Even though such products are controversial, with critics asserting that they only offer minimal clinical advantages besides convenience, the potential benefit for the patient is a financial one. Essentially, patients would make just one insurance co-payment when one drug replaces two.

FDA's New Focus In the past, FDA asked manufacturers to identify for themselves a product's primary mode of action and recommend the center to lead the review. Under a new proposal published in May, the primary mode of action would be defined as "the single mode of action (drug, device, or biological product) of a combination product that provides the most important therapeutic action." The agency notes, "This would be the mode of action that is expected to make the greatest contribution to the overall therapeutic effects." In situations when the most important therapeutic action cannot be easily determined, FDA would assign the product to a center evaluating a similar product. But many of the issues relating to combination product regulation would remain. For example, there is no consistent precedent at FDA for directing the product to the appropriate jurisdiction (device vs. drug).

In addition to the drug-drug combinations, other products that are receiving considerable attention include drug-eluting stents and orthopedic implants with genetically engineered human protein and antibiotic bone cement. FDA notes that these combination products represent a nascent category employing cutting-edge technologies "that hold great promise for advancing patient care." None of these mixed combinations fits precisely into any of FDA's traditional categories for regulatory review: drugs, devices, or biological products.