Etomidate
chemical properties
carboxylated imidazole compound
water-soluble at an acidic pH
lipid soluble at physiologic pH
*35 % propylene glycol causing pain on injection and venous irritation
onset
1 min s/p IVP
myoclonus
50-80%
alteration in the balance of inhibitory and excitatory influences on the thalamocortical tract
*can be attenuated by prior administration of opioids or benzos (fentanyl 1-2 mcg/kg IV)
CV
CV stable minimal changes in HR, SV, CO, contractility
mild decrease in MAP d/t decreased SVR
MOA
selective modulator of GABA A receptors
protein binding
76% albumin
Cautions of Etomidate Administration
pt with seizure hx
hemorrhage or sepsis
hypotension with etomidate
sudden hypotension with hypovolemia
Especially at high doses 0.45 mg/kg IV
oral bioavalibility
direct systemic absorption in oral mucosa that bypasses hepatic metabolism
Vd
clearance
vd= 2.2 -4.5 L/kg
clearance = 10-20 mL/kg/min
adrenocortical suppression
dose-dependent inhibition of conversion of cholesterol to cortisol
* no stress response
*severe HypoTN, longer MV hours
*enzyme inhibition lasts 4-8hrs
intra-arterial damage
histamine release
no and no :)
dose
0.3 mg/kg IV
metabolism
hydrolysis by hepatic microsomal enzymes and plasma esterase
CNS effects
decrease CBF and CRMO2 by 35-45%
* potent, direct cerebral vasoconstrictor
* decreases ICP
ventilation
rapid injection -> apnea
VT decreases are offset by compensatory increases in frequency of breathing (transient 3-5 minutes)
stimulates CO2 medullary centers
uses
unstable CV system
*especially with little or no cardiac reserve
elimination
85% in urine & 10-13% in bile
E 1/2 = 2-5 hrs
EEG effects
excitatory spikes
may activate seizure foci
*may augment the amplitude of SSEP.. more labile monitoring
enzyme inhibited by etomidate
11-beta-hydoxylase