Local Anesthetics And Muslce Relaxants (Lauren 🌭)

Question 1

What is infiltration anesthesia?

Answer 1

Injection of the local anesthetic into the tissue

Advantage: anesthesia without disrupting normal body function (for the most part)

Disadvantage: requires large amounts of drug

Question 2

Local anesthetics can be esters or amides. Which type has a shorter duration of action?

Answer 2

Esters

Question 3

Which type of local anesthetic has more systemic toxicity: esters or amides?

Answer 3

Esters

Question 4

Local anesthetics are weak (acids/bases)

Answer 4

Bases

Question 5

At physiological pH, local anesthetics are mostly (ionized/non-ionized)

Answer 5

Ionized

But the closer to physiological pH, the more LA can be non-ionized so that it can cross the membrane

Question 6

Where do local anesthetics need to bind to nerve cells to have an effect?

Answer 6

Inner membrane, plugging up the Na+ channels

Question 7

Local anesthetics need to be in the (ionized/non-ionized) form to cross the cell membrane and get inside the nerve cells

Answer 7

Non-ionized

Question 8

How do local anesthetics inhibit action potentials and neuron firing?

Answer 8

They plug up Na+ channels from the inside, which prevents

membrane depolarization and therefore, action potentials

Question 9

When local anesthetics plug up the Na+ channels from the inside, they are in the (ionized/non-ionized form)

Answer 9

Ionized

Question 10

The closer the pKa of an anesthetic is to 7.4, the higher the concentration of it will be in the (ionized/non-ionized) form

Answer 10

Non-ionized

Which means it can cross the cell membrane faster and kick in faster

Question 11

Which will have a faster onset of action: Lidocaine (pKa 7.8) or bupivacaine (pKa 8.1)

Answer 11

Lidocaine

Question 12

What is the exception to the rule regarding being in the ionized vs non-ionized form based on the pH

Answer 12

Benzocaine (pKa 3.5), it is ALWAYS in the non-ionized form

Question 13

How come benzocaine can only be applied topically?

Answer 13

Because it is ALWAYS in the non-ionized form no matter what.

Question 14

Inflammation/infection will (increase/decrease) membrane transport

Answer 14

Decrease

Inflammation= acidic=need more drug

Question 15

What effect will adding bicarbonate to the local anesthetic have?

Answer 15

It will make the pH more basic and more of the anesthetic will be in the non-ionized form, so more of it can get across the cell membrane

Question 16

What is the mechanism of action of local anesthetics?

Answer 16

Blocks voltage gated Na+ channels= no action potentials, no firing of neurons

Question 17

What effect will elevated extracellular calcium have on local anesthetic effect?

Answer 17

Hyperpolarizes the membrane, causes more Na+ channels to be in the resting state, and the block is diminished

Question 18

What effect will elevated extracellular K+ have on the effect of local anesthetic?

Answer 18

It depolarizes the membrane, so more of the channels will be in the inactivated state, and the block is enhanced

Question 19

Local anesthetics have a high affinity for channels in what states?

Answer 19

Activated (open) and inactivated states

Question 20

Local anesthetics have a LOW affinity for sodium channels in what state?

Answer 20

Resting (closed) state

Question 21

Increased lipid solubility will (increase/decrease) the duration of action of a local anesthetic

Answer 21

Increase

Question 22

Procaine has a ________ duration of action

Answer 22

Short

Shortest of all of them. It is the standard that all of the others are relative to

Question 23

Cocaine, Mepivacaine, and Lidocaine have a _________ duration of action

Answer 23

Medium

Question 24

Tetracaine, Bupivacaine, and Ropivacaine have a _______ duration of action

Answer 24

Long

Question 25

The duration of action for a local anesthetic is dependent on (half life/time at site)

Answer 25

time at site

Question 26

The systemic toxicities of local anesthetics are dependent on (half life/time at site)

Answer 26

Half life

Question 27

True or false: The duration of action of a local anesthetic is dependent on its half life

Answer 27

FALSE | Time at site

Question 28

What factors will affect how much a local anesthetic will be systemically absorbed?

