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MT6314 (PCOL) > Drug Biotransformation > Flashcards

Drug Biotransformation Flashcards

1
Q

It is the mechanism by which the body terminates the action of some drugs

A

Drug Metabolism

In some cases, it serves to activate prodrug

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2
Q

Types of Metabolic Reactions

What phase is described by the following:
- Non-synthetic reactions
- Converts the parent drug to a more polar conjugate (water soluble) or more reactive product
- Introducing/inserting/unmasking a polar functional group
- OH, SH, NH2

A

Phase I

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3
Q

What are the different types of reactions under Phase I?

A
  1. Oxidation
  2. Reduction
  3. Deamination
  4. Hydrolysis
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4
Q

What phase is described by the following:
- Synthetic reactions
- Endogenous substrate is conjugated to the parent drug to make it more polar

A

Phase II

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5
Q

What are the different types of reactions under Phase II?

A
  1. Glucoronidation-glucoronic acid
  2. Acetylation-acetyl CoA
  3. Sulfation
  4. Methylation
  5. Glycine conjugation-glycine
  6. Glutathione conjugation
  7. H2O conjugation
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6
Q

True

Most drugs go through Phase I, initially then Phase II

A

True

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7
Q

What drug is this:
- Maybe metabolized by gastric fluid
- Must be given 2 hours before meals
if given through the oral route

A

Penicillin

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8
Q

True or False

Penicillin is an example of a Gastric Acid

A

True

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9
Q

True or False

Insulin is an example of a Gastric and digestive enzyme

A

True

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10
Q

True or False

Epinephrine is an example of aIntestinal wall enzymes

A

True

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11
Q

What is the most important organ for drug metabolism

A

Liver

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12
Q

It contains high concentration of PHASE I enzymes

Activity of these enzymes require
* NADPH (reducing agent)
* Molecular form of oxygen

A

Smooth Endoplasmic Reticulum (SER)

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13
Q

Determinants of Biotransformation Rate - Genetic Factors

  • Its duration of action is 5 minutes

In 1/2500:
- Abnormal form of this enzyme
- Neuromuscular paralysis may last for hours

A

Hydrolysis of Esters

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14
Q

Determinants of Biotransformation Rate - Genetic Factors

A
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15
Q

Determinants of Biotransformation Rate - Genetic Factors

  • Isoniazid (INH)
  • hydralazine, and procainamide
A

Acetylation of Amines

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16
Q

Determinants of Biotransformation Rate - Genetic Factors

  • Individuals deficient in acetylating capacity
  • Prolonged or toxic responses to normal doses of this drug
A

Acetylation of Amines - Slow Acetylators

17
Q

Determinants of Biotransformation Rate - Genetic Factors

  • Dextrometorphan, metoprolol and some tricyclic antidepressants
  • Oxidation by P450 isoenzymes are genetically
    predetermined
A

Oxidation

18
Q

Determinants of Biotransformation Rate - Individual Differences

Examples of this factor are the following:
- Charcoal inhibits the effect of the drug
- Grapefruit juice increases the amount of drug in the body

A

Diet and environmental factors

19
Q

Determinants of Biotransformation Rate | True or False

Age and Sex:
Drug metabolites differ in young and old

A

True

20
Q

True or False

Males metabolize drugs faster than
females

A

True

21
Q

Give on disease that affects drug metabolism

A

Hyperthyroidism

22
Q

Determinants of Biotransformation Rate

  • It Increase rate of synthesis of the enzyme
  • Reduces the rate of degradation of the enzyme
  • May also induce self metabolism of the drug
  • May also induce metabolism of other drugs and reduce its effects
A

Enzyme Induction

23
Q

Give some enzyme inducers

A
  • Enzyme inducers
  • Phenobarbital
  • Carbamazepine + drug = decreased effects
  • Phenytoin
  • Rifampicin
24
Q

Determinants of Biotransformation Rate

  • It Inhibits CP450
  • Metabolism of the drug is diminished
  • Increase effect of the drug
A

Enzyme Inhibition

25
Q

Give some enzyme inhibitors

A
  • Amiodarone
  • Cimetidine
  • Ketoconazole + drug = increased effect
  • Ritonavir
  • Furanocoumarin
26
Q

Types of Drug Interaction Mechanism

It affects drug action

A

Altered metabolism

27
Q

Types of Drug Interaction Mechanism

This is an example of what absorption:
Cholestyramine inhibits the effect of digoxin when combined with it

A

Altered absorption

28
Q

What are the types of Drug Interaction Mechanism?

A
  • Altered Absorption
  • Altered Metabolism
  • Altered Plasma binding protein
  • Altered Excretion
29
Q

Types of Drug Interaction Mechanism

This is an example of what absorption:
- Probenecid inhibits the secretion of acids
- Penicillin inhibits the excretion of probenecid

A

Altered Excretion

30
Q

Drug Interaction

  • Its response is elicited by combined drugs is equal to the combined response of the individual drugs
  • 1 + 1 = 2
  • e.g. Sedative + ethanol
A

Additive

31
Q

Drug Interaction

  • Its response is elicited by combined drugs is greater than the combined responses of each individual
  • 1 + 1 = 3
  • e.g. Penicillin G removes the cell wall, Gentamicin inhibits production of protein
A

Synergistic

32
Q

Drug Interaction

  • Drug which has no effect enhances the effect of the second drug
  • 0 + 1 = 2
  • e.g. Cimetidine + anticoagulant
    (enhances the anticoagulation)
A

Potentiation

33
Q
  • Drug inhibits the effect of another drug
  • 1 + 1 = 0
  • e.g. Heparin + protamine
A

Antagonism

MT6314 (PCOL) (6 decks)

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