Heated lidocaine/tetracaine patch (SyneraTM, RapydanTM) compared with lidocaine/prilocaine cream (EMLA®) for topical anaesthesia before vascular access
1 Prism Ideas Ltd, Regent House Princes Court, Beam Heath Way, Nantwich, Chesire CW5 7PQ, UK
2 Simbec Research Ltd, Merthyr Tydfil, UK
3 Shriners Hospital for Children, Salt Lake City, UT, USA
4 University of Utah, Salt Lake City, UT, USA
5 Penn Pain Medicine, University of Pennsylvania, Philadelphia, PA, USA
6 ZARS Pharma, Salt Lake City, UT, USA
7 Endo Pharmaceuticals, Inc., Chadds Ford, PA, USA
* Corresponding author. E-mail: james.sawyer{at}prismideas.com
Background: We compared the lidocaine/tetracaine patch [SyneraTM (USA), RapydanTM (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.
Methods: In 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.
Results: Median 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 Two subjects reported nausea and faintness associated with the vascular access procedure; one was withdrawn from the study.
Conclusions: The 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.
Keywords: anaesthetics local, lidocaine; anaesthetics local, prilocaine; anaesthetics local, tetracaine; pain; venepuncture
8 Present address: Parexel CPRU, London, UK
Declaration of interest. J.S. has received honoraria for work conducted on behalf of ZARS Pharma. S.M. owns shares of ZARS Pharma. M.A.A is a co-founder of ZARS Pharma, the sponsor of the clinical trial on which this paper is based. He also holds shares in ZARS Pharma and, during the conduct of the study, was an employee of ZARS. His role was to design the trial and act as a medical monitor. J.C.C. is an employee of Endo Pharmaceuticals.