Due to their complexity the guidelines on ation are extremely complex. From a legal perspective, here’s a summary of FDA combined product guidelines.
Combination products are defined different ways throughout different countries. At present we are in the US is currently the only nation that has a legal definition of this term with other countries outlining the products they offer in their guidance documents. FDA regulations stipulate that combination products should be defined as combinations of drugs and devices. The law doesn’t define the definition of what a substance, device or a biological product is. It simply states that a mix product is one that combines two or more of the above items with different classifications.
The combination of more than one drug devices, or biological products cannot be considered as combination items. Although the FDA has guidelines regarding the combination of drugs, these do not qualify as product combinations since they’re not subject to the regulation of two centers.
Check out the FDA guidelines for more details about the combination of products, and how they should be regulated. There is a wealth of information on combination products on the official FDA site.