title: Preparation of novel biodegradable ropivacaine microspheres and evaluation of their efficacy in sciatic nerve block in mice.
abstract: In this study, ropivacaine chitosan-loaded microspheres for subcutaneous administration were developed. The systems were characterized in terms of surface morphology, particle size, encapsulation efficiency, and in vitro release behavior. Results showed that the microspheres had drug loading rate of 7.3% and encapsulation efficiency of 91.2%, and their average diameter was 2.62±0.76 µm. The morphology study revealed that the microspheres are uniform monodispersed spheres and did not form aggregates in aqueous solution. It was clearly observed that the release profile of ropivacaine microspheres exhibited a biphasic pattern: the initial burst release within the first 2 hours and a following slower and sustained release over a long time. In vivo, a greater area under the plasma concentration-time curve from 0 to t (AUC0- t ) was obtained from the microspheres (4.27-fold), than from the injection group, which indicated that there was a significantly improved systemic exposure to ropivacaine. Pharmacodynamics result showed that preparing ropivacaine as microsphere preparation could not only extend the drug effect time but also decrease the administration dosage.
authors.affiliation: Department of Anesthesiology, Putuo Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, People's Republic of China.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Ni
authors.affiliation: Department of Anesthesiology, Putuo Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, People's Republic of China.
authors.forename: Wurong
authors.initials: W
authors.lastname: Chen
authors.affiliation: Department of Anesthesiology, Putuo Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, People's Republic of China.
authors.forename: Lei
authors.initials: L
authors.lastname: Tong
authors.affiliation: Department of Anesthesiology, Putuo Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, People's Republic of China.
authors.forename: Jue
authors.initials: J
authors.lastname: Cao
authors.affiliation: Department of Anesthesiology, Putuo Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, People's Republic of China.
authors.forename: Chao
authors.initials: C
authors.lastname: Ji
mesh_terms: D000577:Amides / Q000008:administration & dosage* / Q000737:chemistry / Q000494:pharmacology*; D000818:Animals; D007279:Injections, Subcutaneous; D051379:Mice; D008815:Mice, Inbred Strains; D008863:Microspheres; D009407:Nerve Block / Q000379:methods*; D010316:Particle Size; D051381:Rats; D017207:Rats, Sprague-Dawley; D000077212:Ropivacaine; D012584:Sciatic Nerve / Q000187:drug effects*; D013499:Surface Properties
chemical_list: D000577:Amides; D000077212:Ropivacaine
keywords: chitosan; in vitro release; microspheres; pharmacodynamics; ropivacaine