The FDA’s Office of Combination Products would develop regulations and guidance for any combination products that are presented by a company. The Office of Combination Products would review and assign responsibility for combination products to one of the branches of the FDA, which are CDRH, CDER, and CBER. Its assignment to which branch of the FDA will come down to the primary mode of action (PMOA). Once assigned it will be subjected to its assigned branch’s classifications and regulations. So for your mentioned drug delivery system I would think its PMOA would be the drug component since that is what the most important aspect of it is so it would be assigned to CDER and for the implant treated with an antibiotic, I think the primary focus would be the implant characteristic so it would be assigned to CDRH.

Link:
https://www.fda.gov/CombinationProducts/RFDProcess/default.htm