In vivo assessment of percutaneous local anaesthetic preparations

Abstract

This study has demonstrated greater efficacy of a new percutaneous amethocaine preparation relative to Eutectic Mixture of Local Anaesthetics (EMLA). Initially, a double-blinded trial was undertaken on each preparation individually against placebo, as the recommended method of application was different for EMLA (2.5 g applied for 60 min under an occlusive dressing) and the amethocaine formulation (0.5 g applied for 30 min). Thereafter, the two preparations were compared directly, in a double-blinded study using a standardized application for both formulations. The results indicated that both preparations provided significant (chisquare; P < 0.001) percutaneous local anaesthesia when compared with placebo. The amethocaine preparation produced significant anaesthesia (chisquare, P < 0.001) after 30 min application. Furthermore, the amethocaine formulation demonstrated both increased rapidity of action and increased duration of effect, as determined by a two-tailed unpaired t test, in comparison with EMLA when application times of both 30 and 60 min were used for each preparation. The results of this study indicate that the amethocaine preparation provided more rapid and prolonged anaesthesia than EMLA. © 1989 British Journal of Anaesthesia.