19. ester amides hydrophobic hydrophilic Molecule linkage is more easily broken less Less stable More stable- longer stored Not heat-stable- cant Heat-stable- can be autoclave Metabolism mostly produces PABA >allergic reaction rare Short duration of action longer Rarely used Commonly used Eg: chloroprocaine cocaine dimethocaine procaine tetracaine/amethocaine Eg: bupivacaine cinchocaine/dibucaine levobupivacaine lidocaine/lignocaine mepivacaine prilocaine ropivacaine