Pain and Anxiety Week 2 Flashcards
(195 cards)
1
Q
New FDA law requires LA carpule labeling to say?
A
1.7 mL
(each carpule contains 1.8 mL but law requires labeling to say 1.7 mL if manufacturer cannot guarantee all carps contain exactly 1.8 mL)
2
Q
Which LA is no longer available in the US?
A
2% Lidocaine Plain
3
Q
LAs are manufactured in _________ ________ cartridges/carpules
A
single use
4
Q
What are the 4 possible % solutions LAs can be produced as?
A
0.5%
2%
3%
4%
5
Q
What 5 things can be included in LA carpules?
A
LA drug
Sodium hydroxide (buffering agent)
Sodium chloride (buffering agent)
Vasoconstrictor (epi or levonordefrin)
Vasoconstrictor preservative (sodium bisulfite)
6
Q
Name 2 buffering agents that can be in the carpule
A
sodium hydroxide and sodium chloride
7
Q
The vasoconstrictor present in the carpule
A
epi or levonordefrin
8
Q
This vasoconstrictor preservative helps decrease the solution pH (more acidic) to delay the onset of the LA
A
Sodium bisulfite
9
Q
If a pt reported that they had an allergic rxn to a LA before 1984, then what were they probably allergic to?
A
Parabens
10
Q
Prior to 1984, LA solutions without epi added _________________ as a preservative, which increased ________ _______, so it is no longer added to LAs
A
methylparaben; allergic rxns
11
Q
What are the 2 ways LAs cause reversible local anesthesia?
A
preventing generation and conduction of impulses
12
Q
LAs provide a ________ _______ between source of impulse and brain (impulse never reaches the brain)
A
chemical block
13
Q
LAs are known as “___________ ___________ drugs,” meaning they decrease the rate of depolarization
A
membrane-stabilizing
14
Q
What do LAs inhibit the influx of during depolarization?
A
Na+
15
Q
LAs bind to Na+ channels inside/outside the cell
A
LAs bind to Na+ channels INSIDE the cell
16
Q
What do LAs provide to allow easier binding to Na+ channels that are firing (NOT resting)?
A
State-dependent blockade
17
Q
Small diameter nerves are……
A
More sensitive to LAs
18
Q
Large diameter nerves require…..
A
More volume of LAs
19
Q
Name the 5 actions of LAs
A
- Diffuse through neuron cell membrane
- Bind Na+ channels (inside cell membrane)
- Prevent Na+ channels from opening
- Prevents conduction of nerve impulse
- Prevents neuron from reaching firing potential
20
Q
2 major routes of LA delivery
A
- Topical (applied on mucosa, higher concentration needed to penetrate mucosa, higher toxicity)
- Submucosal injection (more effective, less concentrations needed)
21
Q
2 groups of LAs
A
Esters
Amides
22
Q
Esters are metabolized in the ______ via _____________ while amides are metabolized in the _________
A
blood (plasma); psuedocholinesterase; liver
23
Q
ALL injectables LAs are…
A
Amides
24
Q
Topical LAs can be…
A
Esters or amides
25
Which group of LA has the most allergic reactions?
Esters
26
Amides have a low _______________ with esters
cross-hypersensitivity
27
Describe the chemical structure of LAs
1) lipophilic aromatic ring
2) intermediate linkage
3) hydrophilic terminal amine
28
Characteristics of the lipophilic aromatic ring of LA
Base = inactive form
Determines potency
Penetrates membrane, but CANNOT bind receptors unless it picks up H+
29
What does the intermediate linkage of LA determine?
If the LA is ester or amide
30
Characteristics of the hydrophilic terminal amine of LA
Dissociates becoming tertiary amine -> enters nerve -> gains H+ -> ionized -> binds to receptor sites -> ACTIVE form
CANNOT enter neurons until it loses H+, must pick it up again inside
31
Once the LA has gained a ________ ion, it's now in it's ___________ form
H+; active
32
Cation form of LA
Active
Only binds to sites within nerve
33
Anionic form of LA
Inactive
Does NOT bind to receptor sites
34
Physiological effects of drug on the body
Pharmacodynamics
35
L.A. molecules in the cartridge include anions and cations. How do they differ with their onset?
