Flashcards in Etomidate Deck (34)
What is the trade name for Etomidate?
What is the formal drug classification for Etomidate?
-IV general anesthetic
-ultra short acting non-barbiturate hypnotic
-The structure of Etomidate is a carboxylated imidazole
What are the clinical uses for Etomidate? (5)
-used for induction and maintenance of anesthesia
-useful in hemodynamically unstable patients and those with poor CV function (pts with baseline low EF or pts with severe hypovolemia)
-may be preferable to Thiopental (and propofol) in patients at risk of circulatory failure
-NO analgesic properties
-may be used in hemodynamically unstable pts with intracranial pathology as it decreases CBF, Cerebral metabolism and ICP with minimal impact on CPP compared to other IV anesthetics
What is the MOA of Etomidate?
-Augments the inhibitory tone of GABA in the CNS by binding to the GABAa receptor and increasing the affinity of GABA for the receptor; this subsequently increases chloride conductance and hyperpolarizes the POST-synaptic cell membrane producing hypnosis
-produces rapid induction of anesthesia with minimal CV effects
Does Etomidate produce analgesia?
What receptor does Etomidate act on?
How is Etomidate metabolized?
-Clearance is by the liver 18 - 25 ml/kg/min, with hepatic extraction ratio of -.5 +/- 0.9
-Ethyl ester side chain is rapidly metabolized by hydrolysis via hepatic microsomal emzymes and plasma esterases to its carboxylic acid ester, which results in a water soluble, pharmacologically inactive compound
-Liver, ester hydrolysis or N-dealkylation to caroxylic acid
-Biotransformation 5x faster than TPL
What are the CardioPulmonary Bypass considerations of Etomidate?
Hypothermic bypass causes an initial decrease of ~34% of plasma etomidate concentration that will return to ~11% of the pre-bypass value, which is then followed by increased metabolism on rewarming
-hepatic blood flow decreases during bypass may be important due to the high liver extraction of etomidate
How is Etomidate redistributed?
-Effects of a bolus dose are terminated by redistribution
-Penetrates brain within 1 minute of IV administration
What is the elimination route of Etomidate?
Clearance 10 -20 mL/kg/min; 85% renal, 13% Biliary excretion; 2% unchanged
What is the volume of distribution of Etomidate?
Distribution 1/2 life - 2.7 min; Redisribution 1/2 life 29 min
What is the E 1/2 life of Etomidate?
2.9 - 5.3 hours (3 - 5 hours)
How is Vd of Etomidate changed in patients with cirrhosis?
Vd and E 1/2 life is doubled, clearance is normal
What does a large Vd suggest of Etomidate?
considerable tissue uptake
Is Etomidate protein bound?
75% protein bound
What are the side effects of Etomidate? (6)
-Myoclonus due to subcortical disinhibition
-Venous irritation and superficial thrombophlebitis
-Unwanted excitatory effects during induction and recovery
Explain the side effect of Etomidate causing Adrenal Suppression.
-A single dose suppresses adrenal steroid synthesis for up to 24 hours!!
-Etomidate inhibits 11-B-Hydroxylase, an enzyme important in adrenal steroid production; also inhibits 17-alpha-hydroxylase
-prevents conversion from cholesterol to cortisol
-this has been associated with increased mortality in severly ill patients, therefore should not be used in patients with adrenal insufficiency
What are the CV side effects of Etomidate?
-Minimal CV change due to lack of effect on SNS and baroreceptors; no change in BP to decreased, no change in HR
What are the respiratory side effects of Etomidate?
Dose dependent, decreased resp rate and tidal volume, transient apnea may occur
-Ventilatory response to CO2 depressed minimally
-hiccups or coughing
What pregnancy category is Etomidate?
What are contraindications to administration of Etomidate?
-Hypersensitivity to Etomidate or any component of the formulation
-Pediatric use not recommended
-Small doses of Etomidate may elicit seizure activity in patients with an underlying seizure disorder
What are the drug interactions with Etomidate?
No known drug interactions
What is the induction of GA dose for Etomidate?
0.2 - 0.6 mg/kg IV (***0.3mg/kg) over 20-60 seconds ***because of this drugs side effects profile, rarely would give it over this dose therefore learn 0.2 - 0.3 mg/kg as induction dose
What is the maintenance dose for Etomidate?
5 - 20 mcg/kg/min IV; 10 mcg/kg/min with N2O and an opiate
When does Etomidate lose CV protective effects?
when the induction dosing is increased over 0.2 - 0.3 mg/kg!! because of this drugs side effects profile, rarely would give it over this dose therefore learn 0.2 - 0.3 mg/kg as induction dose
What should you consider with Etomidate administration in patients undergoing severe stress?
What is Etomidate a derivative of ?
Carboxylated Imidazole derivative
How is Etomidate prepared?
-Propylene glycol solvent
-pH 6.9 so it is water soluble in soln?
-At physiologic pH, becomes HIGHLY lipid soluble
What is important to consider regarding Hepatic clearance of Etomidate?
-High hepatic extraction ratio and clearance: changes in liver blood flow or function will prolong effects