• J Sawyer, S Febbraro, S Masud, M A Ashburn, and J C Campbell.
• Prism Ideas Ltd, Regent House Princes Court, Beam Heath Way, Nantwich, Chesire CW5 7PQ, UK. james.sawyer@prismideas.com
• Br J Anaesth. 2009 Feb 1;102(2):210-5.

BackgroundWe compared the lidocaine/tetracaine patch [Synera (USA), Rapydan (Europe)], a novel heat-aided patch using a eutectic mixture of lidocaine 70 mg and tetracaine 70 mg, with a eutectic mixture of lidocaine 25 mg ml(-1) and prilocaine 25 mg ml(-1) (EMLA Cream). The agents were administered at different time periods for local topical anaesthesia before a vascular access procedure.MethodsIn this double-blind, paired study, 82 adult volunteers were randomized to receive the lidocaine/tetracaine patch on one anticubital surface and lidocaine/prilocaine cream on the other concurrently for 10, 20, 30, or 60 min before a vascular access procedure. Subjects rated pain intensity using a 100 mm visual analogue scale (VAS). Skin reactions and adverse events were also evaluated.ResultsMedian VAS scores were significantly lower for the lidocaine/tetracaine patch than for lidocaine/prilocaine cream in the 10 min (P=0.010), 20 min (P=0.042), and 30 min (P=0.001) application groups. The lidocaine/tetracaine patch was associated with significantly more erythema than lidocaine/prilocaine cream at 20, 30, and 60 min, whereas lidocaine/prilocaine cream produced more blanching than the lidocaine/tetracaine patch at 30 and 60 min. Two subjects reported nausea and faintness associated with the vascular access procedure; one was withdrawn from the study.ConclusionsThe lidocaine/tetracaine patch provided effective anaesthesia with an application time as short as 10 min and was better than lidocaine/prilocaine cream at all application times shorter than 60 min, demonstrating a substantial improvement in time to onset of anaesthesia. The lidocaine/tetracaine patch provided an important alternative to lidocaine/prilocaine cream for topical local anaesthesia.

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