Complex of branched cyclodextrin and lidocaine prolonged the duration of peripheral nerve block

Although laboratories have tried to synthesize new local anesthetics, currently available local anesthetics rarely provide prolonged regional blockade. New models of sustained-release preparations of local anesthetics with liposomes and microspheres have been studied to prolong the duration of the effects of the local anesthetics. In the present study, we examined whether a complex of a branched cyclodextrin (CD), 6- O -α-D-maltosyl-β-cyclodextrin (G2-β-CD) and lidocaine could prolong local nerve block when compared with plain lidocaine. The sciatic nerve in male Sprague-Dawley rats was blocked with plain lidocaine ( n = 10), the complex of G2-β-CD + lidocaine ( n = 10), or plain G2-β-CD ( n = 4). Sensory block was assessed with a hotplate set at 56°C. The median duration of the block was longer in the complex group than in the plain lidocaine group (110 min; range, 70–150 min vs 55 min; range, 40–80 min; P < 0.05), thus demonstrating that the complex with CyD significantly prolonged the nerve block effect of lidocaine. In conclusion, the present study showed that this encapsulating technique with CyD is useful to expand local anesthetic effect in peripheral nerve blockade.