Eutectic mixture of local anaesthetics

III.b.8.1. Skin. Surface anaesthesia of the skin can be produced with help of a cream containing a eutectic mixture of local anaesthetics (EMLA), which is a water/oil emulsion of equal parts of prilocaine and lidocaine with particularly good penetration capacity. EMLA is applied under occlusion, around 40-60 minutes before the planned intervention. This is an effective way of producing anaesthesia before needle punctures and minor, painful, procedures. The method is excellent, particularly in paediatrics, to reduce fear and pain. 

Altai N, Brasseur L, Chauvin M, Bouhassira D. Effects of single and repeated applications of a eutectic mixture of local anaesthetics (EMLA) cream on spontaneous and evoked pain in post-herpetic neuralgia. Pain 1999 81(l-2) 203-9. 

EMLA (eutectic mixture of local anaesthetics a combination of two local anaesthetics, lidocaine and prilocaine in a cream) is capable of producing skin thickness analgesia from topical administration. The cream is applied for a period of 1-2 hours under an occlusive dressing. EMLA is indicated prior to venepuncture (particularly in children) and whenever pre-injection analgesia of the skin is required. 

Topical anaesthesia prior to venepuncture may be necessary. This technique with EMLA (eutectic mixture of local anaesthetics) cream may be used by radiographers under patient group directions. See Chapter 12. 

Parenteral administration can be associated with pain at the injection site. The so-called injection fear may be diminished by applying topically anaesthetics prior to injection. Eutectic mixtures of local anaesthetics (e.g. lidocaine/ prilocaine cream or a tetracaine gel) have proven to be effective and well-tolerated in the relief of pain associated with intramuscular injections, venepuncture or intravenous injection in adults and children. 

The authors conclude that the immature skin layer in extremely low-birth-weight infants in conjxmction with the lipophilicity of tetracaine are the most likely culprits for the bradyarrhythmia described above and surest to consider alternative substances such as Eutectic Mixture of Local Anaesthetics (EMLA) cream (lidocaine 25% and prilocaine 2.5%). 

Lidocaine is a local anaesthetic which is available as a free base and hydrochloride salt. Lidocaine base is known to form eutectic mixture with prilocaine base and this eutectic mixture forms a dispersed phase of EMLA emulsion cream. Shukla et al. reported that with the help of microemulsification, the drug loading can be increased from 5% (present in EMLA cream) to 20% which may result in quick action by virtue of higher concentration gradient across the skin [49]. 

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