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NUR 325 > Pharmacology Principles > Flashcards

Pharmacology Principles Flashcards

Exam 1

1
Q

What are the three phases of drug action?

A

Pharmaceutic phase, pharmacokinetic phase, and pharmacodynamic phase

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2
Q

What is the pharmaceutic phase of drug action?

A

Dissolution (the drug begins to dissolve so it can be used).

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3
Q

What is the pharmacokinetic phase of drug action?

A

Drug is moving through the body and what the body does to the drug (absorption, distribution, metabolism, excretion)

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4
Q

What is the pharmacodynamic phase of drug action?

A

What the drug does to the body. The mechanism of action, intended effect of the drug and therapeutic action.

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5
Q

What route does the pharmaceutical phase of drug action only occur with?

A

Oral

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6
Q

What are the four processes of the pharmacokinetic phase of drug action?

A

Absorption (small intestine)
Distribution (through blood)
Metabolism/biotransformation (liver)
Excretion (kidneys)

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7
Q

Describe drugs crossing cell membranes, specifically the phospholipid layer.

A

Drugs must be lipid soluble to pass membrane. Water soluble drug require passage through channels or pores (transport mechanisms)

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8
Q

What is the first pass effect?

A

Metabolism of drug before systemic circulation. The % of drug broken down in the liver before going into systemic circulation.

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9
Q

What is bioavailability?

A

The amount of drug left after first pass

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10
Q

What is the bioavailability of PO medications?

A

Varies (liver takes some of it)

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11
Q

What is the bioavailability of IV medications?

A

100%

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12
Q

What are the three routes of absorption?

A

Enteral, parenteral, and topical (transdermal)

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13
Q

Describe the enteral route of absorption.

A

By way of GI tract (oral/gastric mucosa, small intestine, rectum)

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14
Q

Describe enteric coated enteral route.

A

EC intended to break down in small intestine NOT stomach- first pass effect

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15
Q

Describe oral enteral route.

A

PO break down starts in stomach, absorbed in small intestine- first pass effect

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16
Q

Descibe sublingual, buccal, and rectal enteral route.

A

All highly vascularized tissue- no first pass effect, by-passes liver

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17
Q

Describe the parenteral route of absorption.

A

SQ, IM, IV, intrathecal (into spinal cord), epidural (the space around spinal cord)
IV is the fastest (no barriers to absorption, often irreversible)
Does not go through first-pass effect

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18
Q

Describe topical (transdermal) route of absorption.

A

Application of meds to body surfaces (eyes, skin, ears, nose, lungs)

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19
Q

What is distribution in the pharmacokinetic phase?

A

Distribution is the movement of the drug through the body
Process by which the drug molecules leave the blood stream and arrive at the site of action
Depends largely on adequacy of blood circulation

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20
Q

What could be some disruptions in distribution?

A

Decreased blood flow = decreased distribution (less effective)
Peripheral vascular disease
Abscesses (< blood flow to site due to inflammation)
Tumors

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21
Q

What is the blood brain barrier?

A

Cells in the capillary wall in the brain with very tight junctions that prevent drugs passages.

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22
Q

What drugs can cross the blood brain barrier (BBB)?

A

Only drugs that have a transport system or are lipid-soluble can cross the BBB
(Alcohol, Glucose)

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23
Q

Describe the protein-binding effect during distribution.

A

Temporary storage of drug molecule that allows the drug to be available for a longer period of time
Goal: maintain a steady free drug concentration aka steady state
Remember, only unbound drug is active and free to exert effects

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24
Q

What is the primary plasma protein during the protein-binding effect?

A

Albumin

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25
Q

What happens when the patient has hypoalbuminemia (due to malnutrition or liver disease) during the protein-binding effect?

A

More free drug is available for distribution to tissue site
Possibility of overdose and toxicity

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26
Q

Describe metabolism (biotransformation) during the pharmacokinetic phase.

A

Method by which drugs are inactivated or biotransformed (called a metabolite)

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27
Q

What organ is the major site for drug metabolism?

A

The liver

28
Q

Describe drug metabolism in the liver.

A

Converts lipid-soluble (active) drugs into water-soluble (inactive) metabolites
Kidney can excrete these metabolites
Uses Cytochrome P-450 enzymes to break drugs down

29
Q

Describe metabolism using Cytochrome P-450 enzymes (CYP450).

A

Cytochrome P-450 = a group of isoenzymes that metabolize drugs in the liver
About 1/2 of all drugs metabolized by this system
Drug-drug interactions can occur when drugs metabolized by the same isoenzyme are taken concurrently

30
Q

What is the clinical significance of CYP450?

A

Substrate- if drug uses CYP450 system for metabolism to convert to an active form
Inducer- Speeds up metabolism of CYP450 system. Reduces the amount of drug in body and reduces therapeutic effect
Inhibitor- slows down metabolism of the CYP450 system (> amount of drug in body, > risk of toxicity)

31
Q

What is a known CYP450 inhibitor?

A

Taking grapefruit juice with another drug that uses this system increases the amount of drug in the body
Can lead to toxicity

32
Q

Describe excretion during the pharmacokinetic phase.

A

Elimination of drug from the body- generally, only hydrophilic drugs can be excreted effectively
Kidney is the major site of excretion
Some of the drug is secreted and some is reabsorbed
Important in maintaining a steady state

33
Q

What are the three ways that drugs can be excreted through the kidneys?

