Advantages of Drug Repurposing

Advantages of Drug Repurposing

By Shawn Watson, Head of Research and Development


What is Drug Repurposing?

Drug repurposing became a topic of conversation this past year when existing therapeutics like the anti-malaria drug chloroquine/hydroxychloroquine and remdesivir, initially developed to treat hepatitis C were both repurposed to treat SARS-CoV-2. In fact, more than 150 drugs that are presently being used or evaluated to treat coronavirus are indeed repositioned.1

Drug repurposing is the process of identifying new therapeutic use(s) for old/existing/available drugs. It is an effective strategy in discovering or developing drug molecules with new pharmacological/therapeutic indications.

The market for repurposed drugs was valued at $24.4 billion in 20152 and is expected to reach $35 billion by 20273. Additionally, the market generates around 25% of the annual revenue for the pharmaceutical industry.2 In addition to financial incentives, the rising popularity of repurposing can be attributed to other main benefits:

  • Reduced development timelines with an average savings of 5-7 years2;
  • Higher approval rates;
  • Sales potential: 25% to 40% of annual pharmaceutical revenues can be generated from the sales of repurposed drugs1;
  • Lower (50-60%) overall development costs estimated to be $300 million, compared to the $2-3 billion to bring a novel drug into the market1; and
  • Already approved medicines – and many discarded compounds – have been tested in humans so comprehensive information exists on their pharmacology, dose, possible toxicity, and formulation.
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Strategies to Assist Drug Repurposing

Although drug repurposing is not novel, it has become a significant part of the pharmaceutical industry, and can occur at various stages of drug development. In recent years, many pharmaceutical companies have developed new drugs by applying a drug repositioning strategy4:

Repurpose for rare diseases and unmet needs

Repurposing drugs to treat both common and rare diseases offers the advantage of working with de-risked compounds. Due to cost effectiveness and a reduced timeline, repurposing drugs for new indications represents a method for finding rare disease treatments that have advantages over traditional drug development. An example is Pfizer’s Rapamune® (sirolimus) that was approved to prevent organ transplant rejection, but also became the first approved drug for the rare genetic lung disease lymphagioleiomyomatosis.4

Repurpose within a disease indication

Drugs developed for one indication may have broadened applications within that particular disease state. For instance, oncology drugs originally developed for a type of cancer can be investigated in other similar tumor types to produce more versatile drugs. Consider Merck’s Keytruda® (pembrolizumab), first approved for melanoma is now approved for 14 cancer types.4

Repurpose across therapeutic areas

Pharma is also evaluating whether drugs approved for one indication have potential to treat patients in a different therapeutic area. For instance, Novartis’ Arzerra (ofatumumab) is a monoclonal antibody to treat chronic lymphocytic leukemia, but clinical studies are underway to determine its effectiveness to treat adults with relapsing forms of multiple sclerosis.4
Drug repurposing has been a common approach in Alzheimer’s drug therapies. Of the repurposed drugs in the Alzheimer’s pipeline, 20% are hematologic-oncologic agents, 18% are drugs derived from cardiovascular indications, 14% are agents with psychiatric uses, 12% are drugs used to treat diabetes, 10% are neurologic agents, and the remaining 26% of drugs fall under other conditions.5


Shorter Path to Approval

About one-third of the new drug Food & Drug Administration (FDA) approvals are repurposed drugs. Of the 28 drugs approved by the FDA in the first quarter of 2020, twelve were repurposed.1 According to the National Center for Advancing Translational Sciences (NCATS), repurposing builds upon previous research and development efforts, so new candidate therapies could be ready for clinical trials quickly, speeding their review by the FDA and integration into health care. NCATS offers financial support by way of research grants for drug repurposing and has dedicated resources for drug repositioning efforts.

A common step in repurposing is to screen libraries of already approved compounds against a disease-specific biological assay. From such screens, researchers can select a subset of bioactive compounds for further interrogation in secondary and tertiary assays evaluating relevant aspects of disease biology and molecular pathophysiology.

Drug candidates for repurposing may have the advantage of being submitted through a 505(b)(2). This pathway allows for the registration of a drug for which at least one of the studies relied upon for approval was not conducted by the applicant. Thus, applicants can partially rely on published literature and the FDA’s previous findings regarding safety of an approved product to supplement their data. Accordingly, fewer supporting studies are required, resulting in shorter timelines and reduced costs. Furthermore, to achieve the 505(b)(2) approval, drug developers must identify a unique administration route, or disease indication, for their repurposed drug compared with the primary route and indication.6


Where to Get Help

The process of drug repurposing does encounter scientific, financial, and regulatory challenges, including dosing and dosing regimen along with questions around efficacy with a new patient population. Working with a consultant or contract development and manufacturing organization (CDMO) with experience and expertise in developing an already approved drug for a new purpose can help overcome those challenges, streamline the process to advance a repurposed drug to market, and work to achieve strategic success.

In the last decade, the number of service providers that support drug developers in repurposing efforts has grown. As a result, outsourcing activity related to drug repurposing is anticipated to grow at a rate of 20-25%, reaching $1.2 billion in 2030.1 Look for contractors that can offer both active pharmaceutical ingredient (API) synthesis services and the ability to formulate those APIs into finished drugs. There is no question that the CDMO plays a significant role in drug repurposing and supporting the pharmaceutical industry in taking drugs to market approval.


Talk to a Pii Scientist


Pharmaceutics International, Inc. (Pii) is a US-based contract development and manufacturing organization (CDMO) located in Hunt Valley, Maryland. The experienced scientists, engineers, and staff at Pii pride themselves on adroitly employing a phase appropriate method of drug development for the prudent use of their client’s resources as they solve challenging problems. In addition to offering end-to-end development services, Pii manufactures a variety of dosage forms to include complex parenteral drugs and has a wealth of analytical testing capabilities. Its Hunt Valley campus has four aseptic suites with lyophilization capabilities. Our talented professionals stand ready to help!



Shawn Watson
Head of Research and Development

Shawn Watson joined Pii in July 2020 and is responsible for all product development, including sterile, non-sterile, oral, and topical dosage forms, as well as analytical methods development. He has additional responsibilities for the Quality Control and Microbiology Laboratories. 

Shawn has over twenty years of leadership experience in the pharmaceutical industry in specialty, generic and contract development and manufacturing organizations (CDMOs). His wealth of knowledge spans Research and Development, Quality, and Technical Services.

Prior to joining Pii, he served as the Vice President of Quality and Laboratory Operations at Lupin Pharmaceuticals, Vice President of Compliance at Sigmapharm Laboratories, and Supervisor of Analytical R&D at Teva Pharmaceuticals. Additionally, he has held a variety of other key positions including Vice President of Quality, Senior Director of Chemistry & Manufacturing services, and Senior Manager of Analytical Research and Development. Shawn’s passion for working in the pharmaceutical industry began with his very first job as a quality control chemist with a CDMO and included work with Pii.

Shawn earned a Masters of Business Administration from the Fox School of Business at Temple University, a Masters of Science in Chemistry from Villanova University, and a Bachelors of Science in Chemistry and Biology from Heidelberg University. He also obtained a six sigma green belt from Villanova University.