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Pharm 2 > **in progress** Lecture 17 (Exam 4 Local Anesthetics Part II) > Flashcards

**in progress** Lecture 17 (Exam 4 Local Anesthetics Part II) Flashcards

1
Q

What is the average pKa of local anesthetics?

A

8

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2
Q

What is the function of the Alkalinization of LA Solutions?

What are the benefits of alkalinization?

A

Alkalinization increases the percentage of lipid-soluble or non-ionized forms.

Benefits:
* Faster onset of action
* Peripheral and epidural blocks by 3 to 5 mins.
* Enhances the depth
* Increase the spread (i.e., epidural)

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3
Q

If Drug V (weak base) has a pKa of 9.1, will the drug be more ionized or nonionized at physiological pH?

A

pKa - pH
9.1 - 7.4 = +1.7

Drug V will be more ionized at physiological pH.

Weak Bases, pKa before pH
Weak Acids, pKa afterpH

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4
Q

If the pKa of LA (a weak base) is at 4.5, will the drug be more ionized or nonionized at physiological pH?

A

pKa - pH
4.5 - 7.4 = -2.9

LA will be more non-ionized at physiological pH.

Weak Bases, pKa before pH
Weak Acids, pKa afterpH

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5
Q

LA1’s pKa is 9.2, and LA2’s pKa is 7.5. Which of the following are correct when placed in physiological pH? Select 2 answers.

A. LA2 has more non-ionized components
B. LA1 has more ionized components
C. LA2 has more ionized components
D. LA1 has more non-ionized components

A

B and C

LA1
9.2 - 7.4 = +1.8 (ionized)

LA2
7.5 - 7.4 = +0.1 (ionized)

Weak Bases, pKa before pH
Weak Acids, pKa afterpH

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6
Q

What adjuvant medication prolongs the duration of local anesthetics?

A
  • Dexmedetomidine
  • Magnesium
  • Clonidine
  • Ketamine
  • Dexamethasone
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7
Q

What will be the results of combining LA Chloroprocaine & Bupivacaine?

A
  • Produce a rapid onset
  • Tachyphylaxis (bupivacaine)
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8
Q

What is added to 30 mL of LA to alkalinize the drug?

A

1 mL of 8.4% Sodium Bicarbonate

This will increase the non-ionized form of LA.
Make sure the mixture does not contain any precipitate.

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9
Q

The toxic effects of combining LA are _______

A

Additive. (1+1 =2)

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10
Q

Compare the onset of action between chloroprocaine and bupivacaine.

A

Chloroprocaine: Rapid
Bupivacaine: Slow

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11
Q

What vasoconstrictors are available to use with LA?

A

Epinephrine
Phenylephrine

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12
Q

Why is it important to use vasoconstrictors with LA?

A

The duration of action of a LA is proportional to the time the drug is in contact with nerve fibers. For this reason, epinephrine may be added to LA solutions to produce vasoconstriction, which limits systemic absorption and maintains the drug concentration in the vicinity of the nerve fibers to be anesthetized.

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13
Q

What are the results of using vasoconstrictors with LA?

A
  • Produce vasoconstriction
  • Increased neuronal uptake of LA
  • α-adrenergic effects may have some degree of analgesia
  • No effect on the onset rate of LA
  • Enhanced cardiac irritability with inhaled anesthetics
  • Systemic absorption → HTN (tachycardia)
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14
Q

What is epinephrine 1:200,000 mean?

Convert that to mcg/mL.

A

1:200,000 means 1 gram of epinephrine is dissolved in 200,000 mL of solvent.

