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Comparative topical anaesthesia of EMLA and liposome-encapsulated tetracaine

Canadian Journal of Anaesthesia volume 44, pages 707–711 (1997)Cite this article

Abstract

Background

The eutectic mixture of local anaesthetics (EMLA) provides effective topical anaesthesia after a minimum of 60 to 90 mm application. Since liposome-encapsulated tetracaine (LET) can provide rapid dermal penetration, the goal of this study was to compare the local anaesthetic effects of EMLA and LET in human volunteers after 60 mm application.

Methods

After obtaining institutional approval and informed consent, healthy volunteers were recruited in a double blind, crossover, randomized trial. The study creams (0.5 ml EMLA and 0.5 ml LET 5%) were applied randomly to opposite arms for 60 min. The discomfort of iv cathetenzation was assessed using a visual analogue pain score (VAS). Cutaneous side effects of the creams were recorded.

Results

Sixty-one subjects were studied. Twenty-one were excluded because of technical difficulties. Forty subjects completed the study and were included in the data analysis. The mean (±SD) VAS was lower for LET than for EMLA (10.9 ± 9.0 mm vs 22.7 ± 17.1 mm, P < 0.001). Erythema secondary to vasodilatation occurred more frequent in the LET group than in the EMLA group (33 vs 3. P < 0.001). One subject with a history of atopy developed a rash at the LET application site.

Conclusion

Liposome-encapsulated tetracaine can provide a more effective topical anaesthesia than EMLA for intravenous catheterization after 60 min application. Clinical evaluations are necessary to determine the efficacy and safety of LET in providing topical anaesthesia for vanous invasive percutaneous procedures in other patient populations.

Résumé

Objectif

Le mélange eutectique d’anesthésique local (EMLA) appliqué pendant 60 à 90 minutes procure une anesthésie topique efficace. On sait que tétracaïne encapsulée dans les liposomes (LET) pénètre le derme rapidement. Cette étude a été entreprise pour comparer les effets anesthésiques locaux de l’EMLA et du LET chez des volontaires humains après 60 mm d’application.

Méthodes

Après obtention de l’approbation des instances appropriées et du consentement éclairé, des volontaires ont été recrutés dans une étude aléatoire croisée à double insu. Les crèmes (EMLA 0.5 ml et LET 5% 0,5 ml) ont été appliquées aléatoirement sur des bras opposés pendant 60 min. L’inconfort de la canulation veineuse a été évalué sur une échelle visuelle analogique (ÉVA). Les effets secondaires ont été notés.

Résultats

Soixante et un sujets ont participé à l’étude dont vingt et un ont été rejetés à cause de problèmes techniques. Quarante sujets ont complété l’étude et ont été conservés pour l’analyse des données. L’ÉVA moyenne (±ÉT) du LET était inférieure à celle de l’EMLA (10.9 ± 9.0 mm vs 22,7 ± 17.1. P < 0,001). L’érythème secondaire à la vasodilatation était plus fréquent dans le groupe LET que dans le groupe EMLA (33 vs 3, P < 0.001). Un des sujets considéré comine atopique a présenté de l’érythème au site d’application du LET.

Conclusion

La tétracaïne encapsulée dans les liposomes peut procurer une anesthésie topique plus efficace que l’EMLA pour la canulation veineuse après 60 min d’application. Des évaluations cliniques sont nécessaires pour déterminer l’efficacité et l’innocuité du LET pour l’anesthésie topique pendant des manipulations percutanées diverses chez d’autres groupes de patients.

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Affiliations

  1. Departments of Anaesthesia and Pharmacology, Dalhousie University, Halifax, Nova Scotia, Canada

    Orlando R. Hung, Laurel Comeau, Mark R. Riley, Stephen Tan, Sara Whynot & Michael Mezei

  2. College of Pharmacy, Dalhousie University, Halifax, Nova Scotia, Canada

    Michael Mezei

Authors
  1. Orlando R. Hung
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  2. Laurel Comeau
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  3. Mark R. Riley
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  4. Stephen Tan
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  5. Sara Whynot
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  6. Michael Mezei
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Corresponding author

Correspondence to Orlando R. Hung.

Additional information

Funding for This study was provided in part by Medical Research Council of Canada and Paincare Associates Canada Inc.

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Hung, O.R., Comeau, L., Riley, M.R. et al. Comparative topical anaesthesia of EMLA and liposome-encapsulated tetracaine. Can J Anaesth 44, 707–711 (1997). https://doi.org/10.1007/BF03013382

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Keywords

  • Tetracaine
  • Topical Anaesthesia
  • Prilocaine
  • Visual Analog Pain Scale
  • Amethocaine