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Drug Action > Chemical Pathways of Drug Metabolism Phase I and II > Flashcards

Chemical Pathways of Drug Metabolism Phase I and II Flashcards

1
Q

What type of metabolism occurs before the drug reaches systemic circulation?

A

Pre-systemic metabolism

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2
Q

What is the most commonly seen metabolizing enzyme in the blood?

A

Esterases

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3
Q

What are the two major classifications of drug metabolism?

A

Hepatic and extra-hepatic

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4
Q

What are the two common sites of pre-systemic metabolism?

A

GI tract and liver

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5
Q

Which CYP enzyme is the major one found in the GI?

A

CYP3A4

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6
Q

Which CYP enzymes are polymorphic?

A

All to a certain degree

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7
Q

Where can esterases be found?

A

Blood, liver, GI tract

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8
Q

Which phase II enzymes are polymorphic?

A

UGTs largely, TPMT, NAT1, NAT2, GSTs (M,T,P,A)

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9
Q

Where is enzyme CYP2E1 most commonly expressed?

A

Lungs

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10
Q

Major con of CYP2E1?

A

Metabolizes procarcinogens in the body

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11
Q

What factor largely affects how much of an enzyme each individual expresses?

A

Genetic factors

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12
Q

Which enzyme shows increased activity due to inflammation?

A

CYP2E1

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13
Q

Which 2 CYP enzymes are commonly affected by a deleted gene mutation?

A

CYP2D6 and CYP2C19

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14
Q

The expression of which 5 CYP enzymes can be either be increased or decreased by polymorphism?

A

CYP2D6, CYP2C19, CYP2C8, CYP2B6 and CYP2A6

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15
Q

What is the main purpose of metabolism?

A

Make the drug more water solubility, making excretion possible

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16
Q

What is the primary method of excretion for Phase I metabolic waste?

A

Urine

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17
Q

What is the primary method of excretion for Phase II metabolic waste?

A

Feces

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18
Q

True or false: Non-polar conjugates are commonly excreted in the urine

A

False. Non-polar conjugates are commonly excreted in the feces, and polar metabolites in the urine

19
Q

In what case may a drug directly undergo Phase II metabolism?

A

The drug already contains a functional group (biological marker) identifying it should undergo Phase II metabolism

20
Q

Exceptions to the Phase II metabolism rule

A

Methylation and acetylation. Decrease water solubility

21
Q

What is the major Phase I reaction?

A

Oxidation

22
Q 
Which of the following is not a Phase I reaction?
.Oxidation
.Methylation
.Hydrolysis
.Reduction
A

Methylation

23
Q

What non-CYP enzyme is highly responsible for oxidation reactions?

A

Monoamine oxidase (MAO)

24
Q

What is the most common Phase II reaction?

A

Glucuronidation

25
Q

True or false: 95% of oxidation reactions are catalyzed by CYP enzymes

A

True

26
Q

Which enzyme converts codeine to morphine?

A

CYP2D6

27
Q

True or false: If morphine is administered, it will undergo Phase I metabolism

A

False. Morphine undergoes Phase II metabolism. If codeine is administered, it undergoes Phase I metabolism and is converted to morphine

28
Q

True or false: Deamination of a terminal amine forms a ketone

A

False. It forms a carboxylic acid

29
Q

True or false: Deamination of a penultimate amine forms a ketone

A

True

30
Q

True or false: Formation of both ketones and carboxylic acids after metabolism will increase water solubility

A

False. Formation of ketones decreases water solubility

31
Q

What are the 3 Phase I reactions from most to least occurence?

A

Oxidation, hydrolysis, reduction

32
Q

Which two enzymes are highly responsible for hydrolysis?

A

Esterases and amidases

33
Q

True or false: Amidases and esterases are both highly suited for drug metabolism

A

False. Amidases are mostly suited for protein and peptide metabolism

34
Q

Glucuronidation at the carboxylic acid group, or _____________, is the least common form of glucuronidation

A

Acylglucuronidation

35
Q

True or false: GSSG is the active form of glutathione because it has a free thiol group

A

False. GSH is the active form

36
Q

True or false: Glutathione undergoes conjugation in the presence of enzymes or nucleophiles (electron donating groups)

A

True

37
Q

What is the most commonly seen type of amino acid conjugation?

A

Glycine conjugation

38
Q

Glycine conjugation is the major metabolic route for xenobiotic ________ _______

A

Carboxylic acids

39
Q

Why should newborns not receive anything containing benzoic acid preservatives?

A

Their glycine conjugation pathway is underdeveloped, therefore, preparations containing preservatives can lead to toxicity

40
Q

Why are methylation and acetylation considered Phase II reactions?

A

These processes add on functional groups (conjugate), despite decreasing water solubility

41
Q 
Imipramine can undergo all metabolic transformations except:
Oxidative Deamination
Oxidative N-Dealkylation
Hydrolysis
Aromatic Oxidation
Glucuronide conjugation
A

Hydrolysis

42
Q 
Which of the following structural features must be present in an organic compound for it to undergo amino acid conjugation? 
Amines
Alcohols
Epoxides
Esters
Carboxylic acids
A

Carboxylic acids

43
Q

Highly lipophilic amine containing compounds undergo N-dealkylation at an (inc/dec) rate

A

Increased

Drug Action (17 decks)

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