More anions: low pKa, more base, fast diffusion, rapid onset
More cations: high pKa, less base, slow diffusion, slow onset
36
All LAs are __________ solutions before injection, meaning there are more __________ than ________ in the cartridge
acidic; cations; anions
37
Higher pKa means what?
Less base
Slower onset of action
38
Lower pKa means what?
More base
Rapid onset of action
39
Infected tissues are __________
acidic
40
What happens when you inject LA into infected, acidic tissue?
Less molecules cross the membrane = INADEQUATE ANESTHESIA
41
What happens to the H+ in infected, acidic tissue?
RNH+ molecules cannot dissociate H+, so the active form CANNOT enter the cell membrane
42
What does RNH+ refer to?
Cation (acid) = ACTIVE form that CANNOT cross membrane
43
What does RN refer to?
Anion (base) = INACTIVE, lipid soluble form that CAN cross the membrane
44
L.A. must penetrate _______mm of myelinated nerve length (3-4 nodes of Ranvier) to block a nerve impulse
8-10mm
45
↑___________ of L.A. is required for large nerves (inferior alveolar n.)
volume
46
Increased concentration of LA means...
Increased diffusion through membrane
Rapid onset
47
Low pKa of LA means...
Increased RN molecules (anions)
Increased base
Rapid onset
48
High lipid solubility of LA means...
Increased potency
Decreased dose needed (enhances diffusion of drug through nerve)
49
Increased protein binding of molecules in LA means...
Increased duration
(binds more strongly to receptor, prolonging anesthetic presence at site of action)
50
Increased vasodilation of LA means...
Decreased potency + Decreased duration
Must increase dose!
(vasodilation = increased blood flow = increased removal of LA molecules from site)
51
Describe the onset if there is a high concentration of the LA and it has a low pKa
Rapid onset
52
What happens to the dosage if the lipid solubility decreases?
Increase the dose
(to enhance diffusion of drug through the nerve)
53
What happens to the duration of the LA if there is increased protein binding?
Increased duration
54
T/F: LAs are vasodilators
True
55
Period from LA deposit to blocked impulse conduction
Onset of action
56
What is the primary factor for determining the onset of action of a LA?
pKa!!
low pKa = rapid onset
high pKa = slow onset
57
What does pKa determine the amount of?
Ionized molecules in solution
58
What is the secondary factor for determining the onset of action of a LA?
Site!!
small diameter nerves = rapid onset
59
Diffusion of molecules across membrane
Induction of LAs
60
What is the primary factor for determining the induction of a LA?
Initial concentration of LA
inc conc = inc diffusion = rapid onset
dec conc = dec diffusion = slow onset
61
Name some areas in the body where the anesthetic loses concentration from
Tissue fluid
Capillaries
Lymphatics
Anatomic barriers (bone)
62
Reversal of LA action
Recovery from LA block
63
What is the primary factor for determining the duration of action and speed of nerve recovery?
Degree of protein binding
(different for each LA, depends on chemicals)
64
T/F: Recovery is a slower process than induction
True
65
If you try to reinject LA and the nerve fibers are only partially recovered (pt still numb), what volume of LA is effective and what is the speed of onset of action?
Small volume is effective
Rapid onset of action
66
If you try to reinject LA and the nerve fibers are fully recovered (no numbness), what can occur?
Tachyphylaxis = tolerance to LA = LA is ineffective!
67
Potency
Duration of LA
68
What are the 3 factors that affect the duration/potency of LA?
Protein binding
Vascularity of injection site
Vasoconstrictor in LA
69
Stronger protein binding means _________ duration and __________ potency
increased; increased
70
Increased vascularity of injection site means ___________ duration and ___________ potency
decreased; decreased
71
Presence of a vasoconstrictor in the LA means ___________ blood flow, ___________ duration, and ___________ potency
decreased; increased; increased
72
After absorption, where are LAs distributed?
