Implantable drug delivery systems

Implantable drug delivery systems provide extended release of a drug for the desired duration, usually over timespans of months and years. A broad range of materials are currently in use for the fabrication of implants, both nondegradable and biodegradable, the choice of which will depend on the drug being delivered, the type and length of drug release required, and whether or not the device can remain in place permanently. However, as all implants are exposed to tissues for prolonged periods, it is essential that each material is biocompatible to reduce undesirable cytotoxic effects. There are a wide variety of implantable devices in clinical use including subdermal implants, vaginal rings, intrauterine devices, ocular implants, and intracerebral implants. This chapter will discuss the use of both nondegradable and biodegradable materials for the manufacture of implantable drug delivery systems with an overview of how each type of material has been utilized in the production of experimental, patented, and/or marketed implantable drug delivery systems.