As you have mentioned already, combination products are combined drugs, devices, and/or biological products with one another, and are a growing and important category of therapeutic and diagnostic products. Similar to medical devices classification, combination products are also classified into 9 different types. Regarding the review, combination products are assigned to an FDA center which will have primary jurisdiction for its premarket review and post-market regulation. This is based on a determination of the primary mode of action in short (PMOA) of the combination product that provides the most important therapeutic action of the combination product.