Hydrogels have increasingly received considerable attention for local opioids delivery in order to sustained wound pain relief. However, burst release of drugs is a critical problem of hydrogels. To this aim, a local drug delivery system consisting of polycaprolactone (PCL) microspheres containing methadone hydrochloride/polyethylene glycol (PEG)-based hydrogels were developed to prolong drug release with potential utilization in pain treatment. Four different drug delivery systems, including methadone hydrochloride/PEG-(N 3 ) 4 -based hydrogel, methadone hydrochloride/PEG-(N 3 ) 2 -based hydrogel, methadone hydrochloride/PCL/PEG-(N 3 ) 4 , and methadone hydrochloride/PCL/PEG-(N 3 ) 2 composite hydrogels, were fabricated to investigate drug release profiles of these systems. The results showed that drug released can be controlled by both the double-barrier matrix (hydrogel/microsphere), and the crosslinking density of hydrogels. Therefore, methadone hydrochloride/PCL/PEG-(N 3 ) 2 composite hydrogel with high crosslinking density has great potential application in sustained release systems for wound pain relief.

Block copolymer micelles with a functional core have been synthesized and evaluated for their drug delivery capability. High drug loading was observed due to strong ionic interactions, while cytotoxicity of polymers was found to be low.

No abstract