Once the Food and Drug Administration (FDA) approves a new prescription drug for one medical indication, physicians are free to prescribe it for virtually any condition. While there are downsides of prescribing drugs “off-label,” it allows patients and payors to benefit as physicians test drugs under real-world conditions and identify new applications.

Because formal clinical trials and the FDA review process can take years, valuable new uses of a drug may be validated by studies in peer-reviewed medical journals years before the new indication becomes officially approved. And because of research and regulatory costs, drug makers cannot justify pursuing FDA approval for new indications, even when a new indication is highly cost-effective for purchasers, plans, and patients. Indeed, some diagnoses have no “on-label” drugs and are treated entirely on an off-label basis.

With the new Medicare drug benefit (Medicare Part D), the federal government will become the world’s largest buyer of prescription drugs. In Part D, a prescription drug is coverable by a Medicare drug plan (PDP or MA-PD) only if it is prescribed for a medically accepted indication as defined under federal Medicaid law. This includes uses that are approved by the FDA or supported by a citation in one of four drug compendia:

· American Medical Association Drug Evaluations

· American Hospital Formulary Service Drug Information

· DRUGDEX Information System

· United States Pharmacopeia Drug Information

Because of this restriction in the Medicare Modernization Act, indications that are supported in peer-reviewed medical literature but not yet approved by the FDA or accepted in one of the compendia are not “medically accepted” by Medicare. In such cases, the Medicare drug plans may not pay for the drug.

While this helps Medicare drug plans manage their financial exposure and allows them to crack down on inappropriate drug therapy, it also means that it’ll be harder for physicians to identify valuable new uses of medications. As we loose this critically important path to expanding our evidence base, patients and the economy will suffer.

This is yet another reason why we need a comprehensive approach to post-market surveillance and assessment of prescription drugs, continuous improvement of the evidence base of what works, and more effective ways to bring that evidence to day-to-day clinical practice.