Eutectic mixture of lidocaine and

Similar to Voltaren" Emulgel, oily droplets of an eutectic mixture of lidocaine and prilocaine are dispersed in a hydrogel to provide local anesthesia to the skin for injections and siugical treatment (Emla cream). A further possibility is the dermal administration of a liposome dispersion as a spray (Heparin PUR ratiopharm Spriih-gel "). After administration, water and isopropylic alcohol evaporate partially resulting in an increase of concentration and in a transition from the initial liposome dispersion into a lamellar liquid crystal [32]. The therapeutic effect appears to be influenced favorably by the presence of lecithins rather than by the degree of liposome dispersion. 

EMLA cream (lidocaine (lignocaine) 2.5% and prilocaine 2.5%) is an emulsion in which the oil phase is a eutectic mixture of lidocaine and prilocaine in a ratio of 1 1 by weight. It is available in 5 g and 30 g tubes. It is also available as an anaesthetic disc. This consists of a single-dose unit of EMLA contained within an occlusive dressing. The disc contains 1 g EMLA emulsion, the active contact surface being approximately 10 cm2. The surface area of the entire anaesthetic disc is approximately 40 cm2. EMLA (1 g) contains lidocaine 25 mg, prilocaine 25 mg with thickening agents, water, NaHCOB, etc., at a pH of about 9. 

Uhari M. Eutectic mixture of lidocaine and prilocaine for alleviahng vaccination pain in infants. Pediatrics 1993 92 719-721. 

Nyqvist-Mayer, A. A., Brodin, A. F. and Frank, S. G., Drug release studies on an oil-water emulsion based on a eutectic mixture of lidocaine and prilocaine as the dispensed phase, J. Pharm. Sci, 75, 365-373 (1986). 

Shukla, A., Krause, A., and NeuberL R.H.H. 2003 Microemulsions as colloidal vehicle systems for dermal drug delivery. Part IV Investigation of microemulsion systems based on a eutectic mixture of lidocaine and prilocaine as the colloidal phase by dynamic light scattering. J. Pharm. Pharmacol. 55 741-748. 

The introduction of a eutectic mixture of lidocaine (2.5%) and prilocaine (2.5%) (EMLa) bridges the gap between topical and infiltration anesthesia. The efficacy of this combination lies in the fact that the mixture of prilocaine and lidocaine has a melting point less than that of either compound alone, existing at room temperature as an oil that can penetrate intact skin. EMLA cream produces anesthesia to a maximum depth of 5 mm and is applied as a cream on intact skin under an occlusive dressing, for procedures involving skin and superficial subcutaneous structures (e.g., venipuncture and skin graft harvesting). EMLA must not be used on mucous membranes or abraded skin, as rapid absorption across these surfaces may result in systemic toxicity. 

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. 

EMLA cream (lidocaine 2.5% and prilocaine 2.5%) consists of a eutectic mixture of focal anesthetics. It is used to provide topical anesthetic to intact skin. Other topical preparations are effective only on mucosal surfaces. EMLA has been shown to reduce pain on venipuncture and provide substantial anesthesia for skin graft donor sites. No significant local or systemic toxicity has been demonstrated. 

Clinical use Topical anesthesia is easily achieved using an eutectic mixture of the LAs prilocaine and lidocaine (EMLA, see Lidocaine). 

Juhlin L, Hagglund G, Evers H. Absorption of lidocaine and prilocaine after application of a eutectic mixture of local anesthetic (EMLA) on normal and diseased skin. Acta Derm Venerol (Stock) 1989 69 18-22. 

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. 

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. 

Generic Names topical lidocaine/prilocaine, topical lidocaine/tetracaine, tetracaine gel, 4% liposomal lidocaine, 1,1,1,3,3-pentafluoropro-pane and 1,1,1,2-tetrafluoroethane Trade/Proprietary Names EMLA (Eutectic Mixture of Local Anesthetics), Synera", Ametop Gel , LMX-4 , PainEase (vapocoolant spray)... 

Since absorption of local anesthetics through the skin is enhanced by heat, a topical patch with an intrinsic heating system was developed [4], This incorporates a controlled heat-assisted delivery system that is physically separated from a eutectic mixture of 70 mg of lidocaine and 70 mg of tetracaine. The surface area of the entire Synera patch is approximately 50 cm, 10 cm of which is active. 

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%). 

Local anesthetics or sedation are not required for the CROSS. Generally, patients feel bearable prickling and burning sensation during the procedure. If needed, a topical anesthetic cream, such as EMLA cream (eutectic mixture of 2.5% lidocaine-HCl and 2.5% prilocaine ... 

With the development of DESs, they have been applied on some polymerization reactions that are carried out at relatively high temperatures. In these synthetic processes, the eutectic mixtures can act as true solvent-template reactant systems, and thus the DES is at the same time the precursor, the template, and the reactant medium for the fabrication of the desired polymeric material with a defined morphology or chemical composition. Monte and co-workers have reported i) the frontal polymerizations carried out in the eutectic mixtures ChCl/Acrylic acid and ChCl/Mac, " ii) the synthesis of poly(octane-diol-co-citrate) elastomers using eutectic mixtures of 1,8-octanediol and lidocaine at temperatures below 100 C (see Figure 20.3.4), " and iii) the synthesis of poly(acrylic acid)-carbon nanotube composites in the eutectic mixture ChCl/Aciylic acid. " ... 

Mixing lidocaine base and prilocaine base in equal parts, at room temperature, gives a eutectic mixture. This mixture is emulsified in a base that consists mainly of water and polyoxyethylene castor oil, and the anesthetics are added to the oily phase. Phenol has an excellent oil/water partition coelEcient. The oils lower the toxicity of phenol, but also slow down its rate of penetration as well as absorption of the local anesthetics. There is a competition between the phenol solution and the EMLA, which changes the activity and penetration of the combined molecules. 

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]. 

Lidocaine [2-(diethylamino)-N-(2, 6-dimethylphenyl) acetamide monohydrochloride] is the most commonly used amino amide-type local anesthetic. Lidocaine is very lipid soluble and, thus, has a more rapid onset and a longer duration of action than most amino ester-type local anesthetics, such as procaine and tetracaine. It can be administered parenterally (with or without epinephrine) or topically either by itself or in combination with prilocaine or etidocaine as a eutectic mixture that is very popular with pediatric patients. The use of lidocaine-epinephrine mixtures should be avoided, however, in areas with limited vascular supply to prevent tissue necrosis. Lidocaine also frequently is used as a class IB antiarrhythmic agent for the treatment of ventricular arrhythmias, both because it binds and inhibits sodium channels in the cardiac muscle and because of its longer duration of action than amino ester-type local anesthetics. 

Subsequent studies have supported the above results. For instance, ibuprofen terpene eutectic systems vs. a saturated aqueous solution of ibuprofen applied to untreated and to terpene pretreated skin were reported to cause a significant flux enhancement [59]. A system composed of ibuprofen thymol 40 60 (% w/w) produced a flux 5.9 and 12.7 times higher than the flux values from a saturated aqueous solution with thymol pretreated skin and from a saturated aqueous solution across nonpretreated skin, respectively. Analogous data were achieved in permeation experiments through snake skin with lidocaine menthol eutectic mixtures [60]. 

Lidocaine is added by dehquescing lidocaine crystals and levomenthol together. The eutectic mixture is than emulsified in an aqueous gel. The biopharmaceutic advantage of this principle is that a molecular dispersion of the lipophilic lidocaine base in a hydrophihc preparation is formulated. 

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