Which statement about allergic reactions to local anaesthetics is correct?

• A Amide agents are more allergenic because they are protein bound
• B Ester agents are more allergenic because they are metabolised to para-aminobenzoic acid ✓
• C True IgE-mediated allergy is common and accounts for most adverse reactions
• D Cross-reactivity occurs between all ester and amide agents

Explanation

Ester local anaesthetics undergo hydrolysis by plasma pseudocholinesterase to para-aminobenzoic acid, a known hapten responsible for most true allergic reactions to local anaesthetics. Amides are metabolised in the liver and do not produce PABA, making genuine allergy to them exceedingly rare. Most perioperative 'allergic' reactions are actually vasovagal episodes, adrenaline effects, or toxicity from inadvertent intravascular injection. Cross-reactivity within the ester group occurs via shared PABA metabolites, not between classes.

Reference: Katzung's Basic and Clinical Pharmacology, 16th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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