Answer 28

Dosage Site of injection (vascular area vs fat) Drug-tissue binding Chemical properties of drug Local blood flow Vasoconstricing agents (epinephrine)

Question 29

Why do we add epinephrine to many local anesthetics?

Answer 29

Its a vasoconstrictor, which: Decreases diffusion of drug Prolongs duration of action Decreases systemic absorption Decreases risk of systemic toxicity

Question 30

Most local anesthetics are vaso (constrictors/dilators)

Answer 30

Vasodilators | Except for Ropivacaine

Question 31

How are LA’s that are amides metabolized?

Answer 31

In the liver by CYP450’s

Question 32

Which type of LA would be bad for someone with a shitty liver: Amide or Ester

Answer 32

Amide | Metabolized in liver

Question 33

How are LA’s that are esters metabolized?

Answer 33

Rapidly metabolized by butyrylcholinesterases in the plasma

Question 34

What can affect how quickly someone metabolizes an ester local anesthetic?

Answer 34

Mutations in the butyrylcholinesterase enzymes

Question 35

What is a differential block?

Answer 35

The block is not limited to the intended site: pain is blocked, but motor nerves are too. Can cause paralysis, respiratory impairment, and hypotension

Question 36

Bupivacaine will hit (sensory/motor) neurons first

Answer 36

Sensory

Question 37

Etidocaine will hit (motor/sensory) neurons first

Answer 37

Motor This is called an inverse differential block. Paralyzed but still feeling pain. FUN!

Question 38

In general, what is the order that neuron types are affected by LA’s?

Answer 38

Sympathetic Sensory (pain) Touch Motor

Question 39

Which type of nerve fibers are more sensitive to LA’s: Small diameter or Large diameter

Answer 39

Smaller diameter

Question 40

Which type of nerve fiber is more sensitive to LA’s: | Myelinated or Unmyelinated

Answer 40

Unmyelinated

Question 41

The faster that a nerve fiber conducts, the (more/less) sensitive it is to LAs

Answer 41

Less | Slow conducting neurons are more sensitive

Question 42

LAs will affect myelinated, fast conducting, large diameter neurons last or not at all. Which types of neurons have these properties?

Answer 42

Motor neurons Neurons that detect pressure and temperature (The ones that don’t usually get affected by LAs)

Question 43

LAs will affect small, Unmyelinated, slow-conducting nerve fibers the most. Which nerve fiber types have these properties and will be the most sensitive to LAs?

Answer 43

Pain

Question 44

Which local anesthetic has the most cardiac toxicity?

Answer 44

Bupivacaine

Question 45

Which type of local anesthetic is most likely to cause hypersensitivity: esters or amides

Answer 45

Esters | Allergic reactions RARE with amides

Question 46

Which local anesthetics has a metabolite that may produce methemoglobinemia?

Answer 46

Prilocaine

Question 47

Why is lidocaine not recommended for spinal anesthesia?

Answer 47

Can cause transient neurological symptoms: pain and dysesthesia (tingling)

Question 48

In general, older anesthetics are (amides/esters) and newer ones are (amides/esters)

Answer 48

Older: esters Newer: amides

Question 49

Ester or amide: Procaine

Answer 49

Ester

Question 50

What is the duration of action of procaine?

Answer 50

SHORT

Question 51

What are the two uses for procaine?

Answer 51

Infiltration anesthesia (short procedures) Diagnostic nerve blocks

Question 52

If youre going to get a colonoscopy and the doctor wants to numb up your booty hole for a short period of time, which local anesthetic would be good for this?

Answer 52

Procaine

Question 53

Which anesthetic would be good for diagnostic nerve blocks?

