Egar Video #11 Metabolism of Potent Inhaled Anesthetics

Question 1

True of False: All inhaled anesthetics are not metabolized.

Answer 1

False; they are ALL METABOLIZED.

Even nitrous oxide.

Question 2

How is nitrous oxide metabolized?

Answer 2

Intestinal bacteria mainly!!

*note: the liver may metabolize a small fraction

Question 3

True or false:

All inhaled anesthetics are metabolized at a different rate?

Answer 3

True

Note: older anesthetics (halothane, chloroform, methoxyflurane) are all metabolized

Over 3/4 of methoxyflurane was metabolized.

Question 4

Mechanism of how isoflurane are metabolized?

Answer 4

oxidation reaction

1. attacks C-O bond
2. created carbonyl bond (C double bond O)
3. hydrolysis to two groups (CO2 and HF) and TFA (trifluoroacetic acid)

*same for desflurane

Note: TFA is the immune response that would attack the liver of pts.

Question 5

Mechanism of how sevoflurane are metabolized?

Answer 5

1. insertion of active oxygen
2. splitting of sevo molecule
3. formation of hexofluranisopropanol
4. conjugation of glucuronaide and hexofluranisopropanol ( this make it inactive

hexofluranisopropanol - is a potent anesthetic. if it was not conjugated, properties of sevoflurane would change. this would cause a delay in recovery b/c it’s 1/2 life is many hours to days.

Question 6

How is glucurantion different in babies?

Answer 6

it is faster. so they have a faster recovery time compared to adults

Question 7

what does enzyme-induction mean?

Answer 7

you have increased production of certain enzymes that metabolize. these enzymes can be induced by drugs. (i.e phenobaritiol or ethanol) sometimes obesity.

Question 8

if patient has drugs that was enyzme induced what happenes?

Answer 8

Drug is more metabolized

urinary excretion in rats are increased after enzyme - induction for anesthetic like sevo.
it was almost unmeasurable for des after pretreatment with phenobaritol.