Dexmedetomidine Flashcards
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Questions and Answers

What is the mechanism of action (MOA) of Precedex?

Potent alpha2 agonist (CNS & PNS)

What type of sedative hypnotic is Precedex?

  • Barbiturate
  • GABA
  • NONGABA (correct)
  • Opioid

    • What causes the hypnotic effect of Precedex?

    Presynaptic alpha 2 receptor stimulation in CNS inhibits locus coeruleus in the pons.

    Precedex is ________ times more selective for alpha 2 and ___________ times more selective than clonidine for alpha 2.

    <p>~1600X more selective for alpha 2; ~8X more selective than clonidine for alpha 2.</p> Signup and view all the answers

    What pathways does Precedex activate to produce sedation?

    <p>Dec SNS activity.</p> Signup and view all the answers

    At what level does the analgesic effect of Precedex occur?

    <p>Spinal cord.</p> Signup and view all the answers

    Which of the following are presynaptic alpha 2 receptor actions? (Select all that apply)

    <p>Inhibit NE release</p> Signup and view all the answers

    What are the postsynaptic alpha 2 receptor actions? (Select all that apply)

    <p>Decrease SNS</p> Signup and view all the answers

    What are the clinical uses of Precedex? (Select all that apply)

    <p>Sedation</p> Signup and view all the answers

    Precedex is highly __________ soluble & ____________% protein bound.

    <p>Lipid soluble; 90% protein bound.</p> Signup and view all the answers

    How is Precedex metabolized?

    <p>Liver P450 enzymes.</p> Signup and view all the answers

    Where is Precedex excreted?

    <p>Kidneys &amp; GI tract.</p> Signup and view all the answers

    Does Precedex have an active metabolite?

    <p>False</p> Signup and view all the answers

    What is the elimination half-time of Precedex?

    <p>2-3 hours.</p> Signup and view all the answers

    What is the loading and maintenance dosing for Precedex?

    <p>Loading = 0.5-1 mcg/kg over 10-15 min; Maintenance = 0.3-0.7 mcg/kg/hr infusion.</p> Signup and view all the answers

    What is the onset time of Precedex after a loading dose?

    <p>10-20 min.</p> Signup and view all the answers

    Precedex produces a ________ dependent DEC in CBF.

    <p>Dose.</p> Signup and view all the answers

    Does Precedex affect CMRO2 or ICP?

    <p>False</p> Signup and view all the answers

    What type of sleep does Precedex sedation mimic?

    <p>Natural sleep.</p> Signup and view all the answers

    Does Precedex provide reliable amnesia?

    <p>False</p> Signup and view all the answers

    Does Precedex impair evoked potentials during neuromonitoring?

    <p>False</p> Signup and view all the answers

    Precedex can be useful for '______ ______' testing during neuro procedures.

    <p>'Wake up.'</p> Signup and view all the answers

    What are the most common cardiovascular side effects associated with Precedex? (Select all that apply)

    <p>Bradycardia</p> Signup and view all the answers

    DEC HR & BP seen from DEC SNS result from ______________ alpha 2 stimulation.

    <p>Peripheral.</p> Signup and view all the answers

    DEC SNS also results in DEC myocardial ________ & ___________.

    <p>Contractility &amp; ischemia.</p> Signup and view all the answers

    What effect can rapid IV bolus administration of Precedex have?

    <p>Transient increase in BP.</p> Signup and view all the answers

    What respiratory effect of Precedex is advantageous for 'difficult airway' management?

    <p>Preserved breathing without respiratory depression.</p> Signup and view all the answers

    Precedex produces an antishivering effect by ___________ the thermoregulatory response.

    <p>Impairing.</p> Signup and view all the answers

    Precedex (INC/DEC) incidence of ED in pedi.

    <p>Decreases.</p> Signup and view all the answers

    Analgesia is produced by ________ -# stimulation in the _________ ________ of the SC by DEC substance P & glutamate release.

    <p>ALPHA2; DORSAL HORN.</p> Signup and view all the answers

    Study Notes

    Dexmedetomidine (Precedex) Overview

    • Potent alpha2 agonist affecting both CNS and PNS.
    • Classified as a non-GABA, non-barbiturate sedative-hypnotic.

    Mechanism of Action

    • Hypnotic effects arise from presynaptic alpha2 receptor stimulation in the CNS, inhibiting the locus coeruleus, linked to wakefulness and vigilance.
    • Approximately 1600 times more selective for alpha2 receptors than other agents and eight times more selective than clonidine.
    • Activates pathways that reduce sympathetic nervous system (SNS) activity, allowing for easy arousal from sedation.
    • Analgesic effects manifest at the spinal cord level.

    Receptor Actions

    • Presynaptic alpha2 actions:
      • Inhibits norepinephrine (NE) release.
      • Produces sedation and decreases minimum alveolar concentration (MAC).
    • Postsynaptic alpha2 actions:
      • Decreases sympathetic nervous system (SNS) tone, blood pressure (BP), and heart rate (HR).
      • Reduces opioid requirements for analgesia.

    Clinical Uses

    • Effective for sedation during awake fiberoptic intubations.
    • Acts as an adjunct to general anesthesia, sparing anesthetic (up to 90% decrease in MAC).
    • Provides analgesia and aids in withdrawal from alcohol, opioids, and cocaine.
    • Useful for anxiolysis in preoperative pediatric cases, and prolonging motor/sensory blocks with local anesthetics.

    Pharmacokinetics

    • Highly lipid-soluble; 90% protein-bound.
    • Metabolized in the liver through cytochrome P450 enzymes with both Phase I (methylation, hydroxylation) and Phase II (conjugation) processes.
    • Excreted via kidneys and gastrointestinal tract, with no known active metabolites.
    • Short elimination half-time of 2 to 3 hours.

    Dosing Information

    • Loading dose of 0.5-1 mcg/kg administered over 10-15 minutes; maintenance infusion of 0.3-0.7 mcg/kg/hr.
    • Onset of action occurs within 10-20 minutes post-loading, with a duration of 10-30 minutes after stopping the infusion.

    Effects on Cerebral Hemodynamics

    • Dose-dependent reduction in cerebral blood flow (CBF) with no change in cerebral metabolic rate of oxygen consumption (CMRO2) or intracranial pressure (ICP), indicating an uncoupling between CBF and CMRO2.
    • Sedation mimics natural sleep patterns.

    Memory and Neuromonitoring

    • Amnesia is not reliably produced; may not impair evoked potentials during neuromonitoring.
    • Useful for "wake-up" testing during neuro procedures.

    Cardiovascular and Respiratory Effects

    • Common cardiovascular side effects include bradycardia and hypotension resulting from peripheral alpha2 stimulation and reduced SNS tone.
    • Rapid IV bolus can initially increase BP due to vasoconstriction before the central response takes over.
    • Maintains respiratory function with minimal reduction in ventilation and absence of respiratory depression, beneficial for managing difficult airways.

    Antishivering and Pediatric Considerations

    • Impairs the thermoregulatory response to produce an antishivering effect.
    • Reduces the incidence of emergence delirium (ED) in pediatric patients.

    Analgesia Mechanism

    • Analgesic efficacy is linked to alpha2 stimulation in the dorsal horn of the spinal cord, decreasing the release of substance P and glutamate.

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    Description

    Test your knowledge about Dexmedetomidine, known as Precedex, with these flashcards. Covering its mechanism of action, classification as a sedative hypnotic, and its effects on the central nervous system, this quiz is perfect for students and professionals in the medical field.

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