in the studies which include both vitamin D3 (cholecalciferol) and calcifediol, but these findings indicate a potential role in improving COVID‑19 severity, with more robust data being required to substantiate any effects on mortality.^[181][182]

Calcifediol, which is 25-hydroxyvitamin D, is more quickly activated,^[183] and has been used in several trials.^[179] Review of the published results suggests that calcifediol supplementation may have a protective effect on the risk of ICU admissions in COVID‑19 patients.^[177]

Minerals

Zinc

The National Institutes of Health (NIH) COVID‑19 Treatment Guidelines states "there is insufficient evidence to recommend either for or against the use of zinc for the treatment of COVID‑19" and that "the Panel recommends against using zinc supplementation above the recommended dietary allowance for the prevention of COVID-19, except in a clinical trial (BIII)."^[184]

Others

A form of angiotensin-converting enzyme 2, a Phase II trial is underway with 200 patients to be recruited from severe, hospitalized cases in Denmark, Germany, and Austria to determine the effectiveness of the treatment.^[185][186]

Some antibiotics that have been identified as potentially repurposable as COVID‑19 treatments,^[187][188] including teicoplanin,^[189] oritavancin,^[190] dalbavancin,^[190] monensin,^[190] and azithromycin.^[191] New York State began trials for the antibiotic azithromycin on 24 March 2020.^[191]

On 31 July 2020, the U.S. Food and Drug Administration (FDA) authorized to proceed with a randomized, double-blind, placebo-controlled confirmatory Phase III clinical trial protocol to evaluate the safety and efficacy of the antirheumatic agent bucillamine in patients with mild-moderate COVID‑19.^[192]

The oral JAK inhibitor baricitinib is also being studied for COVID‑19 treatment.^[193] In November 2020, the FDA granted emergency use authorization for baricitinib to be given to certain people hospitalized with suspected or confirmed COVID‑19 (specifically, adults and children two years of age or older requiring supplemental oxygen, mechanical ventilation, or ECMO), but only in conjunction with remdesivir.^[194] In a single clinical trial, this combination therapy was shown to have a small, but statistically significant effect on patient outcomes compared to administration of remdesivir alone.^[195] In April 2021, the European Medicines Agency (EMA) started evaluating the extended use of baricitinib to include treatment of COVID‑19 in hospitalized patients ten years of age and older who require supplemental oxygen.^[196] In July 2021, the FDA revised the EUA for baricitinib now authorizing it alone for the treatment of COVID‑19 in hospitalized people aged two years of age or older requiring supplemental oxygen, non-invasive or invasive mechanical ventilation, or extracorporeal membrane oxygenation (ECMO).^{[197][198][199]} Under the revised EUA, baricitinib is no longer required to be administered with remdesivir.^[199]

In 2021, the importance of drug repurposing for COVID‑19 led to the establishment of broad-spectrum therapeutics.^[200] Broad-spectrum therapeutics are effective against multiple types of pathogens.^[201] Such drugs have been suggested as potential emergency treatments for future pandemics.^[202][203]

Histamine H₂ receptor antagonists are under investigation. Cimetidine has been suggested as a treatment for COVID‑19.^[135] Famotidine has been suggested as a treatment for COVID‑19,^[135] and a clinical study is underway.^[204]

Researchers from the Montreal Heart Institute in Canada are studying the role of colchicine in reducing inflammation and pulmonary complications in patients suffering from mild symptoms of COVID‑19.^[205] The study, named COLCORONA, was recruiting 6000 adults 40 and older who were diagnosed with COVID‑19 and experienced mild symptoms not requiring hospitalization.^[205][206] Women who were pregnant or breastfeeding or who did not have an effective contraceptive method were not eligible. The trial results are favorable, but inconclusive.^[206]

Fenofibrate and bezafibrate have been suggested for treatment of life-threatening symptoms of COVID‑19.^[135][207] Fenofibrate also lowered severe progressive inflammation markers in hospitalized COVID‑19 patients within 48 hours of treatment in an Israeli study.^[208] It showed extremely promising results by interfering with how coronavirus reproduce.^[209]

A trial called "Liberate" has been started in the United Kingdom to determine the effectiveness of ibuprofen in reducing the severity and progression of lung injury which results in breathing difficulties for COVID‑19 patients. Subjects are to receive three doses of a special formulation of the drug – lipid ibuprofen – in addition to usual care.^[210][211]

