Create a limit stage, and set the selection criteria to pass only medical grade materials. The properties to include as the selection criteria will depend on which data table you are using in the project.
In MaterialUniverse, there are a number of medical properties listed under Healthcare and food.
In Prospector Plastics, under Key Features, Uses & Ratings, select Medical Devices from the Uses list, and USP from the Agency Ratings list.
In CAMPUS and M-Base Plastics, under Characteristics, select Medical from the Applications list, and US Pharmacopeia Class VI from the Ecological evaluation list.