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Questions and Answers
Propofol can be slowly released from a peripheral compartment, which does not interfere with awakening from a bolus dose or infusion.
Propofol can be slowly released from a peripheral compartment, which does not interfere with awakening from a bolus dose or infusion.
True (A)
Propofol dosing for unconsciousness is at 2-6 μg/ml.
Propofol dosing for unconsciousness is at 2-6 μg/ml.
True (A)
Morbidly obese patients should be dosed based on their total body weight.
Morbidly obese patients should be dosed based on their total body weight.
False (B)
Elderly patients require a 25-50% increase in propofol dose.
Elderly patients require a 25-50% increase in propofol dose.
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Propofol has a context-sensitive half-time due to its rapid effect-site equilibration.
Propofol has a context-sensitive half-time due to its rapid effect-site equilibration.
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The SEDASYS computer-assisted sedation system is approved by the FDA for use in colonoscopy and EGD with the requirement for a trained anesthesia provider.
The SEDASYS computer-assisted sedation system is approved by the FDA for use in colonoscopy and EGD with the requirement for a trained anesthesia provider.
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Propofol has an antiemetic effect and can be used to reduce postoperative nausea and vomiting in PACU.
Propofol has an antiemetic effect and can be used to reduce postoperative nausea and vomiting in PACU.
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Propofol has an antipruritic effect and is effective in treating neuraxial opioid-associated pruritis.
Propofol has an antipruritic effect and is effective in treating neuraxial opioid-associated pruritis.
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Propofol has anticonvulsant activity and can terminate generalized seizure activity.
Propofol has anticonvulsant activity and can terminate generalized seizure activity.
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Propofol can attenuate bronchoconstriction and is appropriate for use in asthmatic patients.
Propofol can attenuate bronchoconstriction and is appropriate for use in asthmatic patients.
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Propofol has analgesic effects and is beneficial in acute nociceptive pain.
Propofol has analgesic effects and is beneficial in acute nociceptive pain.
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Propofol has been shown to reduce cerebral blood flow and intracranial pressure.
Propofol has been shown to reduce cerebral blood flow and intracranial pressure.
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Etomidate can benefit patients with elevated intracranial pressure (ICP)
Etomidate can benefit patients with elevated intracranial pressure (ICP)
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Etomidate reduces cerebral blood flow by up to 35%
Etomidate reduces cerebral blood flow by up to 35%
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Etomidate inhibits cortisol and mineralocorticoid production for up to 72 hours after a single induction dose
Etomidate inhibits cortisol and mineralocorticoid production for up to 72 hours after a single induction dose
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Etomidate derivatives, such as methoxycarbonyletomidate and carboetomidate, have similar structures and pharmacological properties compared to etomidate
Etomidate derivatives, such as methoxycarbonyletomidate and carboetomidate, have similar structures and pharmacological properties compared to etomidate
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Etomidate has a high incidence of postoperative nausea and vomiting (PONV) when given with narcotics
Etomidate has a high incidence of postoperative nausea and vomiting (PONV) when given with narcotics
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Etomidate acts as a negative allosteric modulator of the γ-aminobutyric acid-A (GABA) receptor
Etomidate acts as a negative allosteric modulator of the γ-aminobutyric acid-A (GABA) receptor
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Etomidate has a similar volume of distribution to other benzodiazepines
Etomidate has a similar volume of distribution to other benzodiazepines
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Etomidate has neuroprotective activity, which is well-documented in humans
Etomidate has neuroprotective activity, which is well-documented in humans
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Etomidate can cause apnea in large doses
Etomidate can cause apnea in large doses
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Flumazenil acts as a competitive antagonist, preventing or reversing the effects of other benzodiazepines in a dose-dependent manner
Flumazenil acts as a competitive antagonist, preventing or reversing the effects of other benzodiazepines in a dose-dependent manner
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Flumazenil is used for reversing residual benzodiazepine-induced sedation
Flumazenil is used for reversing residual benzodiazepine-induced sedation
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Flumazenil has a slow clearance rate
Flumazenil has a slow clearance rate
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Barbiturates directly activate the opening of chloride channels at low concentrations
Barbiturates directly activate the opening of chloride channels at low concentrations
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Barbiturates induce peripheral vasoconstriction
Barbiturates induce peripheral vasoconstriction
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Barbiturates have been shown to be superior to other techniques for decreasing ICP following acute brain injury
Barbiturates have been shown to be superior to other techniques for decreasing ICP following acute brain injury
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Barbiturates were previously used for neuroprotection in procedures like carotid endarterectomy
Barbiturates were previously used for neuroprotection in procedures like carotid endarterectomy
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Barbiturates can function as anticonvulsants at higher concentrations
Barbiturates can function as anticonvulsants at higher concentrations
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Barbiturates are contraindicated in severe cardiovascular instability or shock
Barbiturates are contraindicated in severe cardiovascular instability or shock
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Thiopental has been described as having an antianalgesic effect at low blood levels
Thiopental has been described as having an antianalgesic effect at low blood levels
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Barbiturates are commonly used as a recreational drug
Barbiturates are commonly used as a recreational drug
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Thiopental infusions are used to treat status epilepticus
Thiopental infusions are used to treat status epilepticus
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Barbiturates dosages must be increased in premedicated patients
Barbiturates dosages must be increased in premedicated patients
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Barbiturates can affect pregnancy by increasing the volume of the central compartment
Barbiturates can affect pregnancy by increasing the volume of the central compartment
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Methohexital dosing for status epilepticus is approximately 2 mg/kg
Methohexital dosing for status epilepticus is approximately 2 mg/kg
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Ketamine has been used in low doses to induce seizure discharges in temporal lobe epilepsy.
