Over the past 20 years, there has been a significant increase in the use of implantable drug delivery devices, and silicone elastomers have played a crucial role in enabling this growth. This eBook is designed to explore the role of silicone as an excipient in implantable drug delivery devices. We will examine critical considerations when using APIs in conjunction with silicones and explore how silicones can be tailored to address the various challenges posed by different APIs and device designs.