Combination products are assigned to Centers with primary jurisdiction for premarket reviews and regulation. The determination is based on “primary mode of action” of the combination product. Sponsors can determine their product’s PMOA, If the PMOA is unclear, a sponsor can petition the OCP to assign its product to a review center through a Request for Designation (RFD), also known as letter of request. In its RFD, a sponsor can suggest how a product should be categorized.After submitting a request for designation by the company the Office of Combinations Products will decide the most important aspect of the combination, either the drug or the device, through the Request for Designation (RFD) process. If it’s deemed the drug is the primary mode of action, it will be reviewed by CDER if its deemed the device is the primary mode of action, CDRH (Center for Devices and Radiological Health) will review it. So the regulatory requirements are not standardized for all combination products, but are specific based on whether it’s a drug/device, a biologic/device, or a drug/biologic.A single application can be submitted to lead center for market approval,however in some cases two applications are needed that allow the sponsor to claim some benefit that accrues only from approval under a particular type of application,