Which choice is an injectable local anesthetic?

Which choice is an injectable local anesthetic?

• A. Ophthaine®
• B. EMLA® cream
• C. Xylocaine®
• D. Isoflurane

Answer: (C)

Understanding local anesthetics means recognizing how they work and how they’re delivered. Injectable local anesthetics, like lidocaine, act by blocking voltage-gated sodium channels on nerve fibers, which stops the nerves from firing and prevents pain signals from reaching the brain. This effect is localized to the area where the drug is placed, and the anesthesia wears off as the drug is metabolized. Xylocaine contains lidocaine and is formulated for injection, making it suitable for local infiltration or nerve blocks. The other options are not injectable local anesthetics: Ophthaine is used as eye drops for topical corneal anesthesia; EMLA cream is a topical cream (a mixture of lidocaine and prilocaine) for skin surface anesthesia; Isoflurane is an inhaled general anesthetic used to render a patient unconscious rather than provide local numbness.

Understanding local anesthetics means recognizing how they work and how they’re delivered. Injectable local anesthetics, like lidocaine, act by blocking voltage-gated sodium channels on nerve fibers, which stops the nerves from firing and prevents pain signals from reaching the brain. This effect is localized to the area where the drug is placed, and the anesthesia wears off as the drug is metabolized.

Xylocaine contains lidocaine and is formulated for injection, making it suitable for local infiltration or nerve blocks. The other options are not injectable local anesthetics: Ophthaine is used as eye drops for topical corneal anesthesia; EMLA cream is a topical cream (a mixture of lidocaine and prilocaine) for skin surface anesthesia; Isoflurane is an inhaled general anesthetic used to render a patient unconscious rather than provide local numbness.