PHARMACOLOGY | IV Anesthetics Part I Flashcards
This is defined as the time to achieve a 50% reduction in concentration after stopping a continuous infusion:
A. Context-sensitive halftime
B. Elimination half-life
C. Bioavailability
A. Context-sensitive halftime
Reduction in concentration AFTER stopping the CONTINUOUS infusion
The following are pharmoco-properties IDEAL for IV anesthetics EXCEPT:
A. It should be water-soluble and stable
B. No tissue damage with extravasation
C. Low incidence of histamine release or hypersensitivity
D. Slow onset and predictable duration
E. Rapid metabolism to inactive metabolites
D. Slow onset and predictable duration - False statement
ideally it must be fast onset!
Which of the following is MOST accurate regarding the IV anesthetic and its effect on the CNS?
A. GABA is the primary excitatory neurotransmitter in CNS
B. Activation of GABA causes increase in chloride conductance, and therefore hyperpolarization of neuron
C. Benzodiazepines decreases the frequency of chloride channel openings
D. glutamate, glycine, and D-serine are major inhibitory neurotransmitter
B. Activation of GABA causes increase in chloride conductance, and therefore hyperpolarization of neuron
Which of the following is MOST accurate regarding the clinical effects of Propofol:
A. It can produce bronchodilation in patients with
COPD
B. Propofol inhibits pulmonary vasoconstriction
C. It does not exhibit myoclonus like that of thiopental
D. Fospropofol is a prodrug of Propofol which has a faster onset and longer duration
A. It can produce bronchodilation in patients with
COPD
This is the time it takes for the plasma concentration of a drug to decrease to 50% of its
original concentration:
A. Context-sensitive halftime
B. Elimination half-life
C. Bioavailability
D. Volume of distribution
B. Elimination half-life
This concept works well to describe a one compartment model for a drug distributed only to the blood, or if the drug is administered only once.
In contrast, pharmacokinetic modeling that describes intravenous anesthetics administered by infusion needs to account for multiple compartments, phases of distribution, and elimination.
TRUE or FALSE
Thiopental has a LOWER context-sensitive half-time compared to Propofol.
FALSE
In comparison to thiopental, propofol has a much lower context-sensitive half-time. Although, the elimination of propofol is prolonged with longer infusions, it is not to the same magnitude as with thiopental.
It is the low context-sensitive half-time that allows for propofol to be used as a continuous infusion.
Which of the following is MOST accurate regarding the pharmacodynamic of Propofol?
A. a state of paradoxical excitation is expected at the start of low dose
B. it acts primarily via inhibition of gamma-aminobutyric acid-A (GABA-A) pathways
C. Propofol binds post-synaptically and enhances GABA-nergic inhibition
D. Burst suppression is not expected even with low dose
C. Propofol binds post-synaptically and enhances GABA-nergic inhibition
- The mechanism by which the unconscious state is attained by Propofol is complicated, but primarily occurs via enhancement
of gamma-aminobutyric acid (GABA) inhibitory pathways.
TRUE or FALSE
The rapid onset of ETOMIDATE is due to high lipid solubility and large non-ionized fraction at physiologic pH
TRUE
Non-ionized = RAPID onset
High lipid solubility = RAPID onset
TRUE or FALSE
Propofol shortens seizure duration
TRUE
It has also been used successfully to treat status epilepticus, thus it is rarely the anesthetic of choice during induction of anesthesia for electroconvulsive therapy (ECT) because it SHORTENS seizure duration.
TRUE or FALSE
The loss of consciousness attributed to propofol can be partially reversed physostigmine.
TRUE
The effects of ketamine related to pain can be best described as:
A. antihyperalgesic, antiallodynic, or tolerance protective
B. antihyperalgesic only
C. antiallodynic but NOT tolerance protective
A. antihyperalgesic, antiallodynic, or tolerance protective
Which of the following statement is ACCURATE in terms of the pharmaco-property of Ketamine:
A. Ketamine is a racemic mixture and R(-) is more potent than S(+)
B. Ketamine is secreted in the urine with a half-life of 2-3 hrs
C. Ketamine has high protein binding
D. Norketamine is the metabolite of ketamine and has no effect
B. Ketamine is secreted in the urine with a half-life of 2-3 hrs - TRUE statement
Which form of KETAMINE is more potent?
A. S(+) enantiomer
B. R(+) enantiomer
A. S(+) enantiomer
MORE potent, SHORTER duration, cleared RAPIDLY
The S(+) enantiomer of ketamine is three to four times more potent than the R enantiomer. The S enantiomer has a shorter duration of action and is cleared more rapidly.
Why is it needed to decrease the DOSE of ketamine in patients with severe critical illness?
Ketamine has INTRINSIC myocardial depressant hence, in severely ill patients with DEPLETED catecholamine reserves, it is crucial to lower the dose to minimize the myocardial depressant effect!
Which is MOST accurate regarding KETAMINE:
A. Ketamine is a racemic mixture and the R(-) enantiomer is considered more potent than S(+)
B. Norketamine is eliminated primarily by hepatobiliary excretion
C. Ketamine has poor protein binding
D. Norketamine is the metabolite of ketamine and has no clinical effect
C. Ketamine has poor protein binding
The high lipid solubility and low protein binding (20%) allow for a rapid uptake of ketamine in the brain, as well as a fairly rapid redistribution.
ONSET: 15 - 30 seconds
DURATION: 10 - 15 minutes
Benzodiazepines act on GABA-A and produce a net effect by:
A. Increase in Cl conductance
B. Decrease in Cl conductance
C. Increases duration of Cl channel opening
D. Decreases duration of Cl channel opening
A. Increase in Cl conductance
The mechanism of action of Barbiturates on Cl channel is:
A. Increase duration of chloride channel opening
B. Decrease duration of chloride channel opening
C. Increase Cl conductance
D. Decrease Cl conductance
A. Increase duration of chloride channel opening
The sense of well being “euphoria” from Propofol is primarily attributed to:
A. Increase of Dopamine in NUCLEUS ACCUMBENS
B. Decrease of Dopamine in NUCLEUS ACCMBENS
C. GABA-B potentiation
A. Increase of Dopamine in NUCLEUS ACCUMBENS
After a single bolus of PROPOFOL, the plasma level decreases immediately thru:
A. Redistribution
B. Extrahepatic clearance
A. Redistribution
Propofol increases the duration of action of Midazolam. This is due to which mechanism?
A. Competitive inhibition of CYP3A4
B. Extrahepatic metabolism of propofol
C. Decrease dopamine in the nucleus accumbens
A. Competitive inhibition of CYP3A4
If propofol is administered via continuous IV infusion for 3 - 8 hours, it’s context-sensitive half-time will be:
A. 40 mins
B. 10 mins
C. 1 hour
D. 2 hours
A. 40 mins
What is the effect of HYPOTENSION to the clearance of Propofol?
- Decrease CO > Decrease liver blood flow > reduce the rate of clearance > therefore, it PROLONGS the duration of ACTION
TRUE or FALSE
Propofol decreases CPP but NO EFFECT on cerebral autoregulation?
TRUE
At a maintenance rate, Propofol infusion will have the following effect on lung mechanics?
A. Decrease RR
B. Increase RR
C. Increase TV
B. Increase RR
During induction dose, a single bolus of PROPOFOL will have a dose-dependent APNEA however, with continuous IV infusion, RR will have a 20& increase and TV will decrease.
Induction dose of Propofol is based on?
A. actual body weight
B. total body weight
C. lean body weight
C. lean body weight
Propofol produces a dose-dependent decrease in blood pressure without compensatory elevation of the heart rate (tachycardia). This is due to:
A. Inhibition of baroreceptor reflex
B. Inhibition of chemo receptor
C. Bainbridge reflex
A. Inhibition of baroreceptor reflex
Propofol Infusion Syndrome is highly associated with this plasma dose:
A. >70 mcg/kg.min
B. >50 mcg/kg/min
C. >30 mcg/kg/min
A. >70 mcg/kg.min
The most apparent effect of Propofol on SSEP monitoring:
A. Increase latency, decrease amplitude
B. Decrease latency, decrease amplitude
C. Increase latency, Increase amplitude
A. Increase latency, decrease amplitude
TRUE or FASLE
Propofol SUPPRESS atrial tachycardia
TRUE!
The most common extra-hepatic elimination of Propofol is thru:
A. Lungs
B. Kidney
C. Heart
D. Esterases
A. Lungs
Comparing the induction dose of thiopental vs propofol, an inducting dose of propofol produces:
A. Better maintenance of cerebral perfusion pressure
B. Greater inhibition of glucocorticoid production
C. Higher incidence of myoclonus
D. Less severe hypotension
E. Less severe respiratory depression
C) Higher incidence of myoclonus
Which of following is known effect of propofol?
A. Decrease amplitude of SSEP
B. Induces malignant hyperthermia
C. Inhibition of cytochrome p450
D. Initiation of porphyria
E. Inhibition of glucocorticoid function
A. Decrease amplitude of SSEP - Correct answer
B. Induces malignant hyperthermia - (volatiles, succinylcholine)
C. Inhibition of cytochrome p450 - (several, but not propofol)
D. Initiation of porphyria - (variety of drugs, but not propofol)
E. Inhibition of glucocorticoid function - this is etomidate
TRUE or FALSE
Propofol significantly inhibits hypoxic pulmonary vasoconstriction
FALSE!
Does not INHIBIT HPV.
TRUE or FALSE
The unconsciousness attained by PROPOFOL is thru inhibition of GABA pathways.
FALSE!
The mechanism by which the unconscious state is attained by Propofol is complicated, but primarily occurs via enhancement
of gamma-aminobutyric acid (GABA) inhibitory pathways.
Components of PROPOFOL except:
A. 2.5% glycerol
B. 1.2 % egg phospholipid
C. 10 % soybean oil
D. EDTA
E. 10% Propofol
E. 10% Propofol - only 1% of PROPOFOL!
PROPOFOL consists:
1% propofol
1.2% egg phospholipid
2.25% glycerol
10% soybean oil
emulsifier
ethylenediamenetetraacetic acid (EDTA)
TRUE or FALSE
Propofol binds pre-synaptically and enhances GABAergic inhibition.
FALSE!
Propofol binds post-synaptically and enhances GABAergic inhibition.
Unconsciousness occurs as this enhanced GABAergic inhibition counteracts
ascending arousal inputs to the pyramidal neuron and decreases excitatory activity.
EEG activity tracing with the induction dose of PROPOFOL:
A. increase in alpha and delta activity
B. beta-wave activity is dominant
C. decrease both aplha and delta activity
A. increase in alpha and delta activity
Plasma concentrations needed to reach the initial stages of general anesthesia with PROPOFOL:
A. 3 mcg/mL
B. 8 mcg/mL
C. 5 mcg/mL
A. 3 mcg/mL
8 mcg/mL - BURST SUPRESSION is achieved with this plasma level
TRUE or FALSE
Propofol has specific antioxidant properties
TRUE
Why is Propofol not an ideal agent for ECT?
A. It shortens the duration of seizure
B. It arrests the seizure threshold
C. It lengthens the duration of seizure
- It shortens the duration of seizure
It has also been used successfully to treat status epilepticus, thus it is rarely the anesthetic of choice during induction of anesthesia for electroconvulsive therapy (ECT) because it shortens seizure duration.