Chronobiology international
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Because a eutectic mixture of lidocaine and procaine (EMLA cream) is used to treat pain in children who are undergoing venipuncture for screening clinical presurgery laboratory tests, this study was designed to investigate the influence of the time of application of EMLA cream on lidocaine transcutaneous absorption in children. The same phenomenon was also studied in rats. Local application of EMLA (right and left cubital fossae) was performed 1 hour before venipuncture in two groups of children (0.5 g/kg body weight at two sites), at 08:15 or 16.15 h; blood samples were performed 1 h later. ⋯ Plasma lidocaine levels were assayed according to an immunoenzymatic method (Abbott). Our data indicate that the lidocaine plasma levels were significantly different: higher in the evening for the children or in the morning for the rats. The plasma level of the local anesthetics (LA) represents an elimination route and thus may be inversely correlated to the skin amount of the LA.