Etomidate Flashcards
Is etomidate a weak acid or base, and what is it’s pKa?
Weak base with a pKa of 4.2
What is the volume of distribution of etomidate?
2 - 4.5 L/kg
What is the clearance rate of etomidate?
18-25 ml/kg/min
What percentage of etomidate is protein bound?
75%
What is the elimination half-life of etomidate?
3 to 5 hours
What is the induction dose of etomidate?
0.2-0.6 mg/kg
A 65-year-old male with no past medical history undergoes a right total hip replacement. He undergoes induction of anaesthesia with etomidate, rocuronium and fentanyl and then receives maintenance anaesthesia with isoflurane. The patient exhibits seizure-like activity after induction.
Which of the following agents is most likely to cause this?
Etomidate
Rocuronium
Fentanyl
Isoflurane
Etomidate is known to prolong the duration of seizures.
A 25-year-old male is brought to A&E after a road traffic accident. He has sustained multiple injuries to face and chest. Due to haemodynamic instability and low GCS, he undergoes RSI with etomidate.
Which of the following is a well know side effect of this drug?
Hypotension
Hypertension
Bronchospasm
Adrenal Suppression
Etomidate is known to cause adrenal suppression via inhibition of the 11-beta hydroxylase enzyme.
Etomidate is known for its cardiovascular stability, and does not cause hypo- or hypertension. Furthermore, etomidate does not cause bronchospasm. It has minimal effect on ventilation and does not cause histamine release.
True or false regarding etomidate:
It is an imidazole derivative
True
True or false regarding etomidate:
It has two optical isomers
True
True or false regarding etomidate:
It has analgesic properties
False. Etomidate has no analgesic properties.
True or false regarding etomidate:
It does not cause thrombophlebitis
False. It causes thrombophlebitis on intravenous administration.
True or false regarding etomidate:
It acts on NMDA receptors
False. Etomidate is an imidazole derivative that acts on GABA receptors.
Regarding pharmacokinetics of etomidate (true or false):
It has poor lipid solubility
False. Etomidate is moderately lipid soluble, insoluble in water at physiologic pH, highly protein bound and metabolised in liver.
Regarding pharmacokinetics of etomidate (true or false):
It is soluble in water at normal pH
False. As a weak base, it will ionise (and therefore be more water soluble) at a pH below is pKa. It’s pKa is 4.2 and therefore it will be highly unionised at a pH of 7.4.
Regarding pharmacokinetics of etomidate (true or false):
It is highly protein bound
True
Regarding pharmacokinetics of etomidate (true or false):
The volume of distribution is doubled in patients with liver cirrhosis
True
Regarding pharmacodynamics of etomidate (true or false):
Increase heart rate on induction
True
Regarding pharmacodynamics of etomidate (true or false):
Reduces CBF, CMRO2 and ICP
True
Regarding pharmacodynamics of etomidate (true or false):
Obtunds pharyngeal and laryngeal reflexes
False. Etomidate maintains haemodynamics, laryngeal reflexes and reduces cerebral metabolism.
Regarding pharmacodynamics of etomidate (true or false):
Causes dose dependent reversible inhibition of 11β-hydroxylase
True
Regarding pharmacodynamics of etomidate (true or false):
Adrenocortical suppression is permanent
False. The adrenocortical suppression is temporary.
Regarding pharmacodynamics of etomidate (true or false):
The anaesthetic effect of R(+) etomidate is approximately five times that of S(−) etomidate.
True. The R(+) enantiomer of etomidate is significantly more potent as an anaesthetic compared to the S(−) enantiomer, with studies showing it to be approximately five times more effective.
Regarding uses of etomidate (true or false):
Induction agent for elderly patient with ischaemic heart disease
True
