Analgesic and anti-inflammatory effects of lignocaine-prilocaine (EMLA) cream in human burn injury

Pain relief may be improved by reducing sensitization of nociceptive pathways caused by tissue injury. Such a reduction depends mainly on inhibition of local inflammatory changes and the relation between duration of nociceptive block and nociceptive input. In this study we examined if prolonged topical treatment with local anaesthetics could reduce late hyperalgesia and local inflammation after burn injury in healthy volunteers. The effects of EMLA treatment for 8 h after burn on hyperalgesia, inflammation and wound healing were compared with the contralateral placebo-treated leg for 48 h after bilateral burn injuries (15 x 25 mm, 49 degrees C for 5 min) in a double-blind, randomized study in 12 healthy volunteers. Wound healing was studied 1 and 2 weeks after injury. Neither mechanical nor thermal primary hyperalgesia were affected significantly by prolonged EMLA treatment. Secondary hyperalgesia and skin erythema were also not changed. Seven of 12 placebo-treated legs developed blisters, in contrast with four of 12 EMLA-treated legs. Wound healing showed no apparent differences. Our data suggest that prolonged, topical treatment with local anaesthetics did not reduce local inflammation and late hyperalgesia.