The combination of epidural clonidine and S(+)-ketamine did not enhance analgesic efficacy beyond that for each individual drug in adult orthopedic surgery

The association of epidural clonidine or S(+)-ketamine did not result in a greater analgesic effect in the model of acute postoperative pain studied, although the interaction of epidural clonidine and S(+)-ketamine is not attributable to sharing of a common second messenger system.