Biodegradable Drug Delivery Implants

Abstract

Biodegradable drug delivery implants offer a compelling alternative to systemic pharmacotherapy in contexts where sustained local drug concentration is clinically superior -- oncology, orthopaedics, ophthalmology, and wound healing among them. The core appeal is straightforward: place the drug where it needs to act, release it at a controlled rate, and let the implant disappear without a retrieval procedure. What remains contested is which polymer matrix best serves which clinical context. This study introduces the Biodegradable Implant Performance Assessment Framework (BIPAF), evaluating five implant categories -- poly(lactic-co-glycolic acid) (PLGA) microsphere implants, polycaprolactone (PCL) matrix implants, chitosan-based hydrogel implants, poly(lactic acid) (PLA) film implants, and silk fibroin scaffold implants-- across four clinical deployment contexts using in vitro release data, in vivo biocompatibility assessments, and 24-month degradation studies from 386 implant specimens. Performance was scored using the Drug Delivery Effectiveness Score (DDES), a weighted composite of drug release kinetics (0.30), biocompatibility (0.20), mechanical integrity (0.20), degradation rate concordance (0.15), and manufacturing scalability (0.15). PLGA microspheres achieved the highest DDES (0.884), driven by superior drug release kinetics (0.920) and degradation rate concordance (0.900). PCL matrix implants ranked second (0.880) with the strongest mechanical integrity (0.920) -- critical for orthopaedic applications. Chitosan hydrogels posted the best biocompatibility (0.960) but lagged on mechanical integrity (0.780), limiting their utility to soft-tissue and ophthalmic applications. Context-specific deployment matching PLGA to oncology, PCL to orthopaedics, chitosan to ophthalmology, and silk fibroin to wound healing produced the highest aggregate therapeutic outcomes across all four contexts.