Repackaging FDA-approved drugs for degenerative diseases: promises and challenges.

Repurposing refers to the therapeutic use of a drug or drug candidate for a disease other than that for which it was originally intended. Repurposing is attractive as a drug development strategy since much is known about approved agents including their drug-likeness and pharmacokinetic features, dosing, safety, tolerability, formulation and manufacturing. Time savings are also robust accounting for several years of the drug development cycle. Tissue and cell-based assays, epidemiologic information and human studies identify approved drugs that might be repurposed from use in Alzheimer's disease and other neurodegenerative disorders. The total number of compounds available for repurposing that are brain-penetrant is relatively small. Intellectual property and patent protection issues for repurposed drugs are hurdles for this approach to drug development. Repurposing may contribute importantly to development of new therapies for neurodegenerative disorders.