The effect of low-dose naloxone on the anticonvulsant action of ketamine on local anaesthetics-induced convulsion

Objective To observe the anticonvulsant action of ketamine (KT) on convulsion induced by ropivacaine (R),bupivacaine (B) and lidocaine (L) as well as the effects of combined administration of low-dose naloxone (NL) and KT on the convulsion induced by R,B and L. Methods A low dose of NL (10 ng/kg) was administered intraperitoneally (ip),followed by administration of KT (10 mg/kg) at an interval of 5 min,and induction doses of R,B and L (89.5 mg/kg,100 mg/kg and 60 mg/kg) ip. The duration,times and rate of convulsion were noted,and the ED50 values of R,B and L were determined 5 min after KT (20 mg/kg) ip injection in mice by sequential method. Results The ED50 values of R,B and L were elevated by KT (20 mg/kg) (P0.05,P0.01). The administration of low-dose NL combined with KT could shorten the L-induced convulsion duration and reduce the convulsion times (P0.05,P0.01),while low-dose NL had no significant effect on the anticonvulsive action of KT on the duration,times and rate of convulsion induced by R and B (P0.05). Conclusion Ketamine can intensify the convulsive effect induced by ropivacaine,bupivacaine and lidocaine,while low doses of naloxone can strengthen the anticonvulsant action of ketamine on lidocaine-induced convulsion.