VPT 321: Veterinary Neuropharmacology (2+1)

CHEMISTRY OF LOCAL ANAESTHETICS

Local anaesthetics are divided chemically into two groups:

• Lengthening of intermediate chain or addition of Carbon atoms in the amine or aromatic increase in potency
• Addition of butyl group to the amine or aromatic end → lipid solubility, protein binding → increased potency and long action

Features of Amide LAs

• More intense and longer lasting anaesthesia
• Bind to plasma protein ( α₁ acid glycoprotein)
• Not hydrolysed by plasma esterases
• Rarely cause hypersensitivity
• Ester type LAs – cocaine, procaine, chloroprocaine, tetracaine, benzocaine
• Amide type LAs – lidocaine (lignocaine), bupivacaine, dibucaine, prilocaine