Medication Repurposing: New Uses for Old Drugs

Abstract

Background: Medication repurposing, the practice of using old drugs in new ways, is becoming more common. Old drugs that had previously fallen out of favor due to safety concerns, lack of efficacy, or development of more desirable therapeutic alternatives have been resurfacing in the literature and on pharmacy shelves. Developing new uses for old drugs may provide patients with access to helpful therapies but may also present challenges and risks. Objective: To explore the rationale for, and historical context of, the developing trend of recycling existing drugs for new, innovative uses, and to provide pharmacy practitioners with information about how to find clinical evidence regarding these new uses. Data Synthesis: The process of obtaining marketing approval for new drugs can take an average of over 10 years and exceed $1 billion. Repurposing old drugs (both approved and unapproved) for new uses requires considerably fewer resources since information about production needs, pharmacology, and pharmacokinetics is already known. Other advantages of using old drugs include faster availability for patient use and known safety concerns for the original indication. Disadvantages of new uses for old drugs may include lack of clinical evidence, unknown safety for the new clinical context, limited availability of information about new uses, and liability or legal concerns. Several methods of identifying potential new uses exist, including the observance of previously unknown desirable pharmacologic effects during clinical use, new knowledge of a mechanism of action leading to exploration of innovative therapeutic areas, or screening compound libraries for targeted clinical activity. Conclusions: There are many examples of recycling existing medications for new purposes. Pharmacy practitioners should be aware of this developing trend and know how to find information about utilizing old drugs in new ways.

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