68 Questions
Propofol can be slowly released from a peripheral compartment, which does not interfere with awakening from a bolus dose or infusion.
True
Propofol dosing for unconsciousness is at 2-6 μg/ml.
True
Morbidly obese patients should be dosed based on their total body weight.
False
Elderly patients require a 25-50% increase in propofol dose.
False
Propofol has a context-sensitive half-time due to its rapid effect-site equilibration.
True
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.
False
Propofol has an antiemetic effect and can be used to reduce postoperative nausea and vomiting in PACU.
True
Propofol has an antipruritic effect and is effective in treating neuraxial opioid-associated pruritis.
True
Propofol has anticonvulsant activity and can terminate generalized seizure activity.
True
Propofol can attenuate bronchoconstriction and is appropriate for use in asthmatic patients.
True
Propofol has analgesic effects and is beneficial in acute nociceptive pain.
False
Propofol has been shown to reduce cerebral blood flow and intracranial pressure.
True
Etomidate can benefit patients with elevated intracranial pressure (ICP)
True
Etomidate reduces cerebral blood flow by up to 35%
True
Etomidate inhibits cortisol and mineralocorticoid production for up to 72 hours after a single induction dose
True
Etomidate derivatives, such as methoxycarbonyletomidate and carboetomidate, have similar structures and pharmacological properties compared to etomidate
False
Etomidate has a high incidence of postoperative nausea and vomiting (PONV) when given with narcotics
True
Etomidate acts as a negative allosteric modulator of the γ-aminobutyric acid-A (GABA) receptor
False
Etomidate has a similar volume of distribution to other benzodiazepines
True
Etomidate has neuroprotective activity, which is well-documented in humans
False
Etomidate can cause apnea in large doses
True
Flumazenil acts as a competitive antagonist, preventing or reversing the effects of other benzodiazepines in a dose-dependent manner
True
Flumazenil is used for reversing residual benzodiazepine-induced sedation
True
Flumazenil has a slow clearance rate
False
Barbiturates directly activate the opening of chloride channels at low concentrations
False
Barbiturates induce peripheral vasoconstriction
False
Barbiturates have been shown to be superior to other techniques for decreasing ICP following acute brain injury
False
Barbiturates were previously used for neuroprotection in procedures like carotid endarterectomy
True
Barbiturates can function as anticonvulsants at higher concentrations
True
Barbiturates are contraindicated in severe cardiovascular instability or shock
True
Thiopental has been described as having an antianalgesic effect at low blood levels
True
Barbiturates are commonly used as a recreational drug
True
Thiopental infusions are used to treat status epilepticus
True
Barbiturates dosages must be increased in premedicated patients
False
Barbiturates can affect pregnancy by increasing the volume of the central compartment
False
Methohexital dosing for status epilepticus is approximately 2 mg/kg
True
Ketamine has been used in low doses to induce seizure discharges in temporal lobe epilepsy.
True
The S(+) isomer of ketamine has 4x greater affinity for the phencyclidine binding site on the NMDA receptor than the R(-) isomer.
True
Ketamine has analgesic effects due to its strong binding to mu opioid receptors.
False
R(-) ketamine is available in Europe but not in the United States.
False
Ketamine produces a dissociative state resulting in intense analgesia and amnesia.
True
Ketamine binds with multiple CNS receptors, including NMDA, opioid, and muscarinic receptors.
True
Ketamine's rapid onset of action is due to its low lipid solubility.
False
The major pathway for ketamine metabolism leads to the active metabolite norketamine.
True
Ketamine has a long duration of action due to its extensive protein binding.
False
Ketamine can speed delivery of the drug to the brain through increased cerebral blood flow.
True
Propofol is insoluble in aqueous solution.
True
Propofol is excreted by the liver.
False
Propofol is provided in an emulsion containing 1% propofol, 10% soybean oil, 2.25% glycerol, and 1.2% purified egg phosphatide.
True
Propofol has a context-sensitive half-time of less than 40 minutes for infusions up to 8 hours duration.
True
Propofol has anticonvulsant activity and can terminate generalized seizure activity.
False
Propofol clearance exceeds hepatic blood flow.
True
Propofol has been shown to reduce cerebral blood flow and intracranial pressure.
True
Propofol has analgesic effects and is beneficial in acute nociceptive pain.
False
Propofol has an antiemetic effect and can be used to reduce postoperative nausea and vomiting in PACU.
True
Propofol dosing for unconsciousness is at 2-6 μg/ml.
False
Midazolam undergoes first-pass metabolism before reaching systemic circulation
True
The primary metabolite of midazolam is 1-hydroxymidazolam, which has approximately 50% activity of the parent compound
True
Midazolam clearance is 10 times greater than that of diazepam and 5 times greater than that of lorazepam
True
Midazolam is typically used for preoperative anxiolysis and sedation, with a slower onset than thiopental or propofol, but reliable amnesia
True
Lorazepam has a lower lipid solubility, resulting in a delayed onset of effect in the CNS
True
Lorazepam has a higher affinity for GABA receptors compared to diazepam, resulting in longer-lasting effects despite higher clearance and similar volume of distribution
True
Lorazepam has been shown to reduce cerebral blood flow and intracranial pressure
False
Lorazepam is metabolized via hepatic glucuronidation to inactive metabolites, relatively unaffected by inhibition of cytochrome P-450 or changes in hepatic function
True
Midazolam is insoluble in water and is dissolved in organic solvents such as propylene glycol and sodium benzoate
True
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
True
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
True
Lorazepam has been described as having an antiemetic effect and can be used to reduce postoperative nausea and vomiting in PACU
False
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.
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.
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