Repurposing Old Drugs For New Roles

Here is an interesting article about expanding the use of old, approved drugs for new purposes.  In theory, this is a good idea, since the safety profile of the drug and its various side effects would already be known, and sometimes “side effects” can mean the drug can be useful against other disorders than originally intended.  However, this requires additional testing to determine if the drug is actually effective in the new role for which it is being proposed. The problem is that when you consider expensive drugs still under patent, pharmaceutical companies have a patent incentive to do such testing, but not for low-cost generic drugs. The author proposes some ways around this: government funding, prize funds, leveraging existing data.  Given the cost of new drugs and the uncertainty of side effects, particularly long-term side effects, once they are in clinical use, repurposing old drugs has promise in being more safe and efficient.  From the article:

US Food and Drug Administration (FDA) approval of a new drug typically coincides with a period of patent protection, during which the manufacturer will often apply for additional indications to expand the market for the product. For example, the tyrosine kinase inhibitor imatinib (Gleevec; Novartis) was originally approved to treat Philadelphia chromosome–positive chronic myelogenous leukemia, but has since been approved for treatment of other cancers. Many noncancer drugs also follow this pattern, including botulinum toxin A (Botox; Allergan), which was originally approved for the treatment of strabismus and blepharospasm and subsequently approved for treatment of cervical dystonia, cosmetic uses, and chronic migraine.

This pattern of additional testing and approvals is common for more expensive on-patent drugs, but new indications are rarely sought for less-expensive generic drugs, for which it is more difficult to profit from the research. This creates a policy conundrum: follow-on innovation for low-cost generic products offers a rare opportunity to simultaneously improve health outcomes and likely reduce health care expenditures, but how could such research be encouraged?