Answer 53

Procaine

Question 54

Ester or amide: Tetracaine (Pontocaine)

Answer 54

Ester

Question 55

Which anesthetic is 16x more potent and more toxic than procaine?

Answer 55

Tetracaine (Pontocaine)

Question 56

Which anesthetic is preferred for ophthalmological use (retrobulbar anesthesia)

Answer 56

Tetracaine (Pontocaine)

Question 57

Can Tetracaine (Pontocaine) be used for spinal anesthesia?

Answer 57

Yes, when combined with dextrose it becomes heavier than the CSF

Question 58

Ester or amide: Benzocaine (Americaine)

Answer 58

Ester

Question 59

Benzocaine is (very/not at all) lipophilic

Answer 59

Very

Question 60

Benzocaine is always in WHAT form

Answer 60

Non-ionized (since its pKa is only 3.5)

Question 61

What anesthetic is ONLY used topically for sunburns, minor burns and itching?

Answer 61

Benzocaine

Question 62

Ester or amide: Cocaine

Answer 62

Ester

Question 63

Which anesthetic can reduce bleeding and is sometimes used for dental procedures?

Answer 63

Cocaine 🦷

Question 64

What is the major MOA of cocaine?

Answer 64

Increasing dopamine in the CNS and periphery | The anesthetic effects are secondary

Question 65

What are the adverse effects of cocaine?

Answer 65

CNS Cardiovascular

Question 66

Ester or amide: Lidocaine

Answer 66

Amide

Question 67

Which drug should NOT be used for spinal blocks since it can cause transient neurological symptoms

Answer 67

Lidocaine

Question 68

Ester or amide: Prilocaine

Answer 68

Amide

Question 69

Which anesthetic has the highest clearance rate of all the amides, which makes it very safe?

Answer 69

Prilocaine

Question 70

What iOS the biggest risk of prilocaine?

Answer 70

Methemoglobinemia due to its metabolites

Question 71

Ester or amide: Bupivacaine

Answer 71

Amide

Question 72

Which anesthetic has the highest risk of cardiotoxicity?

Answer 72

Bupivacaine 💔

Question 73

For some reason, i decide to get pregnant. When I’m in the delivery room, screaming for an epidural, which local anesthetic will the CRNA inject into my epidural space?

Answer 73

Bupivacaine 🤰🏼

Question 74

Bupivacaine is more potent as a (sensory/motor) block

Answer 74

Sensory (Decreases pain, not motor function. Which i thought was the point of all of these, but he made a special mention of this and then said it again in the review, so i guess you should know it)

Question 75

Ester or amide: Ropivacaine

Answer 75

Amide

Question 76

Which LA is the S-enantiomer of Bupivacaine?

Answer 76

Ropivacaine 🤚🖐

Question 77

Which has more cardiac toxicity: bupivacaine or its mirror image twin, ropivacine

Answer 77

Bupivacaine

Question 78

At clinical doses, what effect does Ropivacaine have on the vasculature?

Answer 78

Vaso-constricting!!! | Most others dilate

Question 79

Ester or amide: Mepivacaine (Carbocaine)

Answer 79

Amide

Question 80

Ester or amide: Etidocaine (Duranest)

Answer 80

Amide

Question 81

Which anesthetic has the tendency to cause an inverse differential block, causing motor block before or without a sensory block?

Answer 81

Etidocaine (Duranest)

Question 82

Ester or amide: Articaine (Septocaine)

Answer 82

Amide WITH an ester group!!! | =two routes of metabolism

Question 83

Which anesthetic has two routes of metabolism since it is an amide as well as an ester?

Answer 83

Articaine (septocaine)

Question 84

Why do we care if articaine (septocaine) has two routes of metabolism?

