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NUR 325 PATHO > Pharmacology Principles (Exam 1) > Flashcards

Pharmacology Principles (Exam 1) Flashcards

1
Q

Three Phases of Drug Action

A
  1. Pharmaceutic Phase
  2. Pharmacokinetic Phase
  3. Pharmacodynamic Phase

When anyone takes a single medication that drugs has to go through all three of these process

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2
Q

Phase 1: Pharmaceutic Phase

A

-Dissolution of the drug occurs so it can be used and absorbed

-Tablet to granules to smaller particles to solution to be absorbed into the blood.

-Only occurs with oral drugs

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3
Q

2 stages of the Pharmaceutical Phase

A

Disintegration phase

Dissolution phase

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4
Q

Phase 2: Pharmacokinetic Phase

A

What the body does to the drug.

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5
Q