Preparation of ropivacaine-loaded mesoporous bioactive glass microspheres and evaluation of their efficacy for sciatic nerve block

Local anesthetics are mainly used for regional anesthesia and analgesia. However, the duration of action is limited in clinical applications. In the present study, we developed a ropivacaine (RPC)-loaded mesoporous bioactive glass (MBG) microspheres for an extended analgesic duration. First, MBG microspheres were prepared using a template synthesis method. RPC was then loaded into the MBG microspheres through immersion, fol-lowed by centrifugation and drying. Finally, the RPC-loaded MBG microspheres were coated with a polylactic acid-b-polyethylene glycol (PLA-PEG) copolymer to obtain RPC-MBG composite microspheres (RPC micro-spheres). The particle size and zeta potential of the RPC microspheres were 192.3 +/- 9.6 nm and -35.6 +/- 3.5 mV, with entrapment efficiency (EE) of 88.2 +/- 3.2% and low cytotoxicity. In vitro, the release profile of RPC microspheres exhibited a biphasic pattern: an initial release burst within the first hour, followed by subsequent slower and sustained release. After performing a single-shot sciatic nerve block, a fast the an-esthetic effect and prolonged analgesic effect were achieved. Given the low cytotoxicity and sustained release, the RPC microspheres developed in this study could be used as a long-acting local anesthetic.