Answer 84

It decreases the half life and thus, potential for systemic toxicity. Which means when your dentist is drilling away at your teeth and all of a sudden you start feeling pain again, he can inject more of it later in the procedure and not have to worry about systemic toxicity from giving you so much freaking anesthetic, you baby

Question 85

Ester or amide: Dibucaine (Nupercainal)

Answer 85

Amide-type

Question 86

Which anesthetic is used to measure how much butyrylcholinesterase activity someone has, and can identify people with mutations/deficiencies in this enzyme?

Answer 86

Dibucaine (Nupercainal)

Question 87

What is the “Dibucaine number test?’

Answer 87

Its the test to measure how much butyrylcholinesterase activity you have to see if you can metabolize ester anesthetics

Question 88

Which muscle relaxers (spasmolytics) are centrally-acting?

Answer 88

Baclofen (Lioresal) Cyclobenzaprine (Flexeril) Diazepam (Valium) Tizanidine (Zanaflex) Carisoprodol (Soma)

Question 89

Which muslce relaxers (spasmolytics) are direct acting?

Answer 89

Dantrolene Botox

Question 90

Which receptor is targeted by Diazepam (Valium)?

Answer 90

GABA “A” receptor Causes GABA-mediated inhibition in the spinal cord

Question 91

Which receptor is targeted by Baclofen (Lioresal)

Answer 91

GABA “B”

Question 92

What do you need to know about GABA B receptors?

Answer 92

They are Ga-i protein coupled and metabotropic Dont know what this means but he said it in the review

Question 93

What is the MOA of Tizanidine (Zanaflex)?

Answer 93

a2 receptor agonist - decreases glutamate

Question 94

What is the MOA of Baclofen (Lioresal)?

Answer 94

It is a GABA B agonist, which hyperpolarizes the membranes and inhibits Calcium influx. This decreases transmitter release

Question 95

What are the 2 effects of Tizanidine (Zanaflex)?

Answer 95

1. ) Pre and post-synaptic inhibition of spinal cord activity to decrease muscle spasticity 2. ) Inhibits pain transmission in dorsal horn

Question 96

What is the MOA of Dantrolene (Dantrium)?

Answer 96

Prevents the excitation-contraction coupling of actin and myosin in skeletal muscle fibers

Question 97

What muscle relaxer is used to treat neuroleptic malignant syndrome?

Answer 97

Dantrolene (Dantrium)

Question 98

Centrally or Direct acting: Dantrolene (Dantrium)

Answer 98

Direct

Question 99

What is the MOA of Botox?

Answer 99

Inhibits ACh release from the nerve at neuromuscular junction

Question 100

How is Botox administered?

Answer 100

Injected locally to control muscle spasms

Question 101

The pharmacokinetic property that regulates the duration of action of anesthetics is:

Answer 101

Time at site of action

Question 102

Which is a major difference between ester and amide anesthetics: A. Allergic reactions are common with amides B. Esters are metabolized by CYP450s and amides are not C. Esters have less toxicity D. Amides have different mode of action E. Esters have a shorter duration of action

Answer 102

E. Esters have a shorter duration of action

Question 103

The pharmacokinetic property that regulates the adverse effects and toxicity is:

Answer 103

Half life

Question 104

What is an advantage that Ropivacaine has over Bupivacaine ? A. Absorbed easier B. Longer duration of action C. Less potential for adverse effects D. It is more potent E. Metabolized in plasma

Answer 104

C. Less potential for adverse effects (It is less lipid soluble and cleared more rapidly, so this leads to lower potential for adverse effects, including less cardiac toxicity than Bupivacaine)

Question 105

Metabolites of prilocaine can cause this condition:

Answer 105

Methemoglobinemia

Question 106

What is the prototype amide anesthetic?

Answer 106

Lidocaine

Question 107

Which LA’s are Esters?

Answer 107

Procaine Tetracaine Benzocaine Cocaine

Question 108

Which LAs are amides?

Answer 108

Lidocaine Prilocaine Bupivacaine Mepivacaine Ropivacaine Etidocaine Articaine Dibucaine