Endo Pharmaceuticals Inc has releasedSynera (lidocaine 70 mg and tetracaine 70mg), a topical anesthetic patch approvedfor use in patients aged 3 years and older(safety of Synera has been demonstratedin patients as young as 4 months old).Synera will be available in institutionalsettings to prevent pain from superficialvenous access and superficial dermatologicprocedures, such as excision, electrodessication,and shave biopsy.1
Although Synera is appropriate for usein both adult and pediatric populations,Endo Pharmaceuticals is especially awareof its need in hospitalized children.Patients less than 15 years old spendapproximately 11.5 million days in thehospital. Endo Pharmaceuticals promotesSynera to prevent pain, thus increasingpatient comfort and quality of care.1
Mechanism of Action
Synera consists of an oil emulsion oflidocaine and tetracaine as a eutectic mixture.The active ingredients cause localanesthesia by blockade of the sodium ionchannels that are required for neuronalimpulses and conduction.2
In addition to its active ingredients,Synera exhibits a warming component toaugment the local anesthetic effect byenhancing its delivery. The heat generationand skin warming allow for the desirableeffect of vasodilation. Upon removalfrom its packaging and exposure to oxygen,the patch begins to heat. Maximumskin temperature will not exceed 40º C.2
Several randomized, double-blind,placebo-controlled studies evaluatedthe efficacy of Synera in both childrenand adults. The first series of studiescompared Synera with placebo prior tosuperficial venous access. The patch wasapplied 20 minutes prior to the needlestick. Results were measured with a 100-mm visual analog scale (VAS) and determinedthat there was less pain withSynera than with placebo.2
Additional clinical studies assessed theefficacy of Synera for superficial dermatologicprocedures in adult and pediatricpopulations. In double-blind, randomizedstudies, Synera was applied 30 minutesbefore the procedure in both pediatricand adult patients. Synera was foundmore effective than placebo as assessedby VAS scores.2
The significance of Synera's heatingcomponent was evaluated in one double-blind, randomized trial. Prior tovenipuncture, 250 adult patients receivedeither Synera alone or Synerawith heat. The group with the heatingcomponent reported less pain than thegroup without.2
For anesthesia prior to venipuncture orintravenous cannulation, Synera shouldbe applied to the affected area 20 to 30minutes prior to the needle stick. Forsuperficial dermatologic procedures,Synera should be applied 30 minutesbefore the procedure.2
The patch must be applied immediatelyafter opening the package and shouldalways be applied to intact skin. The patchshould be removed if a burning or irritatedsensation occurs.2 In clinical trials, themost common side effects were erythema,blanching, and edema, and these sideeffects resolved after treatment.1
The use of Synera is contraindicated inpatients with a history of sensitivity tolidocaine, tetracaine, para-aminobenzoicacid, or any of the patch's other components.The Synera patch must be removedprior to magnetic resonance imaging.2
Multiple or sequential Synera patchesshould not be used, nor should the patchbe applied for longer than recommended.Even after use, a Synera patch will containat least 90% of its initial quantity of drug.To avoid accidental overdose, its properdisposal is imperative—the sticky sidesmust be folded together, and then thepatch must be disposed of in a containerout of reach of children and pets.2
Synera should be used cautiously inpatients with a history of increased sensitivityto any of its components. Patientswith severe hepatic disease or pseudocholinesterasedeficiency may not be ableto adequately metabolize the lidocaineand tetracaine, and therefore may be atincreased risk for toxic levels. Synerashould not be used on mucous membranes.Avoid contact with the eyes; goodhand washing should be practiced afterhandling the patch to avoid accidentalcontamination of the eyes. Synera is classifiedas in Pregnancy Category B.2
Dr. Holmberg is a pharmacist withPhoenix Children's Hospital, Phoenix,Ariz.
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