Compacted solid implant formulations for long-term buprenorphine delivery

Opioid use disorder (OUD) remains a major public health challenge in the United States, and medication-assisted treatment with buprenorphine, a μ-opioid receptor partial agonist, is a cornerstone of effective management. Currently marketed long-acting buprenorphine products provide drug release for 1 week or 1 month. Here, we describe the development of new biodegradable PLGA rod formulations capable of sustaining buprenorphine release for ≥3 months. Poly(lactide-co-glycolide) (PLGA) and buprenorphine free base were thermally compacted into solid rods using a plastometer at 165-180 °C under a compression load of 4-16 kg. A primary objective of this formulation strategy was to minimize the initial burst release characteristic of conventional PLGA systems by reducing interconnected pore formation through compaction. The resulting implants contain 70% w/w buprenorphine and are straightforward to manufacture. In vivo pharmacokinetic evaluations in both rat and dog models demonstrated sustained plasma buprenorphine concentrations for more than 3 months. These long-acting implants may provide extended therapeutic coverage compared with existing products, potentially improving patient adherence and clinical outcomes in OUD treatment.