Local Anesthetics

Question 1

What is the most widely used anaesthetic?

Answer 1

Lidocaine

Question 2

What local anaesthetic is cardiotoxic?

Answer 2

Bupivacaine

Question 3

Which local anaesthetic is contraindicated in obstetric anaesthesia?

Answer 3

Mepivacaine

Question 4

Why is Mepivacaine contraindicated in obstetric anesthesia?

Answer 4

Due to its increased toxicity to neonates

Question 5

What is the clinical use of local anaesthetics?

Answer 5

Complete loss of sensory modalities

Analgesia

Question 6

What is the target of local anaesthetics?

Answer 6

Inactivated voltage gated sodium channels

Question 7

What part of the voltage gated sodium channel do local anaesthetics bind to?

Answer 7

The IC part

Question 8

Which drugs bind to the EC part of the activated voltage gated sodium channel?

Answer 8

Tetrodotoxin

Saxitotoxin

Question 9

What are the three states of the voltage gated sodium channel?

Answer 9

Resting state
Inactivation state
Activation state

Question 10

What are the M and H gate doing during resting state?

Answer 10

M gate is closed

H gate is open

Question 11

What are the M and H gate doing during the activation state?

Answer 11

Both gates are open

Question 12

What are the M and H gate doing during the inactivation state?

Answer 12

The M gate is open

The H gate is closed

Question 13

What is the M gate?

Answer 13

The activation gate

Question 14

What is the H gate?

Answer 14

The inactivation gate

Question 15

What are the methods of administration of local anaesthetics?

Answer 15

Surface
Infiltration
IV
Peripheral nerve blocks
Spinal
Epidural

Question 16

What is the order of disappearance of sensations?

Answer 16

1. Pain
2. Temperature
3. Touch
4. Deep pressure
5. Motor function

Question 17

What nerve fibres are most sensitive to blockage?

Answer 17

Nerve fibres off small diameter and high firing rates

Question 18

What is the order of sensitivity of the nerve fiber types?

Answer 18

Type B and C
A delta
A beta and gamma
A alpha

Question 19

What are the CNS side effects of local anaesthetics?

Answer 19

Headache
Sleepiness
Visual and auditory disturbances 
Restlessness
Nystagmus 
Shivering
Muscular twitching
Seizures 
Depression
Death
Cocaine: feeling of well being, psychostimulant, euphoria

Question 20

What are the cardiovascular side effects of local anaesthetics?

Answer 20

Depression of pacemaker activity, condition, excitability, contractility
Vasodilation - hypotension
Cocaine: vasoconstriction

Question 21

Why is a side effect of local anaesthetics allergies?

Answer 21

Esters viva PABA formation

Sulfonamides are esters of PABA

Question 22

What are the haematological side effects of local anaesthetic use?

Answer 22

Prilocaine can result in methemoglobinemia

Question 23

Can local anaesthetics cross the placenta?

Answer 23

Local anaesthetics may cross the placenta

Question 24

What are the (broad) side effects of local anasthetic use?

Answer 24

CNS effects
Cardiovascular toxicity 
Allergies
Haematological effects
Local anaesthetics may cross the placenta

Question 25

What is Ropivacaine metabolised by?

Answer 25

CYP1A2

Question 26

What enzyme is Lidocaine and Bupoivacaine metabolised by?

Answer 26

CYP3A4

Question 27

What are the general categories of LI?

Answer 27

Esters and amides

Question 28

Name the ester LA?

Answer 28

Procaine Cocaine Benzocaine

Question 29

Name the amide LA?

Answer 29

``` Lidocaine Prilocaine Bupivacaine Ropivacaine Mepivacaine Atricaine ```

Question 30

What are the esters metabolised by?

Answer 30

Plasma and tissue esterases

Question 31

What are the amides metabolised by?

Answer 31

Liver amidases

Question 32

What is the potency of procaine?

Answer 32

1

Question 33

What is the potency of bupivacaine?

Answer 33

16

Question 34

What is the potency of Mepivacaine?

Answer 34

2

Question 35

What is the potency of Atricaine?

Answer 35

10

Question 36

Which LA is the most potent?

Answer 36

Bupivacaine

Question 37

Which LA is the least potent?

Answer 37

Procaine

Question 38

Which LA have a short duration of action?

Answer 38

Procaine | Atricaine

Question 39

Which LA have a medium duration of action?

Answer 39

Cocaine Lidocaine Prilocaine Mepivacaine

Question 40

Which LA have a long duration of action?

Answer 40

Benzocaine Bupivacaine Ropivacaine

Question 41

Which LA have poor tissue penetration?

Answer 41

Procaine

Question 42

Which LA have moderate tissue penetration?

Answer 42

Prilocaine Bupivacaine Ropivacaine

Question 43

Which LA have good tissue penetration?

Answer 43

Cocaine Lidocaine Mepivacaine Atricaine

Question 44

What is the clinical indication of procaine?

Answer 44

No longer used

Question 45

What is the clinical indication of cocaine?

Answer 45

Rarely used. Only as a spray for upper respiratory tract

Question 46

What is the clinical use of Benzocaine?

Answer 46

Surface anesthesia

Question 47

What is the clinical use of lidocaine?

Answer 47

Local anaesthesia but also IV for treating ventricular dysrhythmias

Question 48

What is the clinical use of prilocaine?

Answer 48

Spinal anesthesia | Not used for obstetric analgesia

Question 49

What is the clinical use of Ropivacaine?

Answer 49

Spinal anesthesia | Not used for obstetric analgesia

Question 50

What is the clinical use of Mepivacaine?

Answer 50

Infiltration and nerve block anesthesia Mild vasoconstrictor effect Not used in babies or small children

Question 51

What is the clinical use of Atricaine?

Answer 51

Infiltration and nerve block anesthesia More lipophillic Used in dentistry

Question 52

What are the cardiovascular side effects of procaine?

Answer 52

Bradycardia and vasodilation

Question 53

What are the adverse CNS effects of procaine?

Answer 53

Restlessness Convulsions Respiratory depression

Question 54

What are the adverse effects of prilocaine?

Answer 54

No vasodilator activity | Less risk of systemic toxicity but risk of methemoglobinemia