A

Glomerular filtration
Tubular secretion
Tubular reabsorption

34
Q

How does kidney disease or dysfunction effect excretion?

A

Decreased excretion = drugs build up and cause toxicity

35
Q

What is the glomerular filtration rate (GFR)?

A

Best measure of kidney function
Calculated from the creatinine level, age, body size, and gender
GFR of drugs is related to free drug concentration in plasma

36
Q

Describe half-life during excretion.

A

Serum half-life (T 1/2) is time required for the serum concentration of a drug to decrease by 50%
Takes 5 half-lives for 97% of drug to be eliminated
T 1/2 varies from drug to drug

37
Q

How many half-lives would it take for “steady state” to occur?

A

4-5

38
Q

When does steady state occur?

A

When intake of drug equals amount metabolized/excreted

39
Q

What does the half-life determine?

A

Dosing interval

40
Q

What is the goal of around the clock dosing (ATC)?

A

Maintain 50% concentration in body

41
Q

What is onset?

A

The time it takes for the drug to elicit therapeutic response (latent period)

42
Q

What is peak?

A

The time it takes for the drug to reach its maximum therapeutic effect

43
Q

What is duration?

A

The time the drug concentration is sufficient to elicit a therapeutic response

44
Q

What is phase 3 of the drug action?

A

Pharmacodynamic phase

45
Q

Describe the pharmacodynamic phase.

A

What the drug does to the body
Drugs may increase, decrease, replace, inhibit, destroy, protect, or irritate to CREATE A RESPONSE
Drugs exert MULTIPLE rather than single effects on the body

46
Q

Describe the role of receptors during the pharmacodynamic phase.

A

Receptors are proteins located on cell surfaces
Chemicals in the body interact with drugs to produce effects
These chemicals BIND with the drug = drug-receptor complex

47
Q

What does an agonist do?

A

Stimulates/activates
A drug that has the ability to INITIATE a desired therapeutic effect by BINDING to a receptor

48
Q

What does an antagonist do?

A

Inhibits/blocks
A drug that produces its action NOT by stimulating receptors but PREVENTING/BLOCKING/INHIBITING other natural substances from binding and causing a response

49
Q

Describe receptor-less activation.

A

Not all drug responses involve receptors
Some drugs act through simple physical or chemical interactions with small molecules

50
Q

What is a therapeutic index?

A

The measure of reltive safety of drug

51
Q

What is a narrow therapeutic index (NTI)?

A

Has a ratio of lowest concentration at which clinical toxicity occurs

52
Q

What is a black box warning?

A

Required by the FDA for drugs that are especially DANGEROUS
Is the strongest safety warning a drug can carry and still remain on the market
Must appear prominently (on package insert, product label, and any advertising)

53
Q

What are medication errors a major cause of?

A

Morbidity and mortality (3rd leading cause of death)

54
Q

Describe the processes to prevent medication errors.

A
  1. Restrict high-alert drugs and medication routes
  2. Practice drug differentiation. Use of “tall-man” lettering for look-alike drug names
  3. Use computerized systems for administering medications
  4. Make patient information readily accessible
  5. Standardize and simplify
  6. Apply reminders
  7. Include the patient in therapy
  8. Don’t use trailing zeros
  9. Use leading zeros
55
Q

What are high alert medications?

A

Institute for Safe Medication Practices (ISMP) identified these drugs to most likely cause serious harm or death
(Insulin, heparin, opioids, injectable potassium chloride, neuromuscular blocking agents, chemotherapy drugs)

56
Q

How do drug interactions occur?

A
  1. Drug- drug. May be intended or unintended. Increased risk with polypharmacy and narrow therapeutic index drugs
  2. Drug- food
  3. Drug- herb
  4. Drug- disease (kidney/liver disease)
57
Q

How can the nurse minimize drug interactions?

A

Minimize the number of drugs the patient receives
Take a thorough drug history- reconcile medications
Be extra vigilant in monitoring when a patient is taking drugs with a narrow therapeutic index

58
Q

Describe how a drug interaction increases therapeutic effects using additive effects.

A

2 drugs taken with similar MOA

59
Q

Describe how a drug interaction increases therapeutic effects using synergism/potentiation.

A

2 drugs with DIFFERENT MOA but result in a combined drug effect greater than that of either drug alone

60
Q

Describe how a drug interaction increases therapeutic effects using activation of drug-metabolizing enzymes in the liver.

A

Decreases metabolism rate of the drug (CYP450 system)

61
Q

Describe how a drug interaction increases therapeutic effects using displacement.

A

Displacement of one drug from plasma protein-binding sites by a second drug increases the effect of displaced drug

62
Q

Describe how a drug decreases therapeutic effects using an antidote.

A

Drug given to ANTAGONIZE (stop) the toxic effects of another drug

63
Q

Describe how a drug decreases therapeutic effects using decreased intestinal absorption.

A

Applies to PO medications

64
Q

Describe how a drug decreases therapeutic effects using activation of drug-metabolizing enzymes in the liver (enzyme inducers).

A

Increased metabolism rate of the drug [quicker out of the system]
CYP450 system

65
Q

Describe older adults and pharmacokinetic consequences.

A

Decreased production of CYO450 enzymes increased risk for drug interactions (can < up to 30%)
Hepatic changes- drugs metabolized more slowly
Cardiac/Circulatory changes- impaired circulation = decrease distribution of drugs
Gastrointestinal changes- decreased absorption of oral drugs
Renal changes- drugs excreted less completely

66
Q
A

NUR 325 (7 decks)

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