Flashcards in Dexmedetomidine Deck (24)
What is the trade name for Dexmedetomidine?
What is the Formal drug classification of Dexmedetomidine?
-Highly selective specific and potent alpha 2 adrenergic agonist (1620:1 alpha2:alpha1)
-is the dextroisomer and pharmacologically active component of medetomidine
What are the clinical uses of Dexmedetomidine? (7)
-Provides dose-dependent sedation, analgesia, sympatholysis, and anxiolysis without significant respiratory depression; therefore may be a good agent to consider in pts with predicted difficult airways requiring sedation
-Sedation of non-intubated pts prior to and/or during surgical and other procedures
-Attenuates hemodynamic responses to tracheal intubation, decreases neuroendocrine responses during anesthesia and decreases requirements of co-administered anesthetics and analgesics
-Sedation of initially intubated and mechanically ventilated patients during treatment in an intensive care setting
-Prevention of drug withdrawal symptoms following long term sedation with benzos
-Prevention of shivering
-prevention of emergence delirium in pediatric patients
What is the MOA of Dexmedetomidine?
-Centrally and peripherally active alpha-2 adrenergic receptor agonist
-acts on alpha-2 receptors thereby producing sedation by decreasing SNS activity and the lvl of arousal
What MOA of CV effects does Dexmedetomidine have?
-regulates the CV system by inhibiting NE release
-Reduces BP and HR by decreasing the tonic levels of sympathetic outflow from the CNS and augmenting cardiac vagal activity
How is Dexmedetomidine metabolized?
-Undergoes extensive hepatic metabolism
-biotrasformation involves both direct glucuronidation as well as CYP450 mediated metabolism
-undergoes conjugation (41%), n-methylation (21%), or hydroxylation followed by conjugation
-has a weak inhibiting effect on CYP450 enzyme systems that might manifest as increased plasma concentration of opioids as administered during anesthesia
What does Dexmedetomidine have as an effect on CYP450? what might this manifest as?
weak inhibiting effect on CYP450 enzyme systems that might manifest as increased plasma concentration of opioids as administered during anesthesia
What is the elimination route of Dexmedetomidine?
undergoes almost complete biotransformation with very little excreted unchanged in the urine and feces
What is the volume of distribution of Dexmedetomidine?
Rapid distribution phase with a distribution 1/2 life of approximately 6 minutes; a terminal elimination 1/2 life of approximately 2 hours; and steady-state volume of distribution (Vss) of approximately 118 L (or 2 - 3 L/kg)
-Clearance is estimated to be approximately 39 L/hr (or 10 - 30 mL/kg/min
-context sensitive half-time ranges from 4 minutes after a 10 minute infusion to 250 minutes after an 8 hr infusion
Is dexmedetomidine protein bound?
the average normal protein binding is 94%
the fraction of precedex bound to plasma proteins is significantly decreased in subjects with hepatic impairment compared to healthy subjects
What are the side effects of Dexmedetomidine?
-hypotension and bradycardia may occur during administration and into the postop period
-Use beyond 24 hrs has been associated with tolerance and tachyphylaxis and a dose-related increase in adverse reactions
-transient htn has been observed primarily during the loading dose in association with the initial peripheral vasoconstrictive effects of Precedex.
What are the contraindications to the use of Dexmedetomidine?
use with caution in patients who may not tolerate decreases in SNS tone and resultant hypotension and bradycardia
What are the drug interactions associated with administration with Dexmedetomidine?
-Potentiates opioid analgesia and benzo induced hypnosis
-its pharmacodynamic effects are enhanced by Anesthetics, sedative, hypnotics, opioids. reduction in dosage of Precedex or the concomitant medication may be required
-Lowers Halothane MAC by nearly 100% through a specific post synaptic alpha-2 mechanism
-Attenuates delirium associated with Ketamine administration
What is the procedural sedation dose of Dexmedetomidine?
initiate at 1 mcg/kg over 10-15 minutes, followed by a maintenance infusion from 0.2 - 1 mcg/kg/hr
For patients over 65 yrs of age what should the loading dose of Dexmedetomidine be?
0.5 mcg/kg/min over 10 minutes
For patients with impaired hepatic function what should you consider with Dex?
a dose reduction should be considered
What is the dosage for treatment of pediatric emergence delirium associated with general anesthesia, for Dexmedetomidine?
give prophylactic dose of 1 mcg/kg approximately 30 minutes prior to emergence!
Of all the anesthetics, what does Dex most closely mimic physiologically?
-it produces sedation that most closely mimics physiological sleep:
-locus ceruleus (hypnosis)
-Spinal Cord (analgesia)
Is Dex water soluble or lipid soluble?
What are the CNS effects of Dex?
-Decreases CBF without changing ICP or CMRO2 significantly
-Decreases MAC of volatile agents and opioid requirements (up to 30%)
-Depresses thermoregulation (hypothermia, depresses shivering)
-Can build tolerance and dependence
What are the CV effects of Dex?
-Decreases HR, SVR, BP
-Bolus can cause transient increase in BP, and decrease in HR
-Potential for severe bradycardia, heart block, asystole
-Attenuates CV responses to noxious stimuli- decreases catecholamine levels during GA
What are the respiratory effects of Dex?
-minimal change in RR, moderate decrease in TV
-no change CO2 responsiveness
-upper airway obstruction
What is the E 1/2 t of Dex?