Local anesthetics - sather

Question 1

Lidocaine what type of drug?

Answer 1

Amide local anesthetic.

Question 2

what type of drug is Bupivacaine?

Answer 2

Amide local anesthetic.

Question 3

*Bupivacaine

Answer 3

Amide local anesthetic.

Question 4

With regard to nomenclature of local anesthetics, how can one differentiate between esters and amides?

Answer 4

Esters have one “i” (procaine)

Amide have two “i” (lidocaine)

Question 5

What is the relative sensitivity of the C, adelta, aalpha, and abeta fibers to block by lidocaine?

Answer 5

C > adelta > aalpha = abeta

Question 6

What is the relative potency of procaine, lidocaine, and bupivacaine?

What three factors determine the efficacy of a local anesthetic?

Answer 6

bupivacaine > lidocaine > procaine

Lipid solubility
Lower pKa (faster speed of onset due to increased proportion are uncharged, hence can cross membranes)
Greater protein binding (longer half life)

Question 7

List procaine, bupivacaine, and lidocaine in order of half life.

Answer 7

Bupivacaine > Lidocaine > procaine

**correlates with protein binding. Amides bind more than esters.

Question 8

Which LA is employed in an intravenous regional block (eg tourniquet)?

Answer 8

Lidocaine.

Question 9

What effect do local anesthetics have on blood vessels?

Answer 9

Vasodilation. For this reason they are often administered with epinephrine.

Question 10

Ester LAs are metabolized where?

Amides?

Answer 10

Esters - pseudocholinesterase (systemic) and liver

Amide - liver only

Question 11

Allergies to LAs are rarely seen. But, which is more likely to cause an allergy, amide or ester?

Answer 11

Ester are more likely to cause an allergic reaction.

Ester –> IgE mnemonic