Throughout body
73
Which organs have higher concentrations of LA?
Highly vascular organs
74
Name 5 examples of highly vascular organs that will have higher concentrations of LA
Brain
Heart
Lungs
Liver
Kidneys
75
What is toxicity directly related to?
Amount of LA accumulated in tissues
76
Increased absorption means there is an __________ risk of systemic ___________
increased; toxicity
77
Increased dose means there is ____________ absorption. All molecules diffused out of _______ channels into ____________
increased; Na+; bloodstream
78
Increased concentration means there is ____________ absorption
increased
79
Which route of administration will allow for increased absorption?
Topical
80
An intravascular injection will cause __________ absorption
increased
81
Increased vasoconstrictor in the LA will cause ____________ absorption
decreased
82
T/F: The presence of a vasoconstrictor increases absorption.
FALSE
it decreases bc you're constricting the blood vessel so less flows into bloodstream
83
All LAs are _______________
vasodilators!
84
Biotransformation refers to the ____________ of a drug
metabolism
85
How is biotransformation measured?
In half-life (time for 50% of drug to be removed)
86
Increased half life means ___________ risk for systemic toxicity
increased
(the drug is lingering around in tissue for much longer)
87
Name 3 ester LAs
1. Procaine
2. Tetracaine
3. Benzocaine
88
What is the route of administration for ester LAs?
Topical
89
What is the route of administration for amide LAs?
Injectable and topical
90
Which amide LAs are metabolized in the liver only, and therefore have an increased toxicity in liver disease?
Lidocaine
Mepivacaine
Bupivacaine
91
Which amide LA is metabolized in the liver AND lungs?
Prilocaine
92
Which amide LA is metabolized in plasma (90%) and liver (10%)?
Articaine
93
Which amide LA has the SHORTEST half life?
Articaine
94
What is the primary excretory organ for all LAs?
Kidneys
95
Where are a small amount of ester LAs excreted?
Unchanged in urine
96
Where are a greater % of amide LAs excreted?
Unchanged in urine
(small amount, even tho more than esters)
97
Why is there an increased risk of systemic toxicity of LAs in patients with severe renal disease?
Due to build up of drug when not cleared by kidneys
98
Although small amounts of both esters and amides L.A.s are excreted unchanged in urine, which is excreted in a greater percent this way?
Amides
99
At what point can LAs affect the CNS and CV system?
After they are absorbed into blood (before metabolized)
(↑blood levels = ↑toxicity)
100
Toxicity and adverse reactions of LAs are directly related to what? (9)
1) Nature of specific L.A. (vasodilation)
2) Concentration of drug
3) Route of administration
4) Dose administered
5) Rate of injection
6) Vascularity of site
7) Age of patient
8) Weight of patient
9) Health of patient
101
Order of selection of LAs (5)
1) duration of pain control needed
2) need for post op pain control
3) patient's health assessment and current meds
4) allergic to the LA or sodium bisulfite
5) need for hemostasis
102
What is the highest concentration of epinephrine?
1:50,000
103
What is the lowest concentration of epinephrine?
1:200,000
104
If a pt is allergic to wine, dried fruit, or dried potatoes, then we assume they have a ___________ allergy
bisulfite
105
T/F: Most LAs are short-acting.
FALSE!
Most are intermediate-acting (60 mins of pulpal anesthesia)
106
Which LA is most commonly used in dentistry for nerve blocks?
Lidocaine
107
Which LA is good for hemostasis if 1:50,000 epi?
Lidocaine
108
Which LA is NOT available in US without epi?
Lidocaine
109
What is the duration of Lidocaine?
60 mins
110
Lidocaine brand name?
Xylocaine
111
Which LA is an effective topical and is the only amide topical?
Lidocaine
112
What is the onset of action of Lidocaine?
2-3 mins
113
Where is Lidocaine metabolized? What is the 1/2 life?
Liver (half life = 1.6 hrs)
114
What is the pregnancy category for Lidocaine?
pregnancy = category B; lactation safe
115
Which LA is a good choice if vasoconstrictor is contraindicated?
