Use of repurposed drugs in COVID-19 pandemic: Old drugs without new tricks?

Suraj Kapoor

doi:10.4103/jphpc.jphpc_12_22

REVIEW ARTICLE

Year : 2023 | Volume : 4 | Issue : 1 | Page : 4-7

Use of repurposed drugs in COVID-19 pandemic: Old drugs without new tricks?

Suraj Kapoor
Department of Community Medicine, Armed Forces Medical College, Pune, Maharashtra, India

Date of Submission	05-Apr-2022
Date of Decision	07-May-2022
Date of Acceptance	08-May-2022
Date of Web Publication	19-Oct-2022

Correspondence Address:
Dr. Suraj Kapoor
Department of Community Medicine, Armed Forces Medical College, Solapur Road, Wanowrie, Pune - 411 040, Maharashtra
India

Source of Support: None, Conflict of Interest: None

DOI: 10.4103/jphpc.jphpc_12_22

Abstract

Traditional drug development and discovery have not kept speed with warnings from emerging and re-emerging diseases such as Zika, Nipah, Ebola virus, MERS-CoV, and more newly the pandemic of COVID-19. The new drug discovery has a limitation of high attrition rates, substantial costs, and longer duration for discovery, so repurposing old drugs to treat the diseases becomes a popular and feasible proposition. In contrast, repurposed drugs may be beneficial for patients in a time of pandemics when the natural history of the disease remains unclear. It may be beneficial for the manufacturers as well to generate additional revenues. The use of repurposed drugs in primary care saves money as well as time, particularly important in pandemic times, which can be a cost-effective measure in the public health aspect. Review of literature was carried out about the repurposed drugs used in the COVID-19 pandemic using health bulletins, official handles of health ministries, WHO, published literature, etc. The use of repurposed drugs is beneficial, particularly in pandemic and rare diseases, but their use should be taken with due caution and thorough evaluation. Important public health aspect in primary care includes avoidance of unnecessary hoarding of such drugs. International collaboration in assessing the effectiveness of repurposed drugs is suggested.

Keywords: Clinical trials, COVID-19, pandemic, repurposed drugs

How to cite this article:
Kapoor S. Use of repurposed drugs in COVID-19 pandemic: Old drugs without new tricks?. J Public Health Prim Care 2023;4:4-7

How to cite this URL:
Kapoor S. Use of repurposed drugs in COVID-19 pandemic: Old drugs without new tricks?. J Public Health Prim Care [serial online] 2023 [cited 2023 Jun 5];4:4-7. Available from: http://www.jphpc.org/text.asp?2023/4/1/4/358584

Introduction

With the advancement of scientific knowledge, new drugs are discovered, usually specific to diseases with detailed clinical trials. Preclinical trials involving animal studies are usually carried out, followed by human studies which include Phase 1 (safety), Phase 2 (safety and effectiveness), Phase 3 (randomized control trial), and Phase 4 (postmarketing surveillance) which is highlighted in [Figure 1].

Figure 1: Phases of clinical trial. FDA: Food and Drug Administration

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Repurposing of drugs can be defined as a process of identification of new pharmacological indications from old/prevailing/unsuccessful/untried/already marketed/Food and Drug Administration approved drugs/prodrugs and the application of the newly developed drugs to the treatment of diseases other than the drug's original/intended therapeutic use. It involves instituting new therapeutic applications for already existing drugs, including approved, discontinued, abandoned, and experimental drugs.^[1],[2]

Traditional drug development and discovery have not kept speed with warnings from emerging and re-emerging diseases such as Zika, Nipah, Ebola virus, MERS-CoV, and more newly the pandemic of COVID-19. The new drug discovery has a limitation of high attrition rates, substantial costs, and longer duration for discovery, so repurposing old drugs to treat the diseases becomes a popular and feasible proposition.^[3] In contrast, repurposed drugs may be beneficial for patients in a time of pandemics when the natural history of the disease remains unclear. It may be beneficial for the manufacturers as well to generate additional revenues. Due to these reasons, drug manufacturers are considering drug repurposing (or repositioning) as a feasible option for the more conventional drug development process to find alternative uses for an approved or investigational drug outside of its original indication. The use of repurposed drugs in primary care saves money as well as time, particularly important in pandemic times, which can be a cost-effective measure in the public health aspect. The present review highlights the use and application of repurposed drugs in the present pandemic.