Ketamine has been used in low doses to induce seizure discharges in temporal lobe epilepsy.
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The S(+) isomer of ketamine has 4x greater affinity for the phencyclidine binding site on the NMDA receptor than the R(-) isomer.
The S(+) isomer of ketamine has 4x greater affinity for the phencyclidine binding site on the NMDA receptor than the R(-) isomer.
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Ketamine has analgesic effects due to its strong binding to mu opioid receptors.
Ketamine has analgesic effects due to its strong binding to mu opioid receptors.
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R(-) ketamine is available in Europe but not in the United States.
R(-) ketamine is available in Europe but not in the United States.
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Ketamine produces a dissociative state resulting in intense analgesia and amnesia.
Ketamine produces a dissociative state resulting in intense analgesia and amnesia.
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Ketamine binds with multiple CNS receptors, including NMDA, opioid, and muscarinic receptors.
Ketamine binds with multiple CNS receptors, including NMDA, opioid, and muscarinic receptors.
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Ketamine's rapid onset of action is due to its low lipid solubility.
Ketamine's rapid onset of action is due to its low lipid solubility.
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The major pathway for ketamine metabolism leads to the active metabolite norketamine.
The major pathway for ketamine metabolism leads to the active metabolite norketamine.
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Ketamine has a long duration of action due to its extensive protein binding.
Ketamine has a long duration of action due to its extensive protein binding.
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Ketamine can speed delivery of the drug to the brain through increased cerebral blood flow.
Ketamine can speed delivery of the drug to the brain through increased cerebral blood flow.
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Propofol is insoluble in aqueous solution.
Propofol is insoluble in aqueous solution.
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Propofol is excreted by the liver.
Propofol is excreted by the liver.
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Propofol is provided in an emulsion containing 1% propofol, 10% soybean oil, 2.25% glycerol, and 1.2% purified egg phosphatide.
Propofol is provided in an emulsion containing 1% propofol, 10% soybean oil, 2.25% glycerol, and 1.2% purified egg phosphatide.
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Propofol has a context-sensitive half-time of less than 40 minutes for infusions up to 8 hours duration.
Propofol has a context-sensitive half-time of less than 40 minutes for infusions up to 8 hours duration.
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Propofol has anticonvulsant activity and can terminate generalized seizure activity.
Propofol has anticonvulsant activity and can terminate generalized seizure activity.
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Propofol clearance exceeds hepatic blood flow.
Propofol clearance exceeds hepatic blood flow.
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Propofol has been shown to reduce cerebral blood flow and intracranial pressure.
Propofol has been shown to reduce cerebral blood flow and intracranial pressure.
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Propofol has analgesic effects and is beneficial in acute nociceptive pain.
Propofol has analgesic effects and is beneficial in acute nociceptive pain.
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Propofol has an antiemetic effect and can be used to reduce postoperative nausea and vomiting in PACU.
Propofol has an antiemetic effect and can be used to reduce postoperative nausea and vomiting in PACU.
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Propofol dosing for unconsciousness is at 2-6 μg/ml.
Propofol dosing for unconsciousness is at 2-6 μg/ml.
