Local Anesthetics

Question 1

Drugs which upon topical application or local injection cause reversible loss of sensory perception especially of pain in a restricted area of the body?

Answer 1

Local anesthetics (LA).

Question 2

LAs block nerve conduction of ________ impulses and in higher concentration blocks ______ Impulses.

Answer 2

Sensory,
Motor.

Question 3

Which fibers are most susceptible to LA?

Answer 3

Type B fibers (pre-ganglionic autonomic fibers), and type C fibers (carrying pain).

Question 4

List the 2 classifications of LA?

Answer 4

1- injectable anesthetics.
2- surface anesthetics.

Question 5

List the 3 types of injectable anesthetics?

Answer 5

1- low potency, short duration.
2- intermediate potency and duration.
3- high potency, long duration.

Question 6

List the 2 types of surface anesthetics?

Answer 6

1- soluble.
2- insoluble.

Question 7

Give examples of injectable anesthetics with low potency, and short duration?

Answer 7

1- procaine.
2- chloroprocaine.

Question 8

Give examples of injectable anesthetics with intermediate potency and duration?

Answer 8

1- lidocaine (lignocaine).
2- prilocaine.

Question 9

Give examples of injectable anesthetics with high potency and long duration?

Answer 9

1- tetracain (amethocaine).
2- bupivacaine.
3- ropivacaine.
4- dibucaine (cinchocaine).

Question 10

Give examples of surface anesthetics that are soluble?

Answer 10

1- cocaine.
2- lidocaine.
3- tetracaine.
4- benoxinate.

Question 11

Give examples of surface anesthetics that are insoluble?

Answer 11

1- benzocaine.
2- oxethazaine.

Question 12

Which drug is the only naturally occurring LA?

Answer 12

Cocaine.

Question 13

Why is cocaine not used clinically?

Answer 13

Because of its adverse effects and abuse potential.

Question 14

All LAs (other than cocaine) are ________ derived?

Answer 14

Synthetically.

Question 15

list ester-linked LAs

Answer 15

(one I)
1- cocaine
2- procaine.
3-chloroprocaine.
4- tetracaine.
5- benzocaine.

Question 16

list amide- linked LAs

Answer 16

(two Is)
1- lidocaine.
2- bupivacaine.
3- dibucaine.
4- prilocaine.
5- ropivacaine.

Question 17

which LA produces more intense and longer lasting anesthesia?

Answer 17

amide LA.

Question 18

which LA rarely cause hypersensitivity reactions?

Answer 18

amide LA.

Question 19

local anesthetics are _______

Answer 19

weak bases.

Question 20

the relative proportion of these two forms is governed by?

Answer 20

1- their pKa.
2- pH of the body fluids.

Question 21

which for of LA is lipid-soluble and can enter nerve cell membrane?

Answer 21

non-ionized form.

Question 22

LAs can interact with a receptor situated ____ the voltage sensitive Na+ channel?

Answer 22

within

Question 23

the active species is the ionic form of the LA which able to reach the receptor only when?

Answer 23

the channel is open at the inner face.

Question 24

binding of LA prolongs what?

Answer 24

the inactivated state.

Question 25

adrenaline should not be co-administered for nerve block where? why? and what do we use instead?

Answer 25

in fingers and toes. vasoconstriction of end arteries can lead to ischemia and necrosis. we use ring block instead.

Question 26

All LAs are cardiac _____

Answer 26

depressants.

Question 27

LA can induce cardiac ______

Answer 27

arrhythmias.

Question 28

which LA is cardiotoxic?

Answer 28

bupivacaine.

Question 29

which LAs are used as anti-arrhythmics?

Answer 29

lignocaine and procainamide.

Question 30

list the 5 uses and techniques of LA?

Answer 30

1-surface anesthesia. 2- infiltration anesthesia. 3- conduction anesthesia. 4- spinal anesthesia. 5- epidural anesthesia.

Question 31

which LAs are capable of anesthetizing intact skin?

Answer 31

eutectic lidocaine/ prilocaine.

Question 32

what are the uses of surface anesthesia?

Answer 32

ocular tonometry. intubation. endoscopic procedures.

Question 33

which LAs are used during ocular tonometry, intubation, and endoscopic procedures.

Answer 33

tetracaine and lignocaine.

Question 34

which LAs are combined to make EMLA?

Answer 34

lidocaine, prilocaine.

Question 35

EMLA is commonly used for which age group?

Answer 35

peds

Question 36

infiltration anesthesia is used for what?

Answer 36

minor operations

Question 37

which LAs are commonly used as infiltration anesthesia?

Answer 37

lignocaine and bupivacaine.

Question 38

list the 2 types of conduction block?

Answer 38

1- field block. 2- nerve block.

Question 39

field block is commonly done for what?

Answer 39

herniorrhaphy, appendicectomy, dental procedures, scalp stitching, operations on forearms and legs.

Question 40

nerve block is used for what?

Answer 40

lingual, intercostal,ulnar, sciatic, femoral, brachial plexus, trigeminal, facial, phrenic.

Question 41

what is the advantage of nerve block?

Answer 41

even with a small amount of drug, a large area can be anesthetized.

Question 42

spinal anesthesia is used for which procedures?

Answer 42

operations on the lower limbs, pelvis and lower abdomen.

Question 43

which LAs are used in spinal anesthesia?

Answer 43

lignocaine, bupivacaine.

Question 44

in spinal anesthesia LA is injected where?

Answer 44

subarachnoid space between L2-3 OR L3-4

Question 45

primary site of action of spinal anesthesia is?

Answer 45

nerve roots in the cauda equina.

Question 46

what are the complications of spinal anesthesia?

Answer 46

1- hypotension. 2- headache. 3- septic meningitis. 4- nausea and vomiting. 5- cauda equina syndrome.

Question 47

which LA is used in epidural anesthesia?

Answer 47

lignocaine and bupivacaine.