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.

Size control of ropivacaine nano/micro-particles by soft-coating with peptide nanosheets for long-acting analgesia

“…In this study, the LA microparticle formulations were prepared by using SAP nanosheets to encapsulate RB particles in a soft-coating manner, which have shown two major advantages. On one hand, by forming a thin layer of peptide nanosheet coating around RB nano/micro-particles, this system achieved much higher capacity to encapsulate ropivacaine compared with previous strategies using traditional materials [40][41][42], which might greatly cut down the cost of fabrication. On the other hand, compared with our previously reported bottom-up strategies which were somehow complicated by relying on special interaction between LAs and the carrier materials, the current top-down strategy was much more straightforward and facile in obtaining particles with different size.…”

Controlled Release of Ropivacaine from Single-Armed (1-PCL) and Four-Armed PCL (4-PCL) Microspheres

“…Several studies on the microsphere-formulated ropivacaine have shown promise in the controlled release of drugs. Chitosan microspheres loaded with ropivacaine hydrochloride show linear release [14]. Ropivacaine hydrochloride carried by poly(lactic-coglycolic acid) (PLGA) has been found to prolong the release period during animal experiments [15].…”