Emla

Dermatology , Drugs / November 11, 2016

Class: Topical Preparations
Dosage Form: Cream
Description: Local anesthetic
Stock: Available
Manufacturer: AstraZeneca

Composition:

1 g cream contains:
Active Ingredients:
Lidocaine…………25 mg
Prilocaine…………25 mg
Excipients:
Carbomer, polyoxyethylene hydrated castor oil. Sodium hydroxide to pH 8.7-9.7.

Properties:

Pharmacodynamics
Emla cream contains lidocaine and prilocaine, which are local anesthetics of the amide type. On penetration into the epidermis and dermis, these substances produce dermal anaesthesia. The degree of anesthesia depends on application time and dose.
Intact Skin
With an application time of 1-2 hours, the effect lasts for approximately two hours after the occlusive dressing has been removed.
In clinical studies of Emla on intact skin, no differences in safety or efficacy (including anesthetic onset time) were observed between geriatric patients (aged 65-96 years) and younger patients.
The superficial vascular bed is affected by Emla, and this can cause transient paleness or redness. These reactions appear to occur more raidly in atopic dermatitis, after only 30-60 minutes, indicating more rapid absorption through the skin (see also Warnings).
A study in healthy volunteers with intact skin shows that in 90% the anaesthesia is sufficient for use of biopsy punch (4 mm in diameter) to an insertion depth of 2 mm, following 60 minutes application time and to a depth of 3 mm following 120 minutes application time.
The effectiveness of Emla is independent of the color of the skin/pigmentation or the sin (skin types I-IV).
The use of Emla prior to measles-mumps-rubella or intramuscular diphtheria-pertussis-tetanus-inativated polio virus-Haemophilus influenzae B or Hepatitis B vaccines does not affect mean antibody titres, rate of seroconversion, or the proportion of patients achieving protective or positive antibody titres post immunization, as compared to placebo traeted patients.
Genital Mucosa
The time of onset of the necessary anaesthesia is shorter, as absorption is more rapid than with application to intact skin.
Following 5-10 minutes application of Emla to the genical mucosa in women, the anaesthetic effect against argon laser induced pain laster for 15-20 minutes (with an interindividual variation from 5-45 minutes).
Leg Ulcers
No negative effect on ulcer healing or bacterial flora has been observed. When cleaning leg ulcers Emla has analgesic effect for up to 4 hours after application.

Pharmacokinetics
The systemic absorption of Emla depends on the amount of cream, the application time, the thickness of the skin (which varies on different surfaces of the body) and the skin’s condition otherwise.
a) Intact Skin:
After application of 60 g Emla cream per 400 cm2 (1.5 g per 10 cm2) for three hours of intact skin (the thigh) in adults, systemic absorption was measured as 3% for lidocaine and 5% for prilocaine. Absorption takes place slowly. With the above mentioned dose, peak plasma concentrations for lidocaine (mean 0.12 mcg/ml) and prilocaine (mean 0.07 mcg/ml) were reached within approximately 4 hours after application. Only at levels of 5-10 mcg/ml are there risks of toxic symptoms.
Plasma levels of lidocaine and prilocaine in both geriatric and non-geriatric patients following application of Emla on intact skin are very low and well below potentially toxic levels.
b) Leg Ulcers:
After application to leg ulcers of 5-10 g Emla for 30 minutes peak plasma levels of lidocaine and prilocaine were reached after approximately 1-2.5 hours (for lidocaine within the range of 0.05-0.84 mcg/ml and for prilocaine 0.02-0.08 mcg/ml).
Following repeated application of Emla to leg ulcers there was no apparent accumulation in plasma of lidocaine, prilocaine or their metabolites. 2-10 g Emla was applied for 30-60 minutes to a maximal surface of 62 cm2, in total 15 times during a period of one month, 3-7 sessions a week.
c) Genital Mucosa:
After application of 10 g Emla cream to vaginal mucosa for 10 minutes, peak plasma concentrations were measured after approximately 35 minutes (mean values: lidocaine 0.18 mcg/ml, prilocaine 0.15 mcg/ml).

Indications:

Emla is indicated in:

  • Surface anesthesia of the skin in connection with needle insertion and for superficial surgical procedures
  • Surface anesthesia of leg ulcers prior to cleaning and superficial surgical procedures, for example removal of fibrin, pus and necroses
  • Surface anesthesia of the genital mucosa

Contraindicatons:

Hypersensitivity to local anesthetics of the amide type. Emla must not be used in premature infants (born before week 37 of pregnancy).

Drug Interactions:

The following interactions are to be noted:

  • Emla can potentiate the formation of methemoglobin in patients who are being treated with certain methaemoglobin-inducing preparations (e.g. sulpha preparations)
  • With high doses of Emla, the risk of additive systemic effects should be taken into account in patients who are given local anesthetics, e.g. tocainide
  • Specific interaction studies with lidocaine/prilocaine and anti-arrhythmic drugs call III (amiodarone) have not been performed, but caution is advised

Side Effects:

Adverse events with local anesthetics in the actual sense of the term occur in fewer than 1/1000 patients treated.

a) Common (>1/100):

  • Skin: Transient local reactions at the application site, such as paleness, redness, oedema

b) Less Common:

  • Skin: Initially a slight burning sensation, itching (at the application site)

c) Rare (<1/1000):

  • General: Allergic reactions, in the most severe cases anaphylactic shock. Methaemoglobinaemia in children.
  • Rare cases of discrete reactions at the application site, such as purpura or petechia, have been reported, especially following longer application times in children with atopic dermatitis or molluscs. Corneal irritation after accidental eye exposure.

