What is the shared mechanism of action for bupivacaine and lidocaine?

What is the shared mechanism of action for bupivacaine and lidocaine?

• A. Ca2+ channel blocker
• B. GABA receptor agonist
• C. Voltage-gated sodium channel blocker
• D. Na+ channel blocker

Answer: (D)

Local anesthetics numb tissue by stopping nerve impulses. They do this by blocking sodium entry through voltage-gated Na+ channels in the nerve membrane. When lidocaine or bupivacaine enters the axon, they bind to the channel and stabilize its inactivated state, preventing the channel from reopening. Without sodium influx, the action potential cannot propagate, so pain signals aren’t carried to the brain. Describing the shared mechanism as a Na+ channel blocker captures this essential effect for both drugs. In the nervous system, those Na+ channels are voltage-gated, so blocking Na+ channels effectively means blocking the voltage-gated sodium channels involved in impulse transmission. The other options point to mechanisms that don’t explain how these local anesthetics prevent nerve conduction.

Local anesthetics numb tissue by stopping nerve impulses. They do this by blocking sodium entry through voltage-gated Na+ channels in the nerve membrane. When lidocaine or bupivacaine enters the axon, they bind to the channel and stabilize its inactivated state, preventing the channel from reopening. Without sodium influx, the action potential cannot propagate, so pain signals aren’t carried to the brain.

Describing the shared mechanism as a Na+ channel blocker captures this essential effect for both drugs. In the nervous system, those Na+ channels are voltage-gated, so blocking Na+ channels effectively means blocking the voltage-gated sodium channels involved in impulse transmission. The other options point to mechanisms that don’t explain how these local anesthetics prevent nerve conduction.