Outlined by the FDA if it is difficult or unclear on determining the primary mode of action for the combination product, you can file a Request For Designation (RFD), which is outlined in 21 CFR Part 3, and the specific information to be included in the RFD is described in detail in 21 CFR 3.7. With this the FDA determines the combination product’s classification and lead agency assignment. However, the FDA’s designation response is binding and will dictate the regulatory path for the sponsor.

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