Dosage and Administration:

1. Adults:
a) Leg Ulcers:

  • For cleaning of leg ulcers: approx. 1-2 g per 10 cm2. The cream is applied in a thick layer to the surface of the ulcer, but not more than 10 g per treatment procedure
  • Cover the surface of the ulcer with an occlusive dressing
  • An opened tube is intended for a single use, and any remaining cream must therefore be discarded after each treatment procedure.
  • Application time: at least 30 minutes
  • For leg ulcers with tissue that is particularly difficult to penetrate, the application time may be extended to 60 minutes
  • Cleaning of the ulcer should begin within 10 minutes after the cream has been removed
  • Emla has been used for up to 15 treatment procedures over a period of 1-2 months without a decline in effect or an increase in the number of local reactions

b) For Genital Use:

  • Use prior to injection of local anesthetics
  • Men: 1 ger per 10 cm2 . A thick later of cream is applied to the skin
  • Application time: 15 minutes
  • Women: 1-2 g per 10 cm2. A thick layer of cream is applied to the skin
  • Application time: 60 minutes

c) Genital Mucosa:

  • For removal of condyloma or prior to injection of local anesthetics: approx. 5-10 g, depending on the area to be treated
  • The whole surface, including the mucosal folds, must be covered. Occlusion is not necessary.
  • Application time: 5-10 minutes. The surgery must be begum immediately after removal of the cream

2. Children:
For needle insertion, curettage of the lesions caused by mollusca contagiosum and other minor surgical procedures: 1 g per 10 cm2.
A thick layer of cream is applied to the skin and covered with an occlusive dressing. The dose should not exceed 1 gram per 10 cm2 and must be adjusted according to the application area. A longer application time decreases the anesthesia.
Children with atopic dermatitis: reduce application time to 30 minutes.

Overdosage:

Systemic toxicity is very unlikely with normal use of Emla. In the event of toxicity, the symptoms are expected to be similar to those seen after local anesthesia treatment, i.e. excitatory CNS symptoms and in severe cases CNS and myocardial depression.
Rare cases of clinically significant methaemoglobinaemia in children have been reported. Prilocaine in high doses can increase the methaemoglobin level.
Topical administration of 125 mg prilocaine for 5 hours caused moderate methaemoglobinaemia in a 3-months-old-child. Topical administration of 8.6-17.2 mg/kg lidocaine caused very serious intoxication in infants.
Severe neurological symptoms (convulsions, CNS depression) require symptomatic treatment such as assisted ventillaton and anticonvulsant therapy.
In the event of methaemoglobinaemia methylthionium is the antidote. On the account of a slow systemic absorption, a patient with symptoms of toxicity should be kept under observation for several hours following any treatment of these symptoms.

Pregnancy and Lactation:

Pregnancy
Animal studies do not indicate direct or indirect harmful effects with respect to pregnancy, embryonal/foetal development, parturition or postnatal development. In both animal and humans, lidocaine and prilocaine corss the placental barrier and may be absorbed by the foetal tissue. It is reasonable to assume that lidocaine and prilocaine have been used in a large number of pregnant women and women of childbearing potential. No specific disturbances to the reproductive process have so far been reported, e.g. an increased incidence of malformations or other directly or indirectly harmful effects on the fetus. However, caution should be exercised with used in pregnant women.
Lactation
Lidocaine and prilocaine pass into the breast milk, but the risk of an effect on the child appears unlikely with therapeutic doses.

Warnings:

Patients with glucose-6-phosphate dehydrogenase deficiency or congenital or idiopathic methaemoglobinemia are more susceptibe to drug induced methaemologbinaemia.
Studies have been unable to demonstrate the efficacy of Emla for heel lancing in neonates.
Caution when using near the eyes, as Emla may cause eye irritation. Also, the loss of protective reflexes may allow corneal irritation and potential abrasion. If eye contact occurs, immediately rinse the eye in water or sodium chloride solution and protect untill sensation returns.
Caution when using on areas on skin with atopic dermatitis; the application time should be reduced (15-30 minutes).
In children under 2 months, safety and efficacy have only been studied with application of a single dose. In these children, a transient increase in methaemoglobin levels is often seen for up to 13 hours after Emla has been applied. However, the increase that have been observed are probably of no clinical significance.
Patients treated with anti-arrhythmic drugs class II (e.g. amiodarone) should be under close surveillance and ECG monitoring considered, since cardiac effects may be additive.
Emla should not be used on damaged tympanic membrane or in other situations where penetration into the middle ear may occur.
Emla should not be applied to open wounds.
Emla should not be used on the genital mucosa in children on account of incomplete data of absorption.
Lidocaine and prilocaine have bactericidal and antiviral properties in concentrations above 0.5-2%. For this reason the results of intracutaneous injections of live vaccines (e.g. BCG) should be monitored.
Until further clinical experience is available, Emla should not be used for children aged 0-12 months during concomitant treatment with methaemoglobin-inducing drugs (see also Overdose).

Storage:

Store at room temperature, below 25°C.

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