Drug Metabolism Flashcards Preview

► Med - Pharmacology > Drug Metabolism > Flashcards

Flashcards in Drug Metabolism Deck (20)
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1
Q

What is the function of inactivation?

A

Facilitate elimination - inactive metabolite is more easily eliminated. Lipid-soluble (hydrophobic) drugs converted to water soluble (hydrophilic) metabolite.

2
Q

Where does drug metabolism primarily occur?

A

Liver

3
Q

Where does drug elimination primarily occur?

A

Kidney

4
Q

Where are Phase I enzymes found?

A

Mainly endoplasmic reticulum

5
Q

Where are Phase II enzymes found?

A

Mainly cytoplasm

6
Q

What occurs during Phase I?

A

Drugs are made more hydrophilic and the addition of functional groups

7
Q

What occurs during Phase II?

A

Conjugation with endogenous substances occurs onto the functional group

8
Q

What is the main system that mediates Phase I reactions?

A

Mixed Function Oxidase System (MFO)

9
Q

What are the 4 main elements of the MFO?

A
  • Cytochrome P450 Hemoprotein
  • NADPH Cytochrome P450 Reductase
  • NADPH
  • O2
10
Q

What is the fate of O2 during the MFO reactions?

A

One O atom is placed onto the drug and one O atom is turned into H2O.

11
Q

What does non-microsomal oxidation occur on?

A

Alcohol

12
Q

What is the function of conjugations in Phase II?

A

Create a highly polar conjugate to excrete

13
Q

First-pass effect

A

Many orally administered drugs will be extensively biotransformed before they reach the systemic circulation due to biotransformation in the G.I. tract and liver

14
Q

What is the net equation of the Phase I reaction?

A

RH + O2 + NADPH + H+ -> ROH + H2O + NADP+

15
Q

What is PABA structurally similar to?

A

Sulfonamides

16
Q

What are some drug-age interactions in neonates and the elderly?

A

Slow biotransformation in neonates and elderly patients leads to increased susceptibility to drug toxicity

17
Q

What happens when drugs compete for metabolism?

A

Accumulation of both drugs, may lead to toxicity

18
Q

What can inhibit CYP3A4?

A

Grapefruit Juice

19
Q

What is an example of drug induction?

A

Drugs can induce the expression of cytochrome P450

20
Q

What is the end result of the metabolism of the drugs?

A
ACTIVE DRUG
1) very lipid-soluble
2) less polar
3) less ionized
4) weak electrolyte
5) more able to penetrate
cell membrane

Convert to….

INACTIVE DRUG
1) less lipid-soluble
2) more polar
3) more ionized
4) strong electrolyte
5) less able to penetrate
cell membranes

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