LA Potency Lipid Solubility — NDEB AFK MCQ
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Correct answer: D — Lipid solubility
Lipid solubility (lipophilicity) is the primary determinant of local anaesthetic potency. Local anaesthetics must penetrate the lipid-rich nerve cell membrane to reach their intracellular binding site on the sodium channel. Higher lipid solubility means greater membrane penetration and lower concentration needed for nerve blockade (higher potency). Bupivacaine is the most lipid-soluble (and most potent) commonly used dental LA. Protein binding determines duration of action (higher binding = longer duration). pKa determines onset speed (closer to physiological pH = faster onset).
Reference: Malamed – Handbook of Local Anesthesia, 7th ed., 2020