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Nursing Pharmacology > Module 4 > Flashcards

Module 4 Flashcards

1
Q

Enzyme-mediated alteration of a drug’s structure

A

Metabolism

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2
Q

What are the different sites of drug metabolism?

A

Liver, intestine, stomach, kidney, intestinal bacteria

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3
Q

What is another term for metabolism?

A

biotransformation

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4
Q

What is the primary site of drug metabolism?

A

The liver

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5
Q

What are some common exogenous toxins?

A

Meat, wine/alcohol, cigarettes, coffee, drugs, vegetables

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6
Q

What are the different therapeutic consequences of drug metabolism?

A 
Increase water solubility of drugs to promote their excretion
Inactivate drugs
Increase drug effectiveness
Activate pro-drugs
Increase drug toxicity
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7
Q

What are some essential endogenous molecules provided by metabolism?

A

Vitamin D, bile acids, cholesterol, steroids, bilirubin

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8
Q

In most clinical situations, drug metabolism follows ____ order kinetics

A

first

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9
Q

Describe first order kinetics.

A

There is more enzyme than drug; therefore drug metabolism is directly proportional to the concentration of free drug

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10
Q

In first order kinetics, a constant _______ of drug is metabolized per unit time.

A

fraction

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11
Q

Describe zero order kinetics.

A

Plasma drug concentration > enzymes

Drug metabolism is constant over time

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12
Q

In zero order kinetics, a constant ________ of drug is metabolized per unit time.

A

amount

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13
Q

What is the best example of zero order kinetics?

A

Ethanol

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14
Q

In this metabolism kinetics, drug metabolism is independent of drug concentration.

A

Zero order

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15
Q

Where can first pass metabolism occur?

A

Hepatocytes in the liver
intestinal enterocytes
Stomach
Intestinal bacteria

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16
Q

What is the result of 1st pass metabolism?

A

A decreased amount of parent drug that enters the systemic circulation

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17
Q

What is an example of first pass metabolism in the stomach?

A

Alcohol –> Alcohol DH –> acetaldehyde

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18
Q

High ER drugs

  • have _____ oral bioavailability (-%)
  • PO does are usually ______ than IV doses
  • _____ change sin hepatic enzyme activity produce _______ changes in bioavailability
  • ______ susceptible to drug-drug interactions
A

low - 1-20%
higher (much)
small, large
very

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19
Q

Low ER drugs

  • have _____ oral bioavailability
  • PO doses are ______ to IV doses
  • ______ changes in hepatic enzyme activity have _______ effect on bioavailability
  • __ ______ susceptible to drug-drug interactions
  • Take ______ passes through the liver via the systemic circulation before they are completely metabolism
A 
high
similar
small, little
not very
many
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20
Q

What are the two phases of drug metabolism?

A

Phase I and Phase II

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21
Q

Phase I metabolism
- Convert _______ drugs to more ______ molecules by ________ or ________ polar functional groups such as ______ or ______

A

lipophilic, polar, introducing or unmasking

hydroxyl, amines

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22
Q

What are the different types of reactions in phase I metabolism?

A

Hydrolysis, oxidation, reduction

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23
Q

Phase I metabolism is mediate by what enzymes?

A

Cytochrome p450 enzymes (main), esterases, dehydrogenases

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24
Q

Describe the activity of the resulting metabolites of phase I metabolism.

