Implantable drug delivery system: Frontiers of medicine-engineering interdisciplinary

Conventional drug delivery methods, such as oral administration and intravenous injection, are associated with several challenges including high systemic toxicity, difficulty in dosage control, and delayed therapeutic responses. These issues limit both the efficacy of treatments and patient compliance, thus becoming a bottleneck in the advancement of precision medicine. In recent years, implantable drug delivery systems (IDDS) have emerged as a promising frontier at the intersection of precision medicine and medical engineering. Through in vivo implantation coupled with signal response mechanisms, IDDS facilitates targeted drug delivery, dynamic regulation, and real-time responsiveness. These significantly enhance therapeutic efficacy while reducing toxicity levels, offering a new path to address the limitations inherent in traditional delivery methods. This article reviews the research progress of IDDS. The technical principles and module innovations are systematically elaborated based on three mechanisms: endogenous response, exogenous triggering, and closed-loop control. Furthermore, it explores the pivotal role that flexibilization and miniaturization of IDDS play in improving biocompatibility, tissue adhesion capabilities, and spatial adaptability. The article also summarizes application examples within typical disease models while analyzing core challenges related to clinical translation. Finally, it anticipates future development directions for integrating medical engineering into this evolving field.