Local anaesthetic pharmacology

Stimulus

You are shown a table of common local anaesthetics with five columns: class (amide or ester), pKa, lipid solubility (partition coefficient), protein binding (per cent) and approximate duration of action. Representative entries might read: lidocaine (amide, pKa about 7.9, moderate lipid solubility, about 65 per cent bound, 1 to 2 hours); bupivacaine (amide, pKa about 8.1, high lipid solubility, about 95 per cent bound, 4 to 8 hours); ropivacaine (amide, pKa about 8.1, intermediate lipid solubility, about 94 per cent bound, 4 to 6 hours); prilocaine (amide, pKa about 7.9, moderate lipid solubility, about 55 per cent bound, 1 to 2 hours); procaine (ester, pKa about 8.9, low lipid solubility, about 6 per cent bound, 0.5 to 1 hour); chloroprocaine (ester, pKa about 9.0, low lipid solubility, low protein binding, 0.5 to 1 hour); amethocaine (ester, pKa about 8.2, high lipid solubility, high protein binding, 2 to 3 hours).