Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

AU15 - Pharmacology Test 2 > Local Anesthetics > Flashcards

Local Anesthetics Flashcards

1
Q

Rules of the Henderson-Hasselbalch equation (pertaining to this class)

A

Acid form has a proton that is lacking form the basic form

Either the basic form is negatively charged or the acid form is positively charged

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Review how to calculate how much of the basic form there is…

A

Good job!

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are the 3 structural components of a local anesthetic?

A

Amine group
Ester or amide linkage
Aromatic group

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is the difference in ester or amide linkage?

A

Local anesthetics with an ester linkage are hydrolyzed by pseudocholinesterases and have a short plasma half life
Anesthetics with amide linkage are metabolized in the liver and have a longer half life
Esters are more allergenic
Amides have an ‘i’ somewhere in their name prior to “caine”
amides are favored in dentistry

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the significance of the amine group of local anesthetics?

A

It will be a 1’, 2’, or 3’ amine (2’ and 3’ are favored in dentistry)
Uncharged form of the amine will help cross cell membranes where they can produce a block
Once inside the cell, the charged form will bind better to the Na channel to block it
So both acid and basic forms are important

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

T/F - S and R forms of chiral drugs act the same

A

False - they may have different or similar pharmacokinetic and/or pharmacodynamic properties
They act as different molecules with different receptors and different actions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the molecular mechanism of local anesthetics?

A

They cross the axon membrane and block Na channels in their open and inactive states

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Why are both the ionized and nonionized forms of a local anesthetic important?

A

The form without the proton crosses the membrane

The form with the proton blocks the Na channel

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are the major structures of a peripheral nerve?

A

Fascicle

Connective tissue coverings

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Fascicle

A

Organized bundle of nerve fibers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What are the connective tissue coverings of a peripheral nerve?

A

Epineurium
Perineurium
Endoneurium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Epineurium

A

Outermost layer

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Perineurium

A

Surrounds fascicles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Endoneurium

A

Surrounds individual nerve fibers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What type of nerve fiber is the most important to local anesthetics?

A

D fibers
Deal with pain and temperature
Heavily myelinated

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Which nerves do local anesthetics inactivate faster?

A

Nerves that fire APs more frequently

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Are A, B, or C fibers more readily disrupted by local anesthetics?

A

B and C are more readily disrupted than A

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is the relationship between neuron diameter and sensitivity to local anesthetics?

A

Narrower fibers are more sensitive to local anesthetic than wide

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is the “first on, last off” principle?

A

The faster a fiber is blocked, the longer it takes to recover

20
Q

Would etidocaine or bupivacaine be favored for an epidural?

A

Bupivacaine, because it produces sensory anesthesia at 1/3 the concentration required for motor blockage, but etidocaine shows no selectivity
It provides anesthetic, but maintains uterine muscle contractility

21
Q

Why is inflammed tissue more difficult to anesthetize?

A

Products released by cells in inflammed tissue lowers pH, making it more difficult to get sufficient levels of anesthetic in the cell

22
Q

Why must we balance lipophilicity and hydrophilicity with local anesthetics?

A

Anesthetic must be sufficiently hydrophilic to diffuse to its site of action
But once at the site, the more lipid-soluble local anesthetic have a longer duration of action

23
Q

Why is the pKa important for local anesthetics?

A

The pKa can’t stray too far from the physiological pH, because we need ionized and unionized forms to bind the channel and enter the cell, respectively

24
Q

What happens to the pH is we add epinephrine to a local anesthetic?

A

It is lowered to 4-5 to stabilize the epinephrine
The buffering capacity at the injection site should neutralize this
Some might add NaHCO3 to add free base, but this risks precipitating the local anesthetic

25
Q

What pharmacology/toxicology effects can local anesthetics have on the CNS?

A

Local anesthetics readily pass from the periphery to the CNS

CNS is very sensitive to local anesthetics - bloodstream concentrations that don’t effect periphery can still effect CNS

26
Q

What pharmacology/toxicology effects can local anesthetics have on the cardiovascular system?

A

Direct effects

  • block Na channels
  • block Ca channels at very high concentrations
  • depress pacemaker activity, excitability, and conduction

Indirect effects
-inhibit sympathetic responses: depress contractility and produce hypotension

27
Q

What local anesthetic can be especially cardiotoxic?

A

Bupivicaine - binds tighter to Na channels and leaves slower

28
Q

Which type of local anesthetic are more significantly related to allergic reactions?

A

Esters (but amides are used in dentistry so who cares)

29
Q

What pharmacology/toxicology effects can local anesthetics have on vasoconstriction?

A

Epinephrine can cause vasoconstriciton

30
Q

What is the benefit of adding epinephrine to local anesthetics?

A

Better success rate and intensity of the anesthetic
Toxicity of anesthetic is reduced
Less blood loss

31
Q

What are problems of adding epinephrine to local anesthetics?

A

Usually no problems unless there’s excess dosing or inadvertent intravascular injection, which lead to cardiovascular side effects

32
Q

What is the limit for epinephrine injection in one session?

A

200 ug for a normal patient

40 ug for a compromised patient

33
Q

T/F - all local anesthetic get absorbed

A

True

34
Q

Why is it important to supply a vasoconstrictor (epinephrine) with lidocaine and procaine?

A

They produce potent vasodilation to be more readily absorbed

35
Q

How do local anesthetics get distributed?

A

They bind to plasma proteins, and unbound drugs are free to diffuse into various tissues, including the CNS and placenta

36
Q

Why is absorption in the liver of local anesthetic important?

A

Absorption (and metabolism) by the liver are important to keep systemic concentration of amide local anesthetics low

37
Q

What is the plasma half life of ester local anesthetics?

A

less than a minute, because they are hydrolyzed by pseudocholinesterases in the plasma and tissues

38
Q

What is the half life of amide local anesthetics?

A

1.5-3.5 hours - hydrolyzed in the liver

exceptions are prilocaine and articaine which are metabolized quickly

39
Q

What are the guiding principles of administering local anesthetics to do so safely?

A

1) administer the smallest dose that’s effective
2) use proper injection technique
3) use a vasoconstrictor-containing solution unless contraindicated

40
Q

What do you do if patient has convulsions due to local anesthetic administration?

A

Treat with benzodiazepine, barbituate, or succinylcholine

41
Q

What do you do if a patient is in respiratory distress due to local anesthetic administration?

A

Ventilaiton and oxygen treatment

42
Q

What do you do if a patient has hypotension due to local anesthetic administration?

A

Treat with sympathomimetic agents (epinephrine)

43
Q

What do you do if patient has a dermatological allergic reaction to local anesthetics?

A

Treat with antihistamines

44
Q

What do you do if patient goes into anaphylaxis do to local anesthetic allergic reaciton?

A

Epinephrine

45
Q

What category of drug is lidocaine and prilocaine?

A

Category B - safe to use during pregnancy

46
Q

What category of drug is articaine, mepivacaine, and bupivacaine?

A

Category C - weight the risks before use during pregnancy

47
Q

Why are local anesthetics thought to be safe?

A

Low doses used in dentistry (1/10 dose to what is used in epidural)
Low fatalities
Adverse effects are around 3% - and the “symptoms might reflet anxiety

AU15 - Pharmacology Test 2 (10 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions