Sustained-Release Hydromorphone Microparticles Produced by Supercritical Fluid Polymer Encapsulation.

Chronic cancer pain remains prevalent and severe for many patients, particularly in those with advanced disease. The effectiveness of analgesic/adjuvant drug treatments in routine practice has changed little in the last 30 years. To address these issues herein, we have developed sustained-release poly(lactic-co-glycolic acid) microparticles of hydromorphone for intrathecal injection aimed at producing prolonged periods of satisfactory analgesia in patients, as a novel strategy for alleviation of intractable cancer-related pain. These hydromorphone-loaded microparticles were produced successfully using organic solvent-free supercritical fluid polymer encapsulation. Drug loading at 9.2% and encapsulation efficacy at 92% were achieved for particles in the desired size range (20-45 μm) with sustained release over a 5-week period in vitro.