The influence of midazolam on the plasma concentrations of bupivacaine and lidocaine after caudal injection of a mixture of the local anesthetics in children.

Twenty children undergoing surgery received a caudal block using 1 ml per kg of a mixture of 50% lidocaine (1%) and 50% bupivacaine (0.25%). They were randomly allocated to two groups, one of which received midazolam 0.4 mg/kg rectally as premedication. Midazolam administration resulted in a significantly lower AUC value for lidocaine but did not influence the plasma concentrations of bupivacaine.