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Midazolam undergoes first-pass metabolism before reaching systemic circulation
Midazolam undergoes first-pass metabolism before reaching systemic circulation
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The primary metabolite of midazolam is 1-hydroxymidazolam, which has approximately 50% activity of the parent compound
The primary metabolite of midazolam is 1-hydroxymidazolam, which has approximately 50% activity of the parent compound
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Midazolam clearance is 10 times greater than that of diazepam and 5 times greater than that of lorazepam
Midazolam clearance is 10 times greater than that of diazepam and 5 times greater than that of lorazepam
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Midazolam is typically used for preoperative anxiolysis and sedation, with a slower onset than thiopental or propofol, but reliable amnesia
Midazolam is typically used for preoperative anxiolysis and sedation, with a slower onset than thiopental or propofol, but reliable amnesia
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Lorazepam has a lower lipid solubility, resulting in a delayed onset of effect in the CNS
Lorazepam has a lower lipid solubility, resulting in a delayed onset of effect in the CNS
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Lorazepam has a higher affinity for GABA receptors compared to diazepam, resulting in longer-lasting effects despite higher clearance and similar volume of distribution
Lorazepam has a higher affinity for GABA receptors compared to diazepam, resulting in longer-lasting effects despite higher clearance and similar volume of distribution
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Lorazepam has been shown to reduce cerebral blood flow and intracranial pressure
Lorazepam has been shown to reduce cerebral blood flow and intracranial pressure
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Lorazepam is metabolized via hepatic glucuronidation to inactive metabolites, relatively unaffected by inhibition of cytochrome P-450 or changes in hepatic function
Lorazepam is metabolized via hepatic glucuronidation to inactive metabolites, relatively unaffected by inhibition of cytochrome P-450 or changes in hepatic function
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Midazolam is insoluble in water and is dissolved in organic solvents such as propylene glycol and sodium benzoate
Midazolam is insoluble in water and is dissolved in organic solvents such as propylene glycol and sodium benzoate
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Lorazepam has been used for induction at a dose of 0.1 mg/kg and maintenance at a dose of 0.02 mg/kg prn
Lorazepam has been used for induction at a dose of 0.1 mg/kg and maintenance at a dose of 0.02 mg/kg prn
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Midazolam can accumulate in renal insufficiency and may have delayed elimination in the presence of drugs that inhibit cytochrome P450, such as cimetidine, erythromycin, and calcium channel blockers
Midazolam can accumulate in renal insufficiency and may have delayed elimination in the presence of drugs that inhibit cytochrome P450, such as cimetidine, erythromycin, and calcium channel blockers
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Lorazepam has been described as having an antiemetic effect and can be used to reduce postoperative nausea and vomiting in PACU
Lorazepam has been described as having an antiemetic effect and can be used to reduce postoperative nausea and vomiting in PACU
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Study Notes
- Barbiturates act on GABAA receptors: At low concentrations, they enhance the effect of GABA and decrease its dissociation rate. At high concentrations, they directly activate the opening of chloride channels and act on glutamate, adenosine, and neuronal nicotinic acetylcholine receptors.
- Barbiturates are metabolized primarily by hepatic oxidation. Their metabolism can be influenced by drugs that induce hepatic oxidative microsomes, such as barbiturates themselves.
- Barbiturates have various organ system effects:
- Central Nervous System (CNS): They cause proportional decreases in CMRO2 and CBF, reducing intracerebral pressure. They decrease mean arterial pressure less than ICP, improving cerebral perfusion. Maximum decrease in CMRO2 is around 50-55%, which requires hypothermia.
- Cardiovascular: Barbiturates induce peripheral vasodilation and decreased contractility, increasing heart rate and decreasing cardiac output.
- Respiratory: All intravenous induction agents except ketamine and etomidate cause dose-dependent respiratory depression, making respiratory parameters return to near normal within 15 minutes, with awakening occurring before normal respirations return.
- Barbiturates have been used in the past for neuroprotection during neurosurgery and following acute brain injuries. However, they have not been shown to be superior to other techniques for decreasing ICP following acute brain injury.
- Barbiturates were previously used for neuroprotection in procedures like carotid endarterectomy, temporary occlusion of cerebral arteries, profound induced hypotension, and cardiopulmonary bypass.
- Mechanisms of neuroprotective effect of barbiturates include reverse steal (Robin Hood) effect, free radical scavenging, and liposomal membrane stabilization. They can also block excitatory amino acids (EAA) at higher concentrations, functioning as anticonvulsants.
- Barbiturates have various contraindications: severe cardiovascular instability or shock, porphyria, and allergic reactions. Porphyria is a group of disorders with multiple subtypes, including acute intermittent porphyria, which is triggered by induction of heme synthesis.
- Barbiturate use has side effects and complications: cardiovascular and respiratory side effects are dose-dependent, and no significant differences exist between the barbiturates in terms of cardiovascular or respiratory side effects. At low blood levels, thiopental has been described as having an antianalgesic effect.
- Barbiturates have other uses: as a lethal injection combination, in truth serum, as a recreational drug, and as an intravenous induction agent.
- Thiopental, a commonly used barbiturate, has a high context sensitivity and may lead to accumulation of the active metabolite pentobarbital with multiple bolus dosing or prolonged infusion.
- Dosages for barbiturates vary for adults, children, and infants, and must be reduced in premedicated patients.
- Barbiturates can affect pregnancy, hypovolemia, obesity, females, and the elderly by decreasing the volume of the central compartment and the intermediate compartment.
- Thiopental infusions are used to treat status epilepticus and methohexital dosing is approximately 2 mg/kg.
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Test your knowledge of the mechanism of action and pharmacokinetics of a 25 mg repeated dose of GABAA agonist, including its effects on GABA, metabolism, and interactions with other drugs. This quiz covers the pharmacological aspects of this medication.
