ICU drugs Flashcards
1
Q
This is the time dependency of a drug; relationship between the dose of a drug and its plasma/tissue concentration;
A
pharmacokinectics
2
Q
What is pharmacokinectics?
A
relationship between dose of a drug and tissue concentration
3
Q
This is what the body does to the drug; absorption, distribution, metabolism, and elimination;
A
pharmacokinectics
4
Q
What is pharmacodynamics?
A
how plasma concentration of a drug exerts its effect on the body
5
Q
This is what the drug does to the body;
A
pharmacodynamics
6
Q
General anesthesia encompasses three parts:
A
unconsciousness (and amnesia)
analgesia
muscle relaxation
7
Q
These drugs commonly used for unconsciousness and amnesia:
A
propofol
ketamine
etomidate
benzos/barbs
8
Q
How does propofol work?
A
inhibits synaptic transmission thru its effects on GABA receptor
9
Q
This drug is used for unconsciousness and is an alkylated phenol that inhibits synaptic transmission thru its effects on GABA receptor:
A
propofol
10
Q
Why is propofol use attractive in smokers and asthmatics?
A
has bronchodilator properties
11
Q
Why do we use propofol cautiously in pts with hypovolemia and CAD?
A
causes hypovolemia
12
Q
Onset of action of propofol?
A
less than a minute
13
Q
Propofol is metabolized by?
A
liver
cleared 60% by liver, 40% by kidneys
14
Q
Half life of propofol?
A
biphasic
initially 40 minutes
terminal half life 4-7 hrs
15
Q
Adverse reactions of propofol?
A
local pain at injection site hypotension myoclonus QT prolongation (rare) green urine (rare)
16
Q
Propofol safe in pregnancy?
A
yes
crosses the placenta
17
Q
Propofol effects on the brain?
A
decrease in cerebral blood flow
decrease in intracranial pressure
decrease in cerebral oxygen consumption
18
Q
Propofol use for status epilepticus?
A
used off label for status epilepticus
suppresses seizure activity
19
Q
Propofol also exerts anti-emetic effects post-op, how?
A
depresses chemoreceptor trigger zone and vagal nuclei
20
Q
Cardiovascular effects of propofol?
A
causes vasodilation by inhibitis SNS vasoconstriction
can cause hypotension when given as a bolus
21
Q
What is PRIS?
A
propofol infusion syndrome
rare side effect of prolonged prop infusion (>4 mg/kg/hr >24 hrs)
22
Q
Clinical side effects of PRIS?
A
metabolic acidosis
hyperkalemia
hyperlipidemia
rhabdomyolysis
23
Q
Onset of PRIS?
A
usually within 4 days of initial treatment
24
Q
How do we manage PRIS?
A
discontinue prop
supportive care
25
Mortality of PRIS?
33%
26
Most commonly used IV benzos?
diazepam
lorazepam
midazolam
27
What do we use benzos for?
anxiety and amnesia
28
MOA of benzos?
inhibit synaptic transmission at GABA receptor
29
Can cause hyperlipidemia, pancreatitis, and local injection site pain;
prop
30
Does propofol have analgesic effects?
NO
31
Main disadvantages of prolonged propofol use?
high cost
| dose-related hypotension
32
Mechanism of this syndrome thought to be decreased fatty acid metabolism coupled with damage to mitochondria resulting in cardiac and peripheral myocyte dysfunction:
PRIS
33
Do benzos have analgesic effects?
NO
they are sedative anxiolytic
34
3 main benzos?
diazepam
lorazepam
midazolam
35
Diazepam AKA?
valium
36
How do benzos work?
increase frequency of Cl channel opening at GABA-A receptors
neuron becomes hyper-polarized, reduced neuron excitability
37
This benzo has short onset of action and short half-life,;
diazepam (valium)
38
Dose of diazepam (valium) for anxiety?
PO: 2-10 mg 2-4x/day
IV: 2-10 mg Q 3-4 hrs
39
Lorazepam AKA?
ativan
40
ATIVAN AKA?
lorazepam
41
This benzo has slow onset, intermediate half life and most useful for medium to long-term sedation:
lorazepam (ativan)
42
Lorazepam and the elderly?
can accumulate in older pts with renal and hepatic dysfunction causing prolonged sedation
43
Midazolam AKA?
versed
44
Benzo of choice for acutely agitated pts?
midazolam (versed)
45
Rapid onset, short acting benzo?
midazolam (versed)
46
Benzos when used with opioids tend to cause what?
respiratory depression
47
This is an imidazole derivative used to IV induction?
etomidate
48
Etomidate is rapidly and completely hydrolized to inactive metabolites, thus;
results in rapid awakening
49
Where does etomidate work?
GABA receptor
50
Effect of etomidate on BP and HR?
very iittle compared to propofol
51
What does ketamine do?
produces amnesia + analgesia
52
MOA of ketamine?
blocks NMDA receptors
53
What can ketamine cause in pts with CAD?
can increase HR and BP and cause ischemia in pts with CAD
54
Why is ketamine useful in asthmatic pts?
direct bronchodilator effect
55
Half life of ketamine?
10-15 mins
56
Ketamine elimination depends on?
liver CYP450 metabolism
57
Most common side effects of ketamine?
nausea/vomiting
58
Do we use ketamine in head trauma?
NO
| causes increased intracranial pressure
59
IV NSAID that produces analgesia by blocking COX:
ketorloac
60
Ketorolac blocks what?
COX-1 & COX-2
61
Side effects of ketorolac?
gastric bleeding
platelet dysfunction
liver/kidney damage
62
Analgesic and anti-pyretic that acts on CNS:
IV acetaminophen
63
Site of action of IV acetaminophen?
CNS
not peripherally
64
Addition of benzos to ketamine infusion has been shown to decrease what side effects?
delirium and hallucinations assc w/ketamine
65
What is dexmedetomidine?
sedative with analgesic properties
66
MOA of dexmedetomidine?
a2-adrenergic agonist
67
Side effects of dexmedetomidine?
hypotension
| bradycardia
68
What are the 3 opioids used in ICU setting?
fentanyl
morphine
hydromorphone
69
Advantages of fentanyl over morphine?
more rapid onset of action (600x more lipid soluble)
less risk of hypotension (fentanyl does not cause histamine release)
fent does not have active metabolites
70
Opioids are primarily metabolized in the ?
liver
and metabolites excreted in urine
71
Maintenance dose of morphine should be adjusted to 50% in pts with renal failure, why?
MS has several active metabolites that accumulate in the kidney
72
Does fentanyl need to be adjusted for pts with renal failure?
no, it does not have metabolites
73
How does MS cause hypotension?
promotes release of histamine
causes systemic vasodilation
74
Onset of morphine?
5-10 minutes
75
Onset of fentanyl?
1-2 minutes
76
Why is fentanyl better than morphine?
more lipid soluble
more rapid onset of action
no active metabolites
no need for renal adjustment
no histamine release--> no hypotension
77
Advantages of hydromorphone over morphine?
hydromorphone does not cause histamine release
| does not need to be adjusted in renal failure
78
Meperidine (demerol) is an opioid analgesic no longer used in ICU, why?
potential for neurotoxicity
| normeperidine is a metabolite that causes CNS excitation, myoclonus, delirium
79
Cardiovascular effects of opioids?
decrease HR and BP due to decrease in SNS activity
BP responds to fluid boluses or pressor boluses
80
Opioid effects in GI motility?
depressed GI motility via opioid receptors in GI tract
81
How do opioids cause vomiting?
stimulate chemoreceptor trigger zone
82
Why are IV doses of ketorlac preferred over IM?
IM doses can cause hematomas
83
Recommended dosage of ketorolac?
30 mg IV Q 6 hrs
reduce it to 15 mg IV Q 6 hrs for elderly or pts with body weight <50kg
84
Adverse rxns with ketorolac?
gastric mucosal injury
upper GI bleed
renal function impairment
85
Maximum daily dose of ibuprofen?
3.2 grams
86
Maximum allowed dose of IV acetaminophen?
4 grams daily
***to prevent acetaminophen hepatoxicity
87
How do we measure agitation in the ICU?
sedation agitation scale SAS
richmond agitation severity score RASS
88
Preferred benzo for rapid sedation?
midazolem (versed)
89
Onset of action of midazolem (versed)?
1-2 minutes due to its high lipid solubility
90
Effects of midazolam (versed) last how long?
1-2 hrs (cleared rapidly from blood stream and taken avidly into tissue)
91
Why do we limit midazolam (versed) infusion to less than 48 hrs?
prevents excessive sedation from drug accumulation in tissues
92
Lorazepam (ativan) is a longer acting drug that midazolam, with effects up to?
6 hrs after a single dose
93
The IV preparation of lorazepam contains what?
propylene glycol (a solvent which increased drug solubility)
its toxic when it accumulates
94
Midazolam vs loparezepam, which has a metabolite?
midazolam has a metabolite --> cleared by the kidneys
95
Why can changes in renal function affect midazolam?
has a metabolite that's cleared by the kidneys
96
Benzos are metabolized where?
liver
97
Onset of action of midazolam vs lorazepam:
midazolam; 2-5 mins
lorazepam; 15-20 mins
98
Toxicity assc with midazolam vs lorazepam:
midazolam; metabolite toxicity in renal impaired pts
lorazepam; propylene glycol toxicity
99
What is propylene glycol toxicity seen with lorazepam?
IV preparations of lorazepam contain propylene glycol to enhance solubility
converted to lactic acid in the liver
causes; lactic acidosis, delirium, hypotension, multi-organ failure
100
AN unexplained metabolic acidosis after > 24 hrs of lorazepam should prompt evaluation for?
serum lactate levels
raise suspicion for propylene glycol toxicity
101
Onset of action of prop?
1-2 minutes
102
Arousal after prop wears off?
10-15 mins
103
Adverse effects of prop?
Hypotension
Hyperlipidemia
PRIS
respiratory depression
104
Why can we use propofol in pts with intracranial injuries?
reduces intracranial pressures
allows for frequent arousal to check mental status
105
How is propofol dose?
dose for IBW
not adjusted for renal failure or moderate liver failure
106
Prop is suspended in what?
10% lipid emulsion to enhance plasma solubility
107
Green urine with prop?
rare
due to phenolic metabolites
108
Prop well known for producing what?
resp depression
hypotension
(should be ideally started in pt's that are vented)
109
How to avoid risk of PRIS?
avoid prop infusion rates > 5mg/kg/hr for more than 48 hrs
110
This is an a2-receptor agonist that produces sedative, amnestic and mild analgesic effect;
dexmedtomidine
111
Onset of action of dex?
5-10 mins
| time to arousal; 6-10 mins
112
Does dex cause respiratory depression like prop?
NO
113
What's so nice about dex?
patients can be aroused even though they're sedated., don't need to stop the infusion
when awake pt's can communicate and follow commands
114
Why is dex good for vented pts?
sedation can be continued from transition period from mechanical ventilation to spontaneous breathing
115
Adverse effects of dex?
dose dependent decrease in HR, BP
116
How does haldol work?
produces its sedative and antipsychotic effects by blocking dopamine receptors in brain
117
Onset of haldol?
10-20 mins
lasts 3-4 hrs
118
Does haldol cause respiratory depression?
NO
hypotension rare
119
Extrapyramidal effects of haldol?
rare with IV administration (seen with PO)
| rigidity, spasmodic rxns
120
Neuroleptic malignant syndrome seen with what drug?
IV haldol
rare
(fever, muscle rigidity, rhabdo)
121
Why do we avoid haldol in pts with prolonged qtC?
haldol prolongs Qtc
causes polymorphic vtach like torsades