  • 1g/200,000 mL
  • 1000mg/200,000 mL
  • 1 mg/200 mL
  • 1000 mcg/200 mL
  • 10 mcg/2 mL
  • 5 mcg/mL
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15
Q

Compute 1:500,000 to mcg/mL

A

2 mcg/mL

  • 1 g/500,000 mL
  • 1000 mg/500,000 mL
  • 1 mg /500 mL
  • 1000 mcg/500 mL
  • 10 mcg/5 mL
  • 2 mcg/mL

Shortcut: 1,000,000 divided by the solvent number. 1 million/500,000 = 2 mcg/mL

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16
Q

How much epinephrine or phenylephrine is given with bupivacaine or lidocaine for a subarachnoid block (SAB)?

A
  • 0.2 mg Epi
  • 0.2 mg Phenylephrine
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17
Q

Compute 1:500,000 Epi to mcg/mL

A

1,000,000/ 500,000=2

2 mcg/mL

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18
Q

Compute 1:10,000 Epi to mcg/mL

A

1,000,000/ 10,000 = 100

100 mcg/mL

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19
Q

Compute 1:1000 Epi to mcg/mL

A

1,000,000/ 1000 = 1000

1000 mcg/mL

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20
Q

0.25%

A

2.5 mg/mL

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21
Q

0.5%

A

5 mg/mL

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22
Q

1%

A

10 mg/mL

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23
Q

2%

A

20 mg/mL

2% lidocaine is the most common concentration used in the OR

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24
Q

4%

A

40 mg/mL

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25
Your surgeon injected 20 mLs of Bupivacaine 0.25% with 1:200,000 of Epi. What are the total mgs for Bupivacaine and the total mcgs for Epinephrine?
Bupivacaine: 0.25% = 2.5 mgs/mL 2.5 mgs x 20 mLs = 50 mgs total Epinephrine: 1:200,000 = 5 mcg/mL 5 mcg x 20 mLs = 100 mcg total
26
Lidocaine Recommended Max Single Dose: Lidocaine Recommended Max Single Dose with/Epi Lidocaine Recommended Max Single Dose for Spinal
300 mg 500 mg w/ Epi 100 mg
27
Mepivacaine Recommended Max Single Dose Mepivacaine Recommended Max Single Dose with/Epi Mepivacaine Recommended Max Single Dose for Spinal
400 mg 500 mg w/ Epi 100 mg
28
Prilocaine Recommended Max Single Dose
600 mg
29
Bupivacaine Recommended Max Single Dose Bupivacaine Recommended Max Single Dose with/Epi Bupivacaine Recommended Max Single Dose for Spinal
175 mg 225 mg w/ Epi 20 mg
30
Clinical Scenario Question 112.5 mg of Bupivacaine with Epi and 250 mg of Lidocaine with Epi were given during surgery. What are the percentages of each LA based on the recommended max single dose in mg?
Max single dose of Bupivacaine with Epi: 225 mg 112.5/225 = 50% Max single dose of Lidocaine with Epi: 500 mg 250/500 = 50%
31
Where are topical anesthetics applicable?
Applicable on the mucous membranes of the nose, mouth, tracheobronchial tree, esophagus, or GU tract.
32
Which anesthetic has localized vasoconstriction?
Cocaine
33
Which anesthetic is great with surface anesthesia?
Lidocaine
34
Lidocaine nhalation does not alter airway resistance, but ______
vasodilation
35
What LA care not effective for topical anesthetic?
Procaine and Chloroprocaine
36
Rank topical anesthetic base on strength
Cocaine (4% to 10%) > Tetracaine (1% to 2%), Lidocaine (2% to 4%)
37
What is an LTA?
(lidocaine tracheal anesthesia) (localized tracheal anesthesia) (laryngeal tracheal anesthesia) Slide 23
38
Eutectic Mixture of LA (EMLA) contains what LA? Dose: Onset:
Lidocaine 2.5% and Prilocaine 2.5% = 5% LA Dose: 1 to 2 gms/ 10 cm2 area Onset: 45 mins
39
When do you have to wait two hours for EMLA?
2 hours Skin grafting
40
EMLA 10 mins
Cautery of genital warts Venipuncture, lumbar puncture Arterial cannulation (Nitroglycerine) Myringotomy
41
EMLA considerations
EMLA Caution with methemoglobinemia Not recommended for skin wounds C/I with amide allergies
42
Other Topical Anesthesia Preparations besides EMLA
Other Preparations: Amethocaine (EMLA-like) Tetracaine 4% Gel Lidocaine 7% Tetracaine 7%
43
Local Infiltration
44
Local Infiltration
45
Local Infiltration
46
How is Peripheral Nerve Block achieved? MOA?
Achieved by LA injection into tissues surrounding individual peripheral nerves or nerve plexuses. MOA: diffusion from outer mantle to central core of nerve along a concentration gradient. *** Smallest sensory and ANS fibers first, then larger motor and proprioceptive axons.***
47
Signs and Sx of Peripheral Nerve Block?
Proximal affected first and then distal.
48
When the peripheral nerve block is wearing off, what comes back first? Proximal or Distal?
Proximal comes back first & then distal.
49
Peripheral Nerve Block onset of action is dependent on _________. Lidocaine OOA: Bupivacaine OOA:
LA pK 3 mins 15 mins
50
Peripheral Nerve Block Duration depends on _____ of local anesthetic.
dose
51
Continuous Infusion Blocks
* Improved pain control, less nausea, & greater satisfaction * Additives are used
52
Examples of Peripheral Nerve Blocks
* Interscalene * Axillary * Femoral * Sciatic
53
Sciatic Nerve Block...
54
What is a Region Bier Block?
Bier Block IV injection of LA into an extremity isolated from the rest of the systemic circulation with a tourniquet. Sensation and muscle tone dependent on tourniquet
55
What LA is commonly used in Bier Block?
Lidocaine
56
Bier Block Steps
IV start Exsanguination Double cuff LA injection IV D/C
57
For a segmental block in Neuraxial Anesthesia, what fibers will be affected first.
Myelinated Preganglionic B fibers (fastest) (SNS) * This will affect BP (↓) an HR(↓)
58
Second fibers blocked?
59
What fibers will be blocked last.
60
Sequence of Blockade
1. SNS 2. Sensory 3. Motor
61
Clinical Scenario: Neuraxial blockade A. B. C. D.
D. Leg Movement
62
How is a Spinal Anesthesia Block (SAB) produced?
Produced by direct injection of LA into subarachnoid
63
Spinal Anesthesia Block (SAB), what is used for confirmation?
CSF
64
What is the principal site of action for SAB?
Preganglionic fiber
65
What SAB, the _______ effect is on the same level of denervation.
sensory
66
_____ is 2 spinal segments cephalad of sensory ______ is 2 spinal segments below sensory
SNS Motor
67
What dermatoses correspond with our cardiac accelerator?
T1 to T4
68
Clinical Scenario Slide: If the assessed sensory level after SAV is T6 ( Top of Xiphoid Process)....
69
Most common LA used in SAB
Most common: Tetracaine, Lidocaine, Bupivacaine, Ropivacaine, and Levobupivacaine
70
The dosage of SAB block is according to what three factors?
* Height of patient (volume of subarachnoid space) * Segmental level of anesthesia desired * Duration of anesthesia desired
71
For SAB, _____ is more important than _______ of drug (%) or the volume (mLs) of the solution injection.
Dose; Concentration
72
5 ft = _____mL of 0.75% Bupivacaine + ______ mL for every inch above…. 2 cc total ( 1½ hours to 2 hours)
1 mL 0.1 mL
73
For SAB, the _________ of LA is important in determining the spread of the drug.
specific gravity
74
Hyperbaric (LA sp. gr. > CSF) with _______ is additive Hypobaric with ________ as additive
glucose distilled water
75
Right-sided hip arthroplasty example
76
Hypobaric example
77
The most common LA used in Epidural Anesthesia
Lidocaine
78
What vasoconstrictors are available to use with LA?
Epinephrine Phenylephrine

Pharm 2 (8 decks)

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