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Clinically Based Concepts > module 3: points to ponder > Flashcards

module 3: points to ponder Flashcards

1
Q

what type of drugs is acetaminophen considered to be?

A

analgesic and antipyretic

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2
Q

what symptoms does acetaminophen reduce?

A

pain and fevers

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3
Q

which phase does acetaminophen undergoes?

A

II

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4
Q

what are the two pathways acetaminophen is metabolized after it undergoes phase II reaction?

A
  1. glucuronidated by glucuronosyltransferase
  2. sulfated by sulfotransferase
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5
Q

when acetaminophen undergoes phase II reactions, what does this allow for?

A

it can enter the plasma or bile

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6
Q

a small amount of acetaminophen undergoes phase I reaction by CYP450 to form what?

A

N-acetyl-p-benzoquinone imine (NAPQI)

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7
Q

what is NAPQI?

A

reactive oxygen species (free radical) that’s toxic to hepatocytes and is a strong oxidizer

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8
Q

what does it mean to oxidize something?

A

take an electron away

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9
Q

what antioxidant is present in high concentration in hepatocytes?

A

glutathione

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10
Q

what groups does NAPQI react with?

A

thiol

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11
Q

what enzyme adds glutathione to NAPQI to produce a harmless metabolite?

A

glutathione S- transferase

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12
Q

true or false: the typical amount of NAPQI produced after taking an appropriate dose of acetaminophen is easily neutralized by glutathione

A

true

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13
Q

what happens if you take too much acetaminophen?

A

Phase II reactions get overwhelmed leading to more Phase I reactions and a higher concentration of NAPQI in the liver.

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14
Q

what happens if enough NAPQI is formed to let glutathione be depleted?

A

it leaves NAPQI free to oxidize other compounds

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15
Q

how can NAPQI lead to hepatocellular necrosis and potentially liver failure?

A

by forming covalent bonds with sulfated molecules like cellular proteins

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16
Q

what is the cough suppressant that replaced codeine?

A

dextromethorphan

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17
Q

why can codeine and alcohol be dangerous?

A

codeine is an opioid and overdose can lead to respiratory depression, respiratory failure, and death

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18
Q

how is 70% of codeine converted to codeine-6-glucuronide?

A

hepatic enzyme UGT2B7

19
Q

what group does UGT2B7 transfer to codeine?

A

glucuronosyl

20
Q

what specific opioid receptor does codeine-6-glucuronide bind to?

A

mu

21
Q

what happens to the 30% of codeine that’s not glucuronidated?

A

about half is N-demethylated by CYP3A4 to form norcodeine and the other half results in the formation of morphine

22
Q

where does the oxidation occur when CYP3A4 demethylates codeine to form norcodeine?

A

during the demethylation process, enzymes oxidize N-methyl groups to remove them from the compound and norcodeine weakly binds to mu with similar weak physiological effects

23
Q

how does morphine form from the metabolism of codeine?

A

CYP2D6 uses an O-demethylation reaction that removes a methyl group from an oxygen atom

24
Q

what happens to the body when morphine is formed?

A

opioid that binds very well to mu in the brain and causes euphoria, pain relief, and respiratory depression

25
Q

what is the primary active ingredient in alcohol?

A

ethanol

26
Q

what is ethanol metabolized to once in the liver?

A

acetaldehyde

27
Q

the metabolism of ethanol involved what phase reaction and what enzyme?

A
  • phase I
  • alcohol dehydrogenase (non-cytochrome P450)
28
Q

what does alcohol dehydrogenase do?

A

removes H+ and e- from alcohol and pairs this with the reduction of NAD+ to NADH

29
Q

what is the end result of the oxidation of ethanol via alcohol dehydrogenase?

A

acetaldehyde

30
Q

what is CYP2E1?

A

located in smooth ER and works through microsomal oxidation when excessive amounts of alcohol (ethanol) is ingested

31
Q

describe microsomal oxidation with ethanol

A

ethanol is directly oxidized by molecular oxygen to acetaldehyde, so ethanol loses an electron to oxygen and reduces oxygen

32
Q

why can reduced oxygen be dangerous?

A

it becomes a free radical that damages protein and cell walls which then interferes with normal cellular function and viability

33
Q

when is CYP2E1 needed?

A

ONLY when alcohol dehydrogenase can’t keep up with alcohol consumption

34
Q

how is NADPH involved in microsomal oxidation?

A

gets oxidized to NADP+, losing an electron and H+ in the process

35
Q

what is acetaldehyde converted to by acetaldehyde dehydrogenase?

A

acetate

36
Q

what are the two reasons that the faster acetaldehyde is metabolized to acetate the better?

A
  1. acetaldehyde is a carcinogen
  2. it’s the reason you feel terrible after you’ve had too much to drink
37
Q

what is the major contributor to hangovers that causes headaches, tachycardia, flushing of skin from vasodilation, nausea, and vomiting?

A

acetaldehyde

38
Q

why kind of people are less likely to become alcholics?

A

people with increased alcohol dehydrogenase activity or decreased acetaldehyde dehydrogenase activity

39
Q

Many people from countries in _____ have an inactive version of acetaldehyde dehydrogenase-2 (ALDH2) in their liver.

A

Asia

40
Q

why is ALDH2 inactive?

A

due to a mutation that results in glutamate being replaced by lysine as the enzyme is synthesized

41
Q

the change in amino acids of ALDH2 _______ metabolism of acetaldehyde

A

slows

42
Q

what results from ALDH2 slowing the metabolism of acetaldehyde?

A

concentration of acetaldehyde in the blood increases drastically within a few minutes of consuming alcohol

43
Q

what drug is used to block active ALDH2 and why is it used to stop alcoholism?

A

Antabuse (disulfiram)
- causes inducible and dramatic increase in blood concentrations of acetaldehyde accompanied by serious hangover symptoms

Clinically Based Concepts (10 decks)

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