A

More active, less active or equally as active as the parent drug

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25
Phase II metabolism | - Increases the _______ of ________ drugs by _______ reactions
polarity, lipophilic, conjugation
26
What are different conjugates of phase II metabolic reactions?
Glucuronic acid, sulfate, acetate or amino acids
27
Describe the activity of metabolites of phase II metabolism.
Less active than the parent drug - except morphine-6-glucuronide (more potent analgesic than morphine)
28
Where is the intracellular site of phase I drug metabolism?
Phase I drug metabolizing enzymes are localized to the smooth endoplasmic reticulum
29
Where is the intracellular site of phase II drug metabolism?
Phase II drug metabolizing enzymes are localized predominantly in the cytosol of the cell; except with glucuronidation, which is localized to the smooth ER
30
Largest family of drug metabolizing enzymes.
CYPs (Cytochrome P-450)
31
The majority of drug metabolism in the body is performed by _______ CYP enzymes. CYPs are the predominant phase ___ drug metabolizing enzyme system.
hepatic | phase I
32
How do CYP enzymes work, i.e. metabolize?
Oxidize drugs by adding oxygen, producing water as a by-product
33
How does malnutrition affect CYP activity?
Can decrease it as these enzymes require dietary protein, iron, folic acid and zinc for full activity
34
Describe the nomenclature of CYP enzymes. | CYP3A4 for example.
3 - family A - sub-family 4 - isozyme
35
_________ metabolizes the largest fraction of currently marketed drugs.
CYP 3A4
36
What are the different phase II drug metabolizing enzymes?
``` UDP-glucuronosyltransferases (UGTs) Sulfotransferases (SULTs) Glutathione S Transferases (GSTs) N-acetyltransferases (NATs) Thiopurine Methyltransferases (TPMT) ```
37
Which phase II drug metabolizing enzyme type metabolizes drugs the most?
The fraction of drugs metabolized is equally split between UGTs, SULTs, GSTs, and NATs
38
Where are UGTs localized? What do they catalyze transfer or? Describe the effect of the enzyme on the parent drug. How many UGT enzymes are there in humans?
Smooth ER glucuronic acid Glucuronidated drugs are more polar and more easily excreted 19
39
Where are SULTs localized? What do they add? Describe the metabolite. How many SULT enzymes are there in humans?
Cytosol Add sulfate to hydroxyl groups of drugs Sulfated drugs are more polar and more easily excreted 11
40
Where are GSTs localized? What do they add? What is the result of transfer? How many GSTs are there in humans?
Cytosol (main) or microsomal Add GSH (glutathione) Intracellular anti-oxidant --> causes a reactive drug to be less toxic 20+
41
Where are NATs localized? What do they add? What are they subject to? How many are there in humans?
Cytosolic Acetyl group from Acetyl-CoA Subject to genetic polymorphisms - variability in drug response 2 - NAT1 and NAT2
42
Where are TPMTs localized? What do they add? What are they subject to?
Cytosolic Add methyl from S-adenosylmethionine Subject to genetic polymorphisms, can have dramatic effects on drug safety
43
What are the major factors that affect drug metabolism?
Age drug interactions disease state Genetic polymorphisms
44
Describe how age affects metabolism.
Infants have almost no hepatic CYP activity - takes babies approx. 1 year after birth until they have a reasonable level of drug metabolizing enzymes By age 2 - same level as adults
45
Process where a cell synthesizes an enzyme in response to a drug or other chemical.
Enzyme induction
46
Consequence of CYP induction.
Increased drug metabolism
47
What are consequences of increased drug metabolism?
Decreased plasma concentration Decreased drug activity Increased drug activity
48
_______ induces some drug metabolizing enzymes
smoking
49
What is the consequence of CYP inhibition?
Decreased drug metabolism
50
Decreased drug metabolism has the following consequences.
Higher plasma concentration Increased therapeutic effect Increased drug toxicity
51
What are diseases that decrease CYP activity?
Liver disease kidney disease inflammatory diseases infection
52
SNPs affect what?
the protein
53
What are the common phase I SNPs?
CYP2C9 | CYP2D6
54
What are the common phase II SNPs?
UGT1A1 | NAT2
55
``` CYP2C9 metabolizes what? Polymorphism results in what? Describe the effect on dosage. What may occur if the dosage is not altered? ```
Metabolizes warfarin Polymorphism results in decreased activity/metabolism Dosage must be lowered in these patients, else extensive bleeding may occur
56
CYP2D6 Metabolizes what? What phenotypes are possible?
Codeine to morphine | URM, EM, IM, PM
57
Describe EM.
Extensive metabolizers - considered to have normal enzymatic activity
58
Describe IM. PM.
IM - lower metabolic activity | PM - almost no metabolic activity (i.e. no pain relief)
59
Describe URMs.
Ultra-rapid metabolizers - significantly increased CYP2D6 activity - possess multiple copies of CYP2D6 gene
60
UGT1A1 Metabolizes what? Polymorphisms cause what? What are patients with the polymorphism at increased risk of?
Metabolizes SN-38 - anti-cancer compound (inactivates) Polymorphisms decrease its activity Patients with UGT1A1 are at increased risk for diarrhea and dose-limiting bone marrow suppression
61
NAT2 Metabolizes what? Number of polymorphisms here? Possible phenotypes?
Metabolizes isoniazid (TB), caffeine, cancer causing chemicals 23+ Rapid or slow acetylators
62
Describe slow acetyaltors and the effect with isoniazid.
More susceptible to isoniazid toxicity (neuropathy, hepatotoxicity) - higher risk of developing certain types of cancers

Nursing Pharmacology (30 decks)

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