Elimination And Metabolism II Flashcards

1
Q

What is phase 1 reactions for

A

Increasing reactivity and polarity for excretion in kidney

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2
Q

What is phase 2 conjugate for

A

Increase polarity and water solubility

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3
Q

Explain aspirin metabolism

A

Aspirin to salicylate via aspirin esterase

Phase 2 adds a glucoronide / glucoronic acid for water solubility

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4
Q

What is phase 1 introduction called

A

Functionalisation

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5
Q

How do cytochrome p450 work in oxidation with the drug in phase 1

A

Bind to the drug to form a complex

Use NADPH reductase and NADPH and O2 to oxidate the drug to form water soluble product

Donate electrons

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6
Q

Most reactions occur via CYP, name and explain one which is independent and also occurs in liver

A

Alcohol dehydrogenase

Converts ethanol to acetal aldehyde via NAD reduction

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7
Q

Alcohol metabolism can also use which type of CYP to form acetal aldehyde from NADPH oxidation

A

CYP 2E1

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8
Q

Name 3 groups attached in phase II

A

Glucoronyl, sulphate, acetyl

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9
Q

Which enzyme is involved in glucoronidation eg of aspirin

A

UDP glucoronyl transferase

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10
Q

Which groups are added in penecillin phase 2 metabolism

A

Glucoronic acid and sulphate

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11
Q

Other than the glucoronidation of paracetamol and addition of sulphate , what other pathway is there which produces toxic product

A

CYP 2E1 which metabolised it to NAPQI (toxic)

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12
Q

Which enzyme detoxifies NAPQI from paracetamol metabolism

A

Glutathione s transferase

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13
Q

Why does overdose in paracetamol cause build up of NAPQI

A

Because too little glucoronyl and sulphate left to convert it

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14
Q

Name 3 internal factors affecting drug metabolism

A

Age
Genetics
Disease

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15
Q

Why does genetics affect drug metabolism

A

genetics will determine if someone has fast metabolism or slow metabolism

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16
Q

If someone has a fast metabolism, they have a normal therapeutic response and Cp level to the drug, what happens if someone has low rate

A

High Cp build up causing toxic effects

They have an excess therapeutic response to a small dose

17
Q

Why do both children and elderly have low metabolic rate

A

Low levels of cytochrome p450 and other conjugating enzymes such as udp glucoronyl transferase

Elderly also have dysfunctional liver etc

18
Q

Name some exogenous factors affecting metabolism and why they affect it

A

Drugs, smoking, alcohol

They either induce or inhibit metabolic enzymes

19
Q

Why does induction of metabolic enzymes mean someone needs to take more of the drug

A

Faster metabolic rate meaning lower therapeutic effect

20
Q

Why is ethanol toxic when taken with paracetamol

A

Induces CYP 2E1 which causes NAPQI production

21
Q

What does inhibition by factors such as drugs mean

A

Reduced rate of metabolism
(Lower effect of CYP or others)

Causes too high therapeutic response to a small dose

22
Q

Which exogenous factor is both an inducer and inhibitor

A

Ethanol / alcohol