Answer:
Local anesthesia...
1) produces a blockade of excitation at nerve endings or...
2) inhibits the process of conduction in peripheral nerve tissue and...
3) inhibits individual sodium channels and reduces the composite inward sodium current of the nerve fiber, also...
4) binding site is not specifically known.
5) Nerve impulses are blocked by local anesthetics that inhibit voltage-gated sodium channels. Local anesthetics inhibit these channels by interfering with the configuration changes underlying the activation process as channels go from a closed (resting) state to an open (conducting ) one.
Amino esters vs Amino amides:
Three basic differences...
1) metabolism
2) stability in solution
3) potential for allergic reaction
Esters (tetracaine, novacaine, cocaine, benzocaine)...
1) degrade in plasma via pseudocholinesterase
2) unstable in solution
3) more capable of causing allergy
Amides (lidocaine, mepivicaine, prilocaine, bupivicaine - all have 'i' in the name before 'caine' suffix)...
1) degraded in the liver
2) stable in solution
3) allergic reaction are extremely rare