Methods

Review of literature was carried out about the repurposed drugs used in the COVID-19 pandemic using health bulletins, official handles of health ministries, WHO, published literature, etc. The various repurposed drugs used during the pandemic times are compiled and discussed in [Table 1]. The relevance, limitations, and future perspective of repurposed drugs are highlighted in the study.

Table 1: Common repurposed drugs used in the COVID-19 pandemic

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Discussion

Use of repurposed drugs in COVID-19

The COVID-19 vaccination drive has been rolled out globally, but still, the effective treatment for the disease needs to be identified, particularly important in the settings of countries with low vaccine uptake. Furthermore, new variants of concern result in vaccine escape mechanisms. With the urgency of the pandemic, the repurposing of drugs seems to be an efficient strategy with already approved indications and safety profiles tested as compared to the discovery of new drugs.^[15] Multiple drugs are used as repurposing drugs in COVID-19. Some of the drug's description is highlighted in [Table 1]. Out of the various drugs listed in the table, steroids, particularly dexamethasone, and to a lesser extent, tocilizumab is the only drugs found to be effective.^[16]

Are repurpose drugs effective in COVID-19?

Many new drugs and repurposed drugs are used in the COVID-19 with many new novels as well as repurposed drugs in the pipeline. In pandemic times, the hit and trial of the drugs may only be the possible solution. Some repurposed drugs with a lack of effectiveness have been used widely; almost one in three patients globally have received hydroxychloroquine, despite only 1 of 18 randomized trials showing benefit.^[3] This is particularly important in the primary care context during the pandemic in which we witnessed hoarding and black marketing of certain drugs without proven effectiveness. However, before concluding the effectiveness of repurposed drugs, as highlighted in [Table 1], there should be thorough pharmacodynamic, pharmacokinetic, and pharmacogenomic. There can be drug–drug interactions, particularly important for drugs having the same metabolizing enzymes. Moreover, multiple unknown genomic factors might influence the outcome. At present, conflicting evidence exists regarding the effectiveness of the various repurposed drug used in the present pandemic, which necessitates a thorough evaluation of all the drugs used before the conclusion which might help in exploring the definitive treatment against the disease.

Relevance/limitations of repurposed drugs in primary care

Repurposing generic drugs could offer a cheaper and faster way to develop new treatments. Although repurposed drugs are cost-effective and time-saving in pandemic times, their use should be taken with caution. Moreover, unnecessary hoarding/black marketing of such drugs should be avoided as it may adversely impact the public health infrastructure, especially during pandemic times.

Drug repurposing faces the challenge of the intellectual property barrier. Repurposing is most available with generic drugs that do not have patents limiting their use for other conditions. Because of perceived lack of commercial potential, drug repurposing is normally left to academic organizations that do not have the resources to get either new or retooled drugs through the costly approval process. Moreover, various data-driven and experimental approaches have been recommended for the identification of repurposable drug candidates; however, there are also major technological and regulatory challenges that need to be addressed.^[15]

It is suggested that a thorough evaluation of repurposed drugs should be carried out to reveal scientific conclusions about them. It is also recommended that there should be international collaboration in the form of central data about the repurposed drug's effectiveness to have a final and scientific conclusion. Irrespective of how researchers decide which drugs to repurpose, all candidates must demonstrate strong clinical benefits in people before they can be authorized or approved. A thorough considerate of the current condition of the COVID-19 pandemic, the repurposed drugs and their toxicities as well as the various vaccine candidates is necessary to accelerate the research for the development of a novel anti-SARS-CoV-2 drug and an efficient vaccine.^[17] This will ultimately benefit inefficient combating the present pandemic as well-drafting policies and guidelines about the use of repurposed drugs.

Conclusion

The use of repurposed drugs is beneficial, particularly in pandemic and rare diseases, but their use should be taken with due caution and thorough evaluation. Important public health aspect in primary care includes avoidance of unnecessary hoarding of such drugs. International collaboration in assessing the effectiveness of repurposed drugs is suggested. Health policymakers and government officials should have strict vigilance about the use and sale of repurposed drugs with appropriate funding to assess the effectiveness of such drugs.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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