Polymeric implantable drug delivery systems have remarkable potential for systemic delivery of various therapeutic agents. Generally, drug-loaded implants do not require a vehicle for delivery and can be used to attain prolonged delivery into the systemic circulation of active pharmaceutical ingredients (APIs) with enhanced drug bioavailability. Furthermore, implants can provide drug release ranging from months to years, which improves patient compliance, especially for poorly bioavailable and rapidly metabolized compounds. Continuous manufacturing technology (e.g., hot-melt extrusion, or HME) has been successfully employed to prepare drug-loaded single-unit polymeric implants. Employing heat and mechanical shear, such systems retain the stability of thermolabile therapeutics (e.g., proteins) in implants. HME has emerged as important because of its varied applications that combine economic viability with solvent-free and easy scale-up processing. Moreover, it has been recognized from a quality-by-design (QbD) viewpoint by the FDA.