Unintended effects of orphan product designation for rare neurological diseases.

Since the introduction of the Orphan Drug Act in 1983, designed to promote development of treatments for rare diseases, at least 378 orphan drugs have been approved. Incentives include financial support, tax credits, and perhaps most importantly, extended market exclusivity. These incentives have encouraged industry interest and accelerated research on rare diseases, allowing patients with orphan diseases access to treatments. However, extended market exclusivity has been associated with unacceptably high drug costs, both for newly developed drugs and for drugs that were previously widely available. We suggest that a paradoxical effect of orphan product exclusivity can be reduced patient access to existing drugs. In addition, the costs of each new drug are arguably unsustainable for patients and for the American health care system. Of all the specialties, neurology has the third highest number of orphan product designations, and neurological diseases account for at least one-fifth of rare diseases. Citing the use of tetrabenazine for chorea in Huntington disease, adrenocorticotropic hormone for infantile spasms, and enzyme replacement therapy with alglucosidase alpha for Pompe disease, we highlight these paradoxical effects.