A clinical cohort study in Brazil found that COVID‑19 patients who received a recent influenza vaccine needed less intensive care support, less invasive respiratory support, and were less likely to die.^{[212][unreliable medical source?]}

nanoFenretinide is nanoparticle sized fenretinide and repurposed oncology drug approved to enter the clinic for a lymphoma indication.^[213] It was identified as a candidate antiviral in an in vitro drug screening assay done in South Korea.^[57] Fenretinide's clinical safety profile also makes it an ideal candidate in combination regimens.^{[citation needed]}

Sildenafil, more commonly known by the brand name Viagra, is proposed as a treatment for COVID‑19,^[135] and a Phase III clinical trial is underway.^[214]

References

Further reading

• Banday AH, Shameem SA, Ajaz SJ (2020). "Potential Repurposed Therapeutics and New Vaccines against COVID-19 and Their Clinical Status". SLAS Discov. 25 (10): 1097–107. doi:10.1177/2472555220945281. PMID 32692266. S2CID 220671335.CS1 maint: multiple names: authors list (link)
• Cantini F, Goletti D, Petrone L, Najafi Fard S, Niccoli L, Foti R (October 2020). "Immune Therapy, or Antiviral Therapy, or Both for COVID-19: A Systematic Review". Drugs. 80 (18): 1929–46. doi:10.1007/s40265-020-01421-w. PMC 7568461. PMID 33068263.
• Gordon DE, Jang GM, Bouhaddou M, Xu J, Obernier K, White KM, et al. (July 2020). "A SARS-CoV-2 protein interaction map reveals targets for drug repurposing". Nature. 583 (7816): 459–68. Bibcode:2020Natur.583..459G. doi:10.1038/s41586-020-2286-9. PMC 7431030. PMID 32353859.
• Guy RK, DiPaola RS, Romanelli F, Dutch RE (May 2020). "Rapid repurposing of drugs for COVID-19". Science. 368 (6493): 829–30. Bibcode:2020Sci...368..829G. doi:10.1126/science.abb9332. PMID 32385101.
• Kotecha P, Light A, Checcucci E, Amparore D, Fiori C, Porpiglia F, et al. (October 2020). "Repurposing of drugs for Covid-19: a systematic review and meta-analysis". Panminerva Med. doi:10.23736/S0031-0808.20.04024-0. PMID 33073552.
• Lamontagne F, Agoritsas T, Siemieniuk R, Rochwerg B, Bartoszko J, Askie L, et al. (2 March 2021). "A living WHO guideline on drugs to prevent covid-19". British Medical Journal. 372: n526. doi:10.1136/bmj.n526. PMID 33649077. S2CID 232081225.
• McCreary EK, Pogue JM (April 2020). "Coronavirus Disease 2019 Treatment: A Review of Early and Emerging Options". Open Forum Infectious Diseases. 7 (4): ofaa105. doi:10.1093/ofid/ofaa105. PMC 7144823. PMID 32284951.
• Siemieniuk RA, Bartoszko JJ, Ge L, Zeraatkar D, Izcovich A, Kum E, et al. (July 2020). "Drug treatments for covid-19: living systematic review and network meta-analysis". BMJ. 370: m2980. doi:10.1136/bmj.m2980. PMC 7390912. PMID 32732190.
• Velasquez-Manoff M (11 August 2020). "How Covid Sends Some Bodies to War With Themselves". The New York Times.
• Zimmer C (30 April 2020). "Old Drugs May Find a New Purpose: Fighting the Coronavirus". The New York Times.

External links

• "COVID-19 therapeutics tracker". Regulatory Affairs Professionals Society.
• "STAT's Covid-19 Drugs and Vaccines Tracker". Stat. 27 April 2020.
• "Coronavirus Drug and Treatment Tracker". The New York Times.
• "JHMI Clinical Recommendations for Available Pharmacologic Therapies for COVID-19". Johns Hopkins.
• World Health Organization (2021). Therapeutics and COVID-19: living guideline, 24 September 2021 (Report). World Health Organization (WHO). hdl:10665/345356. WHO/2019-nCoV/therapeutics/2021.3. Lay summary.