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Kinetics > E1 L5: Hepatic Drug Metabolism > Flashcards

E1 L5: Hepatic Drug Metabolism Flashcards

1
Q

Oxygen rich blood flows into the liver through the

A

Hepatic artery (20%)

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1
Q

blood flows out of the liver through

A

Hepatic veins

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2
Q

Nutrient rich blood coming from the bowel flows into the liver via

A

Portal vein (80%)

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3
Q

Bile composition

A

Water
Bile salts
Biirubin
Fats

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4
Q

Bile function

A

Surfactants
Helps fat digestion
Bilirubin elimination
Drug elimination

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5
Q

Portal triad

A

Hepatic vein, bile duct, and hepatic artery

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6
Q

Kupffer cell

A

Resident macrophage of the liver
Deal with bacteria

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7
Q

Bile flows from ____ and collects in the bile duct

A

Central vein

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8
Q

Lots of holes (fenestrae)
100-150nm (big holes)
Because of big holes - many molecules, including drugs, can leave the blood vessel and reach hepatocytes

A

Sinusoidal cells

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9
Q

Kupffer cell part of what system?

A

Reticuloendothelial system (RES)

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10
Q

Major cell of drug metabolism

A

Hepatocytes

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11
Q

70% of liver cells
Form Liver’s major metabolic and functional core (glucose metabolism, lipid metabolism)
Synthesis of plasma proteins such as albumin

A

Hepatocytes

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12
Q

Site where drug metabolizing enzymes are expressed and are responsible for drug metabolism

A

Hepatocyte
CYP450 - ER of hepatocyte
UGT - ER of hepatocyte

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13
Q

Principles of drug metabolism: Converts _____ chemicals into _____ which are readily excreted in urine or bile

A

Lipophilic -> hydrophilic

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14
Q

Certain compounds have ___ _____ effect, meaning they cannot be metabolized

A

First past

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15
Q

When a drug can be metabolized:

A

Chemical structure is modified
Goes under phase II reaction
eliminated into urine
Pumped into blood side

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16
Q

What two types of elimination makes up 90% of elimination

A

Hepatic metabolism and renal
(the rest are drugs that do not make it through eliminated in bile)

17
Q

T/F: You do not always have to do phase I followed directly by phase II

A

True
-If chemical already has hydroxy, can go directly into phase II

18
Q

4 major pathways of metabolism

A

Oxidation
UDP glucuronosyl transferase (UGT)
Hydrolysis
Reduction

19
Q

What are the most common pathways of drug metabolism

A

Oxidation and conjugation

20
Q

Hydrolysis mech

A

Ester group; add water, bond is cleaved and becomes carboxylic acid and alcohol
(Enzyme: Carboxyesterase)

20
Q

Oxidation mech

A

Hydroxyl
Typically mediated by CYP450

20
Q

Conjugation mech

A

Attach hydrophilic group to chemical
Usually mediated by UGT

21
Q

Reduction mech

A

Undergoes reduction (keto group becomes alcohol)
Major enzyme: Carbonyl reductase

22
Q

Where do metabolism pathways occur?

A

Liver

23
Q

Two major enzyme classes in metabolism

A

CYP450 and UGT

24
Q

Ranks 1st in catalytic versatility and the # of drugs it detoxifies among different enzymes
Highest level of drug metabolizing - is found in the liver (ER) among different tissues

A

Cyp450

25
Q

Mono oxygenase

A

Less than 10 enzymes are responsible for drug metabolism

26
Q

Reactions mediated by P450

A

Aromatic hydroxylation
Aliphatic hydroxylation
N-dealkylation
O-dealkylation

27
Q

Cyp450 phenotyping

A

Add drug to different tubes - see which drug exhibits the best enzyme activity

28
Q

Enzyme inducing drug:

A

Rifampin
Activates transcription factor PXR/ leading decreased exposure to enzyme substrates

29
Q

Enzyme inhibiting drug

A

Ketoconazole
-Leads to increased substrate drug exposure

30
Q

A collective term for microorganisms in human gut

A

Gut microbiota

31
Q

The gut microbiota mediates certain drug metabolism, mainly -

A

Reduction and hydrolysis

32
Q

Outnumber human cells by 3x
Involved in various biological functions, e.g. digestion of fiber

A

Gut microbiota

33
Q

Double peak phenomenon is caused by

A

Enterohepatic cycling

34
Q

Q: T/F: Kupffer cells are the primary cells in the liver responsible for drug metabolism

A

False - hepatocytes

35
Q

Q: Choose two main (most common) drug metabolism reactions in the liver
Oxidation
Reduction
Hydrolysis
Conjugation

A

Oxidation - mediated by P450
conjugation - mediated by UGT

36
Q

Q: T/F: Among CYP450 enzymes, CYP3A4 metabolizes the largest fraction of drugs

A

True

37
Q

Q: T/F: The portal triad comprises the bile duct, portal vein, and central vein

A

False - bile duct, portal vein, hepatic artery

38
Q

Q: T/F: Enzyme inducers of CYP3A4 would likely decrease the systemic exposure of CYP3A4 substrate

A

True (rifampin)

39
Q

Q: T/F: Enzyme inhibitors of CYP3A4 would likely increase the systemic exposure of CYP3A4 substrate

A

True

Kinetics (20 decks)

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