Mepivacaine
116
Which LA is NOT used for hemostasis since there is no epi?
Mepivacaine
117
Which LA is a WEAK vasodilator? (2)
Mepivacaine
Prilocaine
118
What is the duration of Mepivacaine (without epi and with levo)?
Duration w/o epi = 20-40 mins
Duration w/ levo = 60 mins
119
What is the onset of action of Mepivacaine?
1.5-2 mins
120
Where is Mepivacaine metabolized? What is the 1/2 life?
Liver (half life = 1.9 hrs)
121
What is the pregnancy category for Mepivcaine?
pregnancy = category C; lactation safe
122
Mepivacaine brand name?
Carbocaine
123
Which LA is the LEAST toxic in dentistry?
Prilocaine
124
Which LA is the BEST choice for pregnancy + CV pts?
Prilocaine
125
Which LA has a risk of methemoglobinemia?
Prilocaine
126
What patients should you be worried about for methemoglobinemia risk with Prilocaine?
COPD patients
127
Which LA has no anticonvulsant properties? (2)
Prilocaine
Articaine
128
Which LA is an effective topical when combined w/ lido?
Prilocaine
129
What is the duration of Prilocaine (with and without epi)?
Duration w/o epi = 40-60 mins
Duration w/ epi = 60-90 mins
130
What is the onset of action of Prilocaine?
2 mins
131
Where is Prilocaine metabolized? What is the 1/2 life?
Lungs + small amount in liver (half life = 1.6 hrs)
132
What is the pregnancy category for Prilocaine?
pregnancy = category B; lactation unknown safety
133
Prilocaine brand name?
Citnest
134
Which LA has a risk for IA nerve injury?
Articaine
134
Which LA is highly lipid soluble and has high diffusion thru bone?
Articaine
135
What is the pregnancy category for Articaine?
pregnancy = category C; lactation unknown safety
136
What is the duration of Articaine (with 1:100,000 epi and 1:200,000 epi?
Duration with 1:100,000 epi = 60-75 mins
Duration with 1:200,000 epi = 45-60 mins
137
What is the onset of action of Articaine?
1-3 mins
138
Where is Articaine metabolized? What is the 1/2 life?
Plasma (90%) + liver (half life = 45 mins)
139
Which LA is NOT an effective topical? (2)
Articaine
Bupivacaine
140
Which LA is highly lipid soluble and has high diffusion thru bone?
Articaine
141
Which LA is a good choice in CV + liver disease pts?
Articaine
142
Articaine brand name?
Septocaine
143
Which LA is MOST potent and toxic?
Bupivacaine
144
Which LA is the MOST potent vasodilator?
Bupivacaine
145
Which LA is good for long treatment?
Bupivcaine
146
Which LA has a HIGH toxicity risk?
Bupivcaine
147
T/F: You MUST give Bupivacaine with a vasoconstrictor (not available w/o epi)
True
148
What is the duration of Bupivacaine?
1.5-3 hours
149
What is the onset of action for Bupivacaine?
5-10 mins
150
Where is Bupivacaine metabolized? What is the 1/2 life?
Liver (half life = 2.7 hrs)
151
What is the pregnancy category for Bupivacaine?
pregnancy = category C; lactation unknown safety
152
Bupivacaine brand name?
Marcaine
153
The CNS is very sensitive to high levels of LA because they?
Readily cross BBB
154
Has this pt suffered from a moderate or high overdose of LAs?
Presents with:
increased HR, RR, BP, and also has muscle twitching with tremors
Moderate
155
Has this pt suffered from a moderate or high overdose of LAs?
Presents with:
decreased HR, RR, BP, they're convulsing and experiencing unconsciousness
High!
They are progressing to respiratory arrest due to CNS depression
156
Has this pt suffered from a moderate or high overdose of LAs?
Presents with:
increased HR, RR, BP, headache and feeling lethargic
Moderate!
They have initial cardiovascular stimulation
157
Has this pt suffered from a moderate or high overdose of LAs?
Presents with:
decreased HR, RR, BP, slurred speech, disoriented
High!
Progressing to cardiac arrest and cardiac depression
158
2 vasoconstrictors used in US
Epinephrine
Levonordefrin
159
4 functions of vasoconstrictors
1) constrict blood vessels @ site
2) increase duration of LA (6x longer)
3) provides hemostasis at injection site
4) decrease absorption rate of LA (and risk of toxicity)
160
Which vasoconstrictor affects alpha and beta receptors equally?
Epi
161
T/F: Levonordefrin affects the alpha receptors more.
True! 75% is alpha and 25% is beta
162
MRD for epi (healthy pt and CV disease)
Healthy MRD = 0.2 mg
CV disease = 0.04 mg
163
MRD for levonordefrin (healthy pt and CV disease)
Healthy MRD = 1.0 mg
CV disease = 0.2 mg
164
An overdose usually occurs via which route?
Intravascular injection
165
How fast due overdose symptoms appear? How long does it take for the body to clear the drug?
Symptoms appear within 60 seconds
Body clears within 5-10 mins
166
Symptoms of an overdose (6)
1) dysrhytmias
2) increased HR + BP
3) headache
4) hyperventilation
5) tremors
6) anxiety
167
What does an overdose lead to in patients with CV disease?
Cardiac arrest
168
Absolute contraindication for LA
Allergy
169
Relative contraindications of LA (6)
1) H2 receptor blocker
2) Beta blocker
3) CNS depressants
4) Pregnancy
5) Significant liver disease
6) Renal dysfunction
170
H2 receptor blockers decrease liver metabolism. What do you do when a pt is taking a H2 receptor blocker?
Decrease dosage of lidocaine
171
Beta blockers decrease amide metabolism. What do you do when a pt is taking a beta blocker?
Decrease dosage of all amides
172
CNS depressants can decrease metabolism. What do you do when a pt is taking a CNS depressant?
Decrease dosage of all amides
173
What do you do if your pt is pregnant?
Use prilocaine or lidocaine
174
Significant liver disease decreases amide metabolism. What do you do if your pt has significant liver disease?
Use articaine and/or decrease dosage of all amides
175
Renal dysfunction decreases excretion. What do you do if your pt has renal dysfunction?
Use LAs with caution
176
Absolute contraindications for vasocontrictors (5)
MI/coronary bypass surgery within 3-6 months
Uncontrolled hypertension, angina, arrythmias, hyperthyroidism
Sulfite allergy
Glaucoma
Cocaine/methamphetamine use
(basically anything heart related)
177
Relative contraindications of vasoconstrictors (4)
CVD pts
Tricyclic antidepressants
Nonselective beta blockers
Digitalis
178
What is cardiac protocol?
0.04 mg epi
0.2 mg levo
179
What do you do if your pt has CV disease?
Cardiac protocol
180
What do you do if your pt is taking tricyclic anti-depressants?
No levo
0.04 mg epi
181
What do you do if your pt is taking a nonselective beta blocker?
Cardiac protocol
182
What do you do if your pt is taking digitalis?
Consult physician
183
MRD stands for
Max recommended dose
184
What is MRD adjusted to accommodate?
Pts medical status
185
We use the lowest effective dose for...
Elderly
Children
Medically compromised
186
MRD is based on...
Maximum dose per appointment
Body weight
187
MRD is calculated as...
mg/lb or mg/kg
188
MRD and AMD of Lidocaine
MRD: 3.2 mg/lb
AMD: 500 mg
189
MRD and AMD of Mepivacaine
MRD: 3.0 mg/lb
AMD: 400 mg
190
MRD and AMD of Prilocaine
MRD: 4.0 mg/lb
AMD: 600 mg
191
MRD and AMD of Articaine
MRD: 3.2 mg/lb
AMD: none
192
MRD and AMD of Bupivacaine
MRD: none
AMD: 90 mg
193
How many mg of epi per carpule?
0.018 mg
194
In healthy pts, the ______________ is the limiting drug, but in cardiac pts the _______________ is the limiting drug
LA; vasoconstrictor
