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Procaine PABA Allergy — NDEB AFK MCQ

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ModeratePharmacologyProcaine PABA AllergyNDEB AFK

Which of the following local anaesthetic agents is most commonly associated with allergic reactions due to its metabolite para-aminobenzoic acid (PABA)?

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Correct answer: B — Procaine

Procaine is an ester-type local anaesthetic that is hydrolysed by plasma cholinesterase to produce para-aminobenzoic acid (PABA), a known allergen. PABA cross-reacts with other PABA-containing compounds (sulfonamides, certain sunscreens, hair dyes). True allergic reactions to amide local anaesthetics (lidocaine, mepivacaine, articaine, bupivacaine, prilocaine) are exceedingly rare (<1% of reported reactions). Most reported 'allergic' reactions to dental LA are actually psychogenic (vasovagal syncope) or reactions to the preservative (methylparaben, structurally similar to PABA).

Reference: Malamed – Handbook of Local Anesthesia, 7th ed., 2020