EMLA is a mixture of lidocaine and:
**Core Concept**
EMLA (Eutectic Mixture of Local Anesthetics) is a topical anesthetic cream used to numb the skin before minor procedures. It works by inhibiting sodium channels in nerve fibers, preventing the generation and conduction of action potentials.
**Why the Correct Answer is Right**
EMLA is a mixture of two local anesthetics: lidocaine and prilocaine. The combination of these two agents enhances the potency and duration of analgesia, making EMLA an effective and versatile anesthetic cream. The eutectic mixture of lidocaine and prilocaine creates a solution with a lower melting point than either agent alone, allowing for easier absorption through the skin and more efficient delivery of the anesthetics.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because EMLA does not contain bupivacaine, a long-acting local anesthetic that is not typically used in topical formulations due to its potential for toxicity.
**Option B:** This option is incorrect because EMLA does not contain tetracaine, a local anesthetic that is not commonly used in topical creams due to its potential for irritation and toxicity.
**Option C:** This option is incorrect because EMLA does not contain mepivacaine, a local anesthetic that is not typically used in topical formulations due to its limited potency and duration of action.
**Clinical Pearl / High-Yield Fact**
When using EMLA, it's essential to apply the cream 1-2 hours before the procedure to allow for adequate absorption and onset of analgesia. Additionally, EMLA should be avoided in patients with severe hepatic dysfunction, as prilocaine is metabolized by the liver and can accumulate to toxic levels in patients with impaired liver function.
**Correct Answer:** D. prilocaine