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SUM'20 - Regional > Week 2 Weak Acids & Bases & pKa (Everything) > Flashcards

Week 2 Weak Acids & Bases & pKa (Everything) Flashcards

1
Q

LA are:

A

weak bases

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2
Q

Acid + Acid =

Base + Base =

A

non ionized

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3
Q

Acid + base =

A

ionized

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4
Q

Onset of LA

pH where 50% ionized and 50% non-ionized

A

pKa

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5
Q

Lipid solubility:

A

potency of LA

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6
Q

the more lipid soluble:

A

the more potent.

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7
Q

More lipid soluble impact on blood flow…

A

less likely for blood flow to carry it away

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8
Q

Protein binding=

A

duration of LA

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9
Q

Na+ channel are voltage gated and exist in

A

3 phases

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10
Q

The 3 phases of Na+ channel voltage gates:

A
  1. Resting or closed (M-gate closed)
  2. Activated or open (M-gate and H-gate are open)
  3. Inactivated (inactivated b/c H-gate is closed)
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11
Q

the LA interacts with the ______ to cause the effect

A

the H-gate

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12
Q

is a positive or negative charge of the LA required for the interaction with the H-gate to happen?

A

positive charge

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13
Q

what is the position of the M-gates and the H-gate when the na-channel is RESTING:

A

M-gates: closed

H-gate: open

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14
Q

what is the position of the M-gates and the H-gate when the na-channel is ACTIVATED:

A

M-gates: open

H-gate: open

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15
Q

what is the position of the M-gates and the H-gate when the na-channel is INACTIVATED:

A

M-gates: open

H-gate: closed

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16
Q

M-gates: open
H-gate: closed

the na-channel is:

A

inactivated

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17
Q

M-gates: open
H-gate: open

The na-channel is:

A

Activated

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18
Q

M-gates: closed
H-gate: open

The na-channel is:

A

Resting

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19
Q

Recover from the inactivated, refractory state requires closure of the _____ and opening of the _____.

A

closure of the m-gates

and opening of the h-gate.

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20
Q

LA bind to the (R) where?

A

within the channel

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21
Q

How do LA access the Receptor?

A

via the membrane phase OR from the cytoplasm

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22
Q

What form of the LA is needed to cross the phospholipid layer?

A

non-ionized

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23
Q

What for of the LA is needed to get inside the membrane in order to bind w/the H-gate?

A

ionized

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24
Q

Lipid soluble (non/ionized?)

A

non Ionized

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25
Q

Uncharged form ((non/ionized?)

A

non Ionized

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26
Q

Acid form (non/ionized?)

A

non Ionized

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27
Q

Generally hydrophobic (non/ionized?)

A

non Ionized

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28
Q

Readily penetrates BBB and Placenta (non/ionized?)

A

non Ionized

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29
Q

Water soluble (non/ionized?)

A

ionized

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30
Q

Charged Form (non/ionized?)

A

ionized

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31
Q

Conjugate base form (non/ionized?)

A

ionized

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32
Q

What delays onset?

A
  • drug with pKa farther from physiological pH (7.4). In this state more of the drug exists in the ionized form
  • environmental pH is acidic (<7.4);
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33
Q

examples of environments where pH is more acidic (<7.4):

A
  • wound infections

- ischemic areas

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34
Q

examples of environments where pH is more acidic (<7.4):

A
  • wound infections

- ischemic areas

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35
Q

Highly protein bound = what 2 things?

A
  1. harder to dissociate from Na channel

2. Longer DOA

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36
Q

DOA is associated with

A

Protein binding!

-higher protein binding = longer DOA

37
Q

The closer pKa is to physiologic pH the faster the

A

onset (relatively)

38
Q

to speed up onset:

A

pKa closer to physiologic pH

39
Q

pKa of Chloroprocaine:

40
Q

protein binding of Chloroprocaine:

A

none (Zero)

41
Q

pKa of Procaine:

42
Q

protein binding of Procaine:

43
Q

Drug that’s the Exception to the rule of faster onset

A

Chloroprocaine

44
Q

pKa of Lidocaine

45
Q

what can be used/added to the LA to either prolong the duration?

A

EPINEPHRINE

46
Q

What can be used/added to LA to gain quicker onset:

A

Bicarbonate

47
Q

What LA can precipitate when adding bicarbonate?

A

Bupivacaine

48
Q

**What is the dose of bicarbonate when mixed with Bupivacaine?

A

0.1 mEq per 20mL of Bupivacaine

49
Q

**What is the dose of bicarbonate when mixed with Lidocaine?

A

1 mEq of Bicarb per 10mL of Lidocaine

50
Q

***Epi will not increase DOA for

Why?

A

Bupivacaine
Etiocaine
Ropivacaine
-b/c they have a long duration naturally

51
Q

Which LA are short acting?

A

“Pro-C”
Procaine
Chloroprocaine

52
Q

Which LA are intermediate acting?

A

“LMP”
Lidocaine
Mepivacaine
Prilocaine

53
Q

Which LA are long acting?

A

“BET on a LONG shot”
Bupivacaine
Etidocaine
Tetracaine

54
Q

Prilocaine Short/Intermediate/Long acting LA?

55
Q

Lidocaine Short/Intermediate/Long acting LA?

A

Intermediate

56
Q

Bupivacaine Short/Intermediate/Long acting LA?

57
Q

Tetracaine Short/Intermediate/Long acting LA?

58
Q

Chloroprocaine Short/Intermediate/Long acting LA?

59
Q

Etidocaine Short/Intermediate/Long acting LA?

60
Q

Mepivacaine Short/Intermediate/Long acting LA?

A

intermediate

61
Q 
Drug X (a weak acid) has a pKa of 8.4 and is administered to a patient with a pH 7.4.  Which of the following is true regarding the drug?
A)  more than 50% ionized

B) more than 50% unionized

C) 50% unionized and 50% ionized

D) cannot be determined with information provided

A

B: more than 50% unionized

62
Q 
Drug X (a weak acid) has a pKa of 3.5 and is administered to a patient with a pH 7.4.  Which of the following is true regarding the drug?	
A)  more than 50% ionized

B) more than 50% unionized

C) 50% unionized and 50% ionized

D) cannot be determined with information provided

A

A: more than 50% ionized

63
Q 
Drug X (a weak acid) has a pKa of 3.5.  Which of the following is true regarding the drug?
A)  more than 50% ionized

B) more than 50% unionized

C) 50% unionized and 50% ionized

D) cannot be determined with information provided

A

D): cannot be determined with information provided

64
Q 
Drug X (a weak base) has a pKa of 3.5 and is administered to a patient with a pH 7.4.  Which of the following is true regarding the drug?
A)  more than 50% ionized

B) more than 50% unionized

C) 50% unionized and 50% ionized

D) cannot be determined with information provided

A

B) more than 50% unionized

65
Q 
Drug X (a weak base) has a pKa of 9.5 and is administered to a patient with a pH 7.4.  Which of the following is true regarding the drug?
A)  more than 50% ionized

B) more than 50% unionized

C) 50% unionized and 50% ionized

D) cannot be determined with information provided

A

A) more than 50% ionized

66
Q

Lidocaine has a pKa of 7.7 and is administered to a patient with a pH 7.7. Which of the following is true regarding the drug?
A) more than 50% ionized
B) more than 50% unionized
C) 50% unionized and 50% ionized
D) cannot be determined with information provided

A

C) 50% unionized and 50% ionized

67
Q

Weak bases become more ________ as pH increases

A

Non-ionized

68
Q

Should a weak acid be stored in a low or high pH solution? Why?

A

High pH solution (base)
Base + Acid = Ionized form
Should not precipitate
Mixing a weak acid with low pH solution would cause precipitation

69
Q

When a local anesthetic is injected into a physiologic pH environment, it will be:
A) less than 50% ionized
B) less than 50% unionized
C) 50% unionized and 50% ionized
D) Cannot be determined with information provided

A

B: less than 50% unionized (LA are weak bases)

70
Q

pKa range for LA

71
Q

how would an area of infection alter a LA block

A

Speed of onset is slower when LA is injected into an area of infection b/c it increases the extent of ionization which slows diffusion through the lipid bilayer

72
Q

what creates a faster onset for LAs

A

more unionized form = faster the onset

bc unionized is what crosses the membrane then it is activated to ionized form

73
Q

which LA are short acting

A

“Pro-C”

procaine & chloroprocaine

74
Q

which LA are intermediate acting

A

“L,M,Pri”

Lidocaine, Mepivicaine, Prilocaine

75
Q

which LA are long acting

A

“BET on a long shot”
bupivicaine, etidocaine & tetracaine

(not appropriate for outpatient surgery centers where we need to move the patients quickly. tetracaine last around 4 hours)

76
Q

LA with high a pKa are ____ at physiologic pH?

and require what fore effect?

A

Are highly ionized at physiologic pH

Has to have an open (activated) Na+ channels for effect

77
Q

which nerves have more frequent depolarization and what LA pKa are they susceptible to?

A

sensory & autonomic nerves

susceptible to high pKa LA

78
Q

which nerves have less frequent depolarization and what LA pKa are they susceptible to?

A

motor nerves

susceptible to lower pKa LA

79
Q

where is a sympathetic block compared to a sensory block

A

Sympathetic block is 2-6 dermatomes higher than sensory block

80
Q

where is a motor block compared to a sensory block

A

Motor block is 2 dermatomes lower than sensory block

81
Q

How does the LA progress in a blockade?

A
  • Autonomic, Temperature, Pain (ATP)
  • Touch, Pressure (TP)
  • Motor, Vibratory, Proprioception (MVP)
82
Q

what form of a drug can diffuse across the lipid bilayer into the axon in a conduction block?

A

Non-ionized

83
Q

what is the role of the ionized form of a LA in a conduction block

A

Ionized is needed to attach to the inside of the sodium channel and lock it in the inactivate state

84
Q

conduction blocks are _____ dependent?

A

frequency dependent

frequency of the Action Potential

85
Q

special consideration about myelinated axons. what must happen to achieve a block

A

2-3 nodes of Ranvier must be blocked to stop nerve conduction myelinated axons

86
Q

WEAK ACIDS COMBINE WITH POSITIVE CHARGED IONS SUCH AS:

A

Na+
Mg++
Ca++

87
Q

WEAK BASES COMBINE WITH NEGATIVELY CHARGED IONS SUCH AS:

A

CHLORIDE

SULFATE

88
Q

Example: are the following “drugs” weak acids or weak bases?

LIDOCAINE HYDROCHLORIDE:
SODIUM CETO:
MAGNESIUM TIBUCAINE:

A

LIDOCAINE HYDROCHLORIDE: weak base
SODIUM CETO: weak acid
MAGNESIUM TIBUCAINE: weak acid

89
Q

example question:
Drug X (a weak acid) has a pKa of 8.5 and is administered to a patient with a pH 7.4. Which of the following is true regarding the drug?
A) more than 50% ionized
B) more than 50% unionized
C) 50% unionized and 50% ionized
D) cannot be determined with information provided

A

B: more than 50% unionized

SUM'20 - Regional (17 decks)

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