Which drug listed is a CRI analgesia option that also functions as a local anesthetic?

• A. Opioid
• B. Ketamine
• C. Dexmedetomidine
• D. Lidocaine

Answer: (D)

The key idea is that some drugs can provide analgesia systemically when given as a continuous-rate infusion and also act as local anesthetics by blocking nerve conduction. Lidocaine does this because it blocks voltage-gated sodium channels, which suppresses pain signaling in the body when given systemically, and also prevents nerve depolarization when used locally to infiltrate or apply to an area, producing local numbness.

As a CRI, lidocaine reduces peripheral nerve excitability, may dampen inflammatory mediators, and can lower overall analgesic requirements after surgery. Locally, its sodium-channel blockade stops action potentials in nerves, giving a reversible loss of sensation in the targeted region.

The other drugs don’t have local anesthetic properties. An opioid provides systemic pain relief via opioid receptors but doesn’t numb tissue locally. Ketamine offers analgesia through NMDA receptor antagonism and other pathways, not by blocking sodium channels. Dexmedetomidine provides analgesia and sedation through alpha-2 receptor effects but lacks local anesthetic action.

So lidocaine is the one that fits both roles.