Objective:To evaluate the efficacy of liposomal bupivacaine (LB) for sciatic nerve block in mice.Methods:Twenty-four healthy adult male C57BL/6 mice, aged 6-8 weeks, weighing 25-30 g, were divided into 4 groups ( n=6 each) using a random number table method: 1.33% LB 80 μl group (group A), 1.33% LB 40 μl group (group B), 0.66% LB 80 μl group (group C), and 0.66% LB 40 μl group (group D). The sciatic nerve block was performed using the corresponding concentration of LB or the equal volume of LB in each group. The mechanical paw withdrawal threshold (MWT) was measured using Von Frey filaments immediately after sciatic nerve block, at 5 min of block, and every 1 h until MWT recovered to the baseline level. The sciatic nerve block time-MWT curve was plotted to calculate the area under the curve (AUC). Results:The time-MWT curves exhibited similar bimodal characteristics in each group. From the time point immediately after the blockade to the first MWT peak after the blockade, there were no statistically significant differences in the AUC among the four groups ( P>0.05). From the first MWT peak to the first trough, the AUC was significantly greater in A group than in B, C and D groups and in B and C groups than in D group ( P<0.05). From the first trough to the second MWT peak, there was no significant difference in the AUC between A group and D group ( P>0.05), and the AUC was significantly greater in B and C groups than in A and D groups ( P<0.05). From the second MWT peak to the baseline level, the AUC was significantly greater in A group than in B, C and D groups ( P<0.05), and there was no significant difference in the AUC among B, C and D groups ( P>0.05). In the total duration of the sciatic nerve block, the AUC was significantly greater in A group than in B, C and D groups and in B and C groups than in D group ( P<0.05).There was no significant difference in the AUC between B group and C group ( P>0.05). Conclusions:LB exhibits characteristic bimodal changes when used for sciatic nerve block; higher concentrations and volume of LB result in stronger and longer-lasting block effects in mice.

Objective:To evaluate the efficacy of liposomal bupivacaine (LB) for sciatic nerve block in mice.Methods:Twenty-four healthy adult male C57BL/6 mice, aged 6-8 weeks, weighing 25-30 g, were divided into 4 groups ( n=6 each) using a random number table method: 1.33% LB 80 μl group (group A), 1.33% LB 40 μl group (group B), 0.66% LB 80 μl group (group C), and 0.66% LB 40 μl group (group D). The sciatic nerve block was performed using the corresponding concentration of LB or the equal volume of LB in each group. The mechanical paw withdrawal threshold (MWT) was measured using Von Frey filaments immediately after sciatic nerve block, at 5 min of block, and every 1 h until MWT recovered to the baseline level. The sciatic nerve block time-MWT curve was plotted to calculate the area under the curve (AUC). Results:The time-MWT curves exhibited similar bimodal characteristics in each group. From the time point immediately after the blockade to the first MWT peak after the blockade, there were no statistically significant differences in the AUC among the four groups ( P>0.05). From the first MWT peak to the first trough, the AUC was significantly greater in A group than in B, C and D groups and in B and C groups than in D group ( P<0.05). From the first trough to the second MWT peak, there was no significant difference in the AUC between A group and D group ( P>0.05), and the AUC was significantly greater in B and C groups than in A and D groups ( P<0.05). From the second MWT peak to the baseline level, the AUC was significantly greater in A group than in B, C and D groups ( P<0.05), and there was no significant difference in the AUC among B, C and D groups ( P>0.05). In the total duration of the sciatic nerve block, the AUC was significantly greater in A group than in B, C and D groups and in B and C groups than in D group ( P<0.05).There was no significant difference in the AUC between B group and C group ( P>0.05). Conclusions:LB exhibits characteristic bimodal changes when used for sciatic nerve block; higher concentrations and volume of LB result in stronger and longer-lasting block effects in mice.