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IV anesthetics

Pharm (Test 3)

QuestionAnswer
Which drug is the "gold standard" for IV anesthetics? pentothal/thiopental
IV anesthetics are also known as... (3) 1)IV induction agents, 2)sedatives, 3)hypnotics
Which IV anesthetic is referred to as a "dissociative drug"? ketamine
True or False: IV anesthetics, typically, are drugs injected to induce unconsciousness at the beginning of general anesthesia, but allows rapid recovery after the end of its effect. True
How do IV anesthetics alter a pt's level of consciousness? by depressing the reticular activating system either by 1)enhancing the inhibition properties of GABA or 2)inhibiting the NMDA excitatory synapses
Which 2 IV anesthetics can be used for TIVA? propofol or ketamine
How much CO does the vessel-rich group (brain, heart, liver, kidneys, endocrine) receive? 75%
How much CO does the lean muscle group (muscle, skin) receive? 19%
How much CO does the fat group receive? 6%
How much CO does the vessel-poor group (bone, ligament, cartilage) receive? 0%
What term describes the time in which the drug starts losing it's effect? redistribution 1/2 time
What term describes the time when the drug actually exits the body? elimination 1/2 time
What is the primary mechanism for terminating the central effect of IV induction agents? their redistribution from the central, highly perfused compartment to the larger, less-well perfused "peripheral" compartments
What is the "alpha" phase of metabolism? redistribution -- the plasma concentration of the drug has declined to the point that the drug moves out of the vessel-rich central group and is then taken into the peripheral group
What is the "beta" phase of metabolism? elimination -- involves metabolism and excretion
Equilibrium with skeletal muscles is reached in about ______min after IV injection of thiopental. 15min
True or False: Large or repeated doses of lipid-soluble barbiturates produce a cumulative effect because of storage capacity of fat. True
What are the only IV anesthetics that enhances opioid analgesia? ketamine, dexmetetomidine, and propofol
What class of drug is pentothal/thiopental? barbiturate (sulfur)
What is the preparation of thiopental? 2.5% sodium salt preparation
Thiopental is (lipid or water?) soluble in preparation. water
What is the pH of prepared thiopental? 10.5 (highly alkaline)
How does the alkalinity of thiopental act as an advantage? bacteriostasis -- bacteria can't grow like in propofol
Thiopental is (stable or unstable?) once reconstituted? unstable; lasts only 6days at room temp and 2 weeks in frig
Which drugs can precipitate when mixed with thiopental? opioids, catecholamines, NMB (NMB will turn thiopental to concrete)
Does thiopental cause pain on injection? minimal
True or False: Thiopental forms crystals when injected arterially. True
What is the mechanism of action of pentothal? 1) increases duration of GABA activating its receptor, causing Cl- channels to remain open, hyperpolarizing membrane, 2) mimics GABA at its own receptor, causing Cl- channels to open, 3)activates glutamate, adenoside, and nACh receptors
Which mechanism of action of pentothal causes the hemodynamic effects? SNS ganglia depressed transmission
Thiopental (sensitizes or desensitizes?) nACh receptors to the depolarizing effects of ACh. desensitizes
How dangerous are pentothal's CV effects compared to other drugs of this class? minimal
What are thiopental's CV effects? transient dec. in BP, accompanying inc. in HR, peripheral dilation (venous pooling, dec. venous return), less myocardial depressive effects than volatiles
How much does a 5mg/kg dose of pentothal affect BP and HR? 10-20mmHg dec. in BP, 15-20 beat inc. in HR
Does pentothal cause histamine release? possibly
True or False: Slowing the rate of administration of pentothal can dec. the CV changes. False
What are thiopental's respiratory effects? dec. sensitivity if medullary ventilator center to stimulation of CO2, apnea more likely when given w/ opioids/benzos, resp. returns as small TV and slow RR
How does thiopental affect airway reflexes? reflexes remain intact, possibility of laryngospasm
Thiopental (increases or decreases?) ICP. decreases (cerebral vasoconstriction which decreases cerebral blood flow)
Thiopental decreases CMRO2 by _____%. 55% (the most of our drugs)
What types of cerebral ischemia can be protected by thiopental? incomplete cerebral ischemia (coronary bypass, hypotension, circ. arrest)
What types of cerebral ischemia cannot be protected by thiopental? global cerebral ischemia (cardiac arrest)
What dose of thiopental can cause isoelectric EEG? 37.5mg/kg
Does thiopental cause liver or kidney damage? no (slight dec. in flow d/t dec. BP/CO)
Can thiopental be given to pt's w/ porphyria? no (stim. and inc. production of heme --> acute intermittent porphyria may be exacerbated)
Thiopental (does or doesn't?) cross placenta? does
Can thiopental lead to tolerance and dependence? yes
Can thiopental lead to anaphylaxis and anaphylactoid reactions? yes
What is thiopental's distribution 1/2 time? 2-4 min
What is thiopental's elimination 1/2 time? 10-12 hrs
True or False: Thiopental is water-soluble in preparation and lipid-soluble at physiologic pH. True
_____% of thiopental is protein bound. 85%
What is the dose of thiopental? 3-5mg/kg
What is pentothal's onset? 30 sec
What is thiopental's duration? 5-10 min
Does thiopental cause a "hangover"? yes
What are some advantages to using thiopental? minimal CV effects, minimal pain on injection, good cerebral protection (55%), possible isoelectric EEG
What are some disadvantages to using thiopental? dec. resp response to CO2, airway reflexes remain intact, hangover, moderate emetic, precipitation, can't give to pts w/ porphyria, crosses placenta, tolerance/dependence, anaphylaxis, unstable reconstituted
What class of drug is brevital/methohexital? barbiturate (oxybarbiturate)
How is methohexital prepared? 1% solution
Brevital is (stable or unstable?) reconstituted? stable (6wks in frig)
What is methohexital's MOA? GABA (like thiopental)
How does methohexital's lipid-solubility compare to pentothal? less lipid soluble
How does methohexital's metabolism compare to pentothal? 3-4X faster (d/t dec. lipid solubility, smaller vol. of dist.)
How does methohexital's hangover compare to pentothal? less hangover
How does methohexital's awakening time compare to pentothal? faster
What is brevital's elimination 1/2 time? 3.9 hrs (2-5 hrs)
What are the CV effects of methohexital? similar to thiopental (maybe less hTN d/t inc. in HR better preserved)
Does methohexital cause histamine release? no
Can methohexital cause exascerbation of acute intermittent porphyria? yes
What are some advantages to brevital? more rapid recovery than thiopental, good CV profile, cerebral protection (not as much as thiopental), less hangover than thiopental
What are some disadvantages to methohexital? exascerbation of acute intermittent porphyria, more excitatory activity, myoclonus, hiccoughs, moderate emetic
How does methohexital's potency compare to thiopental? 2.5X more potent (d/t less lipid solubility)
True or False: Methohexital's excitatory activities are dose-dependent. True
How can you decrease incidence of brevital's excitatory activity, myoclonus, hiccoughs? inclusion of opioids pre-op and dose of 1-1.5 mg/kg of brevital
What is an induction dose of methohexital? 1-2mg/kg
What is a sedation dose of methohexital? 0.2-0.4mg/kg
What is a rectal dose of methohexital? 25mg/kg
What is the onset of brevital? 30sec
What is the duration of methohexital? 5-10 min
What is the distribution 1/2 time of methohexital? 5.6 min
True or False: Etomidate is chemically unrelated to any other IV anesthetic. True
True or False: Etomidate has a carboxylate imidazole-containing compound (water-soluble at acidic pH and lipid soluble at physiologic pH). True
How is etomidate prepared? 0.2% in propylene glycol
What is prepared etomidate's pH? 6.9
Does etomidate cause pain on injection? yes (propylene glycol)
What is etomidate's MOA? mimics inhibitory effects of GABA by increasing the receptors affinity to GABA, thus depresses the reticular activating system
What is the incidence of excitatory activity to cause myoclonus w/ etomidate? 30-60%
What are etomidate's CV effects? dec MAP (15%, minimal), minimal changes in HR, SV, CO, dec in SVR, depressed myocardium less than thiopental, no dec. in renal blood flow
Does etomidate cause histamine release? no
How does etomidate's resp effects compare to barbiturates? less resp effects
What are etomidate's resp effects? dec. TV, but inc. RR, apnea doesn't always occur, apnea more likely w/ opioids/benzos/volatiles
Etomidate dec. CMRO2 by _______%. 35-45%
True or False: Etomidate should be avoided in pts w/ seizure disorders. True (d/t excitatory activity)
What are some advantages to etomidate? best CV profile, less resp effects (not always apnea), cerebral protection (35-45% dec in CMRO2)
What are some disadvantages to etomidate? excitatory activity (avoid in seizure pts), adrenocortical suppression (avoid in septic and bleeding pts), commonly emetic, pain on injection
How does etomidate cause adrenocortical suppression? inhibition of the conversion of cholesterol to cortisol (inhibition of the enzyme which performs 11-beta-hydoxylation reaction)
How quickly does etomidate dec. cortisol and aldosterone levels? 30min after single dose
How long does the adrenocortical suppression from etomidate last? 4-8 hrs after dose (up to 48hrs)
True or False: Pretreating w/ a dose of steroid before dose of etomidate can prevent adrenocortical suppression. False
Etomidate's action is limited by... redistribution
Compare etomidate's metabolism to that of thiopental. 5X faster
What is the dose of etomidate? 0.3mg/kg
What is the onset of etomidate? 14-45sec
What is the duration of etomidate? 3-12min
What is the distribution 1/2 time of etomidate? 2-4 min
What is the elimination 1/2 time of etomidate? 2-5 hrs
What class of drug is dexmetetomidine/precedex? alpha2 adrenergic agonist
What is precedex's MOA? (in spinal cord and locus coeruleus) hyperpolarization with efflux of K+, reduced NE release d/t presynaptic receptors, dec. cAMP cntn by inhibiting adenylyl cyclase
True or False: Precedex is often used for induction? False (prob. not ever)
What are dexmetetomidine's CV effects? hypertension (r/t loading dose), dec. HR, BP (possible heart block)
What are some advantages to dexmetetomidine? sedation/analgesia w/ little vent. depression, less delirium than benzos, sedation similar to sleep, wean vent w/o titration, easily arousable, dec. MAC by 90%, antisialogauge, some analgesic effect, reduces shivering
True or False: Dexmetetomidine is not approved for general anesthesia. True
True or False: Precedex is a good alternative to ketamine for awake fiberoptic intubation. True
What is the distribution 1/2 life of precedex? 6-8 min
What is the context sensitive 1/2 time of dexmetetomidate? after 1 hr=25-120min, after >6hrs=87-250 min
What is a loading dose of dexmetetomidine? 0.5-1mcg/kg over 10 min
What is the infusion dose of dexmetetomidine? 0.2-1.4mcg/kg/hr
Which IV anesthetic has the worst resp effects? propofol
Which IV anesthetic supports spont resp? ketamine
Which IV anesthetic is the least resp depressant? etomidate
Which IV anesthetic has the worst hangover? pentothal
Which IV anesthetic has the least hangover? propofol
Which IV anesthetic can cause hallucinations? ketamine
Which IV anesthetic is the only antiemetic? propofol
Which IV anesthetic is the worst emetic? etomidate
Which IV anesthetic affect adrenocortical function? etomidate
Which IV anesthetics shouldn't be used on pt's with acute intermittent porphyria? pentothal and brevital
Which IV anesthetic causes HTN w/ loading dose? dexmetetomidine
Which IV anesthetics cause excitatory activity? brevital and etomidate
Which IV anesthetic contains and imidazole-containing compound? etomidate
Which IV anesthetic can achieve an isoelectric EEG? pentothal
Which IV anesthetic reduces shivering? dexmetetomidine/precedex