Etomidate

Question 1

Is etomidate a weak acid or base, and what is it’s pKa?

Answer 1

Weak base with a pKa of 4.2

Question 2

What is the volume of distribution of etomidate?

Answer 2

2 - 4.5 L/kg

Question 3

What is the clearance rate of etomidate?

Answer 3

18-25 ml/kg/min

Question 4

What percentage of etomidate is protein bound?

Answer 4

75%

Question 5

What is the elimination half-life of etomidate?

Answer 5

3 to 5 hours

Question 6

What is the induction dose of etomidate?

Answer 6

0.2-0.6 mg/kg

Question 7

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

Answer 7

Etomidate is known to prolong the duration of seizures.

Question 8

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

Answer 8

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.

Question 9

True or false regarding etomidate:

It is an imidazole derivative

Answer 9

True

Question 10

True or false regarding etomidate:

It has two optical isomers

Answer 10

True

Question 11

True or false regarding etomidate:

It has analgesic properties

Answer 11

False. Etomidate has no analgesic properties.

Question 12

True or false regarding etomidate:

It does not cause thrombophlebitis

Answer 12

False. It causes thrombophlebitis on intravenous administration.

Question 13

True or false regarding etomidate:

It acts on NMDA receptors

Answer 13

False. Etomidate is an imidazole derivative that acts on GABA receptors.

Question 14

Regarding pharmacokinetics of etomidate (true or false):

It has poor lipid solubility

Answer 14

False. Etomidate is moderately lipid soluble, insoluble in water at physiologic pH, highly protein bound and metabolised in liver.

Question 15

Regarding pharmacokinetics of etomidate (true or false):

It is soluble in water at normal pH

Answer 15

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.

Question 16

Regarding pharmacokinetics of etomidate (true or false):

It is highly protein bound

Answer 16

True

Question 17

Regarding pharmacokinetics of etomidate (true or false):

The volume of distribution is doubled in patients with liver cirrhosis

Answer 17

True

Question 18

Regarding pharmacodynamics of etomidate (true or false):

Increase heart rate on induction

Answer 18

True

Question 19

Regarding pharmacodynamics of etomidate (true or false):

Reduces CBF, CMRO2 and ICP

Answer 19

True

Question 20

Regarding pharmacodynamics of etomidate (true or false):

Obtunds pharyngeal and laryngeal reflexes

Answer 20

False. Etomidate maintains haemodynamics, laryngeal reflexes and reduces cerebral metabolism.

Question 21

Regarding pharmacodynamics of etomidate (true or false):

Causes dose dependent reversible inhibition of 11β-hydroxylase

Answer 21

True

Question 22

Regarding pharmacodynamics of etomidate (true or false):

Adrenocortical suppression is permanent

Answer 22

False. The adrenocortical suppression is temporary.

Question 23

Regarding pharmacodynamics of etomidate (true or false):

The anaesthetic effect of R(+) etomidate is approximately five times that of S(−) etomidate.

Answer 23

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.

Question 24

Regarding uses of etomidate (true or false):

Induction agent for elderly patient with ischaemic heart disease

Answer 24

True

Question 25

Regarding uses of etomidate (true or false):

Associated with myoclonus, grand mal seizures

Answer 25

True

Question 26

Regarding uses of etomidate (true or false):

Used for sedation in ICU

Answer 26

False. Etomidate is a stable induction agent for ischaemic heart disease. However, it is associated with myoclonus and seizures which limits its use as sedative in ICU.

Question 27

Regarding uses of etomidate (true or false):

Etomidate is known to be pophyrinogenic in animals

Answer 27

True