Primary mode of action

The primary mode of action decides which FDA center leads a combination product: CDRH for a device action, CDER or CBER for a drug or biologic action. When it cannot be determined with reasonable certainty, FDA uses an assignment algorithm based on similar products and on safety and effectiveness questions.

Primary mode of action is the single mode of action of a combination product that provides the most important therapeutic action of the combination product. The most important therapeutic action is the mode of action expected to make the greatest contribution to the overall intended therapeutic effects of the combination product.

21 CFR, 3.2