Originally Published MDDI October 2005
By Erik Swain
FDA's Office of Combination Products finalized a rule in August defining how to establish a product's primary mode of action, which determines which center leads its review.
Industry reacted mostly favorably to the definitions in the proposed rule, so the final rule has few changes. Most significant is an increased emphasis on a product's intended use. Parts of the proposed rule derived from issues raised at two public meetings in 2002.
The rule defines mode of action as “the means by which a product achieves its intended therapeutic effect or action.” Many combination products have more than one mode of action. For a product to be considered to have a device mode of action, it must meet three requirements. First, it must meet the definition of a medical device contained in the Food, Drug, and Cosmetic Act. In addition, it must not have biological composition, and it must not achieve its intended purposes though chemical action or metabolization.
The rule defines primary mode of action as “the single mode of action of a combination product that provides the most important therapeutic action of the combination product.” It defines most important therapeutic action as “the mode of action that is expected to make the greatest contribution to the overall intended therapeutic effects of the combination product.”
The office will use a two-part procedure for devices that have two completely different modes of action that are not subordinate to each other. Under the first part, the assignment will go to the center that regulates products with the most similar safety and effectiveness issues. If none exist, the second part of the procedure is used. That assigns the product to the center with the most expertise to handle the safety and effectiveness questions the product is likely to present.
One comment expressed concern that the term therapeutic action would bias the office toward drugs and biologics, which use that term frequently, at the expense of devices. FDA assured industry that would not be the case.
Another asked how FDA would determine the most significant safety and effectiveness issues raised by a product. The agency says it will consider a number of questions, including intended use, overall therapeutic effect, potential for clinically significant failure modes, presence of novel or complex designs, and risks posed by the various components. FDA does not plan to issue a guidance document on this topic, but it will consider doing so if it determines more clarity is needed.
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