Is EMLA (lidocaine and prilocaine) cream the same as other topical creams, such as hydrocortisone cream?

EMLA Cream vs. Other Topical Creams

EMLA cream is not the same as other topical creams such as hydrocortisone cream. EMLA is a eutectic mixture of local anesthetics (lidocaine 2.5% and prilocaine 2.5%) specifically designed for topical anesthesia, while hydrocortisone is a corticosteroid used to reduce inflammation.

Composition and Mechanism of Action

• EMLA cream contains:

  • Lidocaine 2.5%
  • Prilocaine 2.5%
  • Formulated as an oil-in-water emulsion 1

• Mechanism of action:

  • Both lidocaine and prilocaine are amide-type local anesthetics
  • They stabilize neuronal membranes by inhibiting ionic fluxes required for impulse initiation and conduction
  • The eutectic mixture allows both anesthetics to be liquid at room temperature, enhancing skin penetration 1

Clinical Uses

EMLA cream is indicated for:

• Local analgesia on normal intact skin 1
• Anesthesia of genital mucous membranes for superficial minor surgery 1
• Pretreatment for infiltration anesthesia 1
• Prevention of pain from needle punctures or incisions 2
• Management of pain associated with venipuncture or intravenous cannulation 3
• Dermatological procedures like curettage of molluscum contagiosum lesions and split-skin graft harvesting 3

In contrast, hydrocortisone cream is used for:

• Inflammatory skin conditions 2
• Treatment of xerotic skin reactions 2
• Management of inflammatory lesions 2

Application and Onset

• EMLA requires:

  • Application under occlusive dressing for at least 1 hour for procedures like intravenous catheter placement
  • At least 2 hours for procedures like split-skin graft harvesting
  • Satisfactory dermal analgesia is achieved 1 hour after application, reaches maximum at 2-3 hours, and persists for 1-2 hours after removal 1
  • Faster onset (5-10 minutes) when applied to genital mucosa 1

• In comparison, hydrocortisone and other topical anti-inflammatory creams:

  • Do not provide anesthesia
  • Work by reducing inflammation rather than blocking nerve impulses
  • May take days to show full therapeutic effect 2

Contraindications and Precautions

EMLA cream should not be used in:

• Patients with allergy to amide anesthetics
• Non-intact skin
• Patients with congenital or idiopathic methemoglobinemia
• Infants aged <12 months receiving treatment with methemoglobin-inducing agents 4
• Near the eyes or on open wounds 1
• When penetration beyond the tympanic membrane is possible due to ototoxic effects 1

Safety Considerations

• EMLA can cause methemoglobinemia, a serious condition requiring prompt treatment 1

• Risk factors for systemic toxicity include:

  • Excessive amount of EMLA
  • Large application area
  • Prolonged application time
  • Diseased or inflamed skin
  • Age less than 3 months
  • Prematurity
  • Concomitant use of methemoglobin-inducing agents 5

• EMLA should be used with caution in:

  • Acutely ill, debilitated, or elderly patients
  • Patients with severe hepatic disease 1
  • Patients receiving Class I antiarrhythmic drugs 1

Efficacy Comparison

Research shows that EMLA is superior to other topical anesthetics:

• In a randomized comparative trial, EMLA demonstrated better efficacy than 10% lidocaine cream regarding anesthesia onset and duration 6
• For acceptable pain at 4-mm depth, EMLA required 40.88 minutes of application compared to 45.38 minutes for 10% lidocaine 6

Clinical Implications

When choosing between EMLA and other topical creams:

1. Consider the primary goal:

   • For anesthesia/pain control: EMLA is appropriate
   • For inflammation: Hydrocortisone or other corticosteroid creams

2. Consider application time:

   • EMLA requires 1-2 hours under occlusive dressing for full effect
   • Hydrocortisone may require days of regular application

3. Consider safety profile:

   • EMLA has risks of methemoglobinemia and systemic toxicity
   • Hydrocortisone has risks of skin thinning with prolonged use

4. Consider the specific procedure:

   • For needle procedures, minor surgeries: EMLA is preferred
   • For inflammatory skin conditions: Hydrocortisone is preferred

In summary, EMLA cream and hydrocortisone cream are fundamentally different medications with distinct mechanisms of action, indications, and safety profiles.