Pharm 5 - Drug Metabolism Flashcards Preview

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Flashcards in Pharm 5 - Drug Metabolism Deck (25)
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1
Q

What is the purpose of metabolism?

A

Converts lipophilic into polar derivates (polar derivates are readily excreted)

2
Q

Why should systemic-effect medicines have a low hepatic first pass?

A

Ensures most of the drug isn’t metabolised so there is enough to get inside the organ and produce desired effect

3
Q

What 3 reactions occur in phase 1 metabolism?

A

Oxidation / reduction / hydrolysis

4
Q

What main reactions occur in phase 2 metabolism?

A

Glucuronidation / acetylation / amino acid conjugation / methylation / sulphating / glutathione conjugation

5
Q

What does phase 2 metabolism do?

A

Makes drug water soluble by adding a polar group

6
Q

How is the Polarity of the drug affected after phase 1 metabolism?

A

Little change in polarity

7
Q

What else may phase 1 metabolism do?

A

Activate / inactivate chemicals

8
Q

Where is the point of attachment for phase 2 metabolism?

A

Functional groups

9
Q

How does oxidation and reduction and hydrolysis affect functional groups?

A

Oxidation / reduction = creates new functional groups

Hydrolysis exposes the functional groups

10
Q

Where is the cytochrome p450 enzyme system mainly found?

A

Liver endoplasmic reticulum

11
Q

What metabolic process is cytochrome p450 involved in?

A

Phase 1 oxidation reactions

12
Q

In oxidation by p450, what is the rate limiting step?

A

2nd reduction (step after stable Fe3+ forms)

13
Q

What does glutathione consist of?

A

Cysteine / glycine / glutamate

14
Q

What does flavin containing monooxygenase do?

A

Converts trimethylamine to amine oxide

15
Q

When does hydrolysis occur?

A

Whenever there is an ester or amide

16
Q

Does p450 use NADPH or NADH more commonly as a cofactor?

A

NADPH

17
Q

Conjugation in phase 2 reactions typically leads to an inactive conjugate. Name an exception

A

Morphine

18
Q

What do phase 2 reactions achieve?

A

Makes conjugate less lipid soluble = easier to excrete

19
Q

What defence reaction does phase 2 metabolism do against pathogens and toxins?

A

Glutathione conjugation

20
Q

Which phase 2 reaction occurs most often?

A

Glucuronidation

21
Q

Which cofactor does glucuronidation use?

A

UDGPA

22
Q

Which 3 elements can be acetylated in phase 2 metabolism?

A

N / O / S

23
Q

Which compound acts as the donor in methylation?

A

S-adenosyl methionine

24
Q

In paracetamol, which reaction happens first?

A

Phase 2 reactions

25
Q

What is the cofactor for oxidation?

A

Either CYP2E1 or CYP3A4

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