ABSTRACT
Objective To investigate the efficacy ofpoly (lactic acid co castor oil) microspheres containing ropivacaine for sciatic nerve block of mice.Methods A total of 150 Kunming male mice were randomly assigned into 3 groups,namely placebo microspheres (lactic acid co castor oil) group (group A,n=50),ropivacaine injection group (group B,n=50) and ropivacaine microspheres group (group C,n=50).After sevoflurane anesthesia,the mouse was fixed on the operating table and the bilateral sciatic nerve was exposed.The corresponding preparations were implanted or injected near the sciatic nerve.Five mice were randomly selected from each group for the next experiments.Paw withdrawal thermal latency,the ability to splay and flex of the hind paw and plasma ropivacaine concentration were measured 10min,30min,1h,3h,5h,7h,10h,15h,30h and 48h after drug administration.Results The anesthetic effect of group C began to work at 3h.Compared with group B,the duration of sciatic nerve sensory block of group C was significantly longer and the effect of motor block was weaker.No anesthetic effect was observed in group A.The sensory and motor block of group B reached the peak at 1h,and the pharmacodynamics subsided at 7h.Compared with group B,the concentration of ropivacaine in group C increased slowly,and the peak value at 10h after administration was gradually decreased.Conclusions Ropivacaine loading poly (lactic acid co castor oil) microspheres can significantly extend the effect of ropivacaine on sciatic nerve sensory block.Compared with ropivacaine injection,motor block effect of ropivacaine loading poly (lactic acid co castor oil) microspheres is reduced and its plasma ropivacaine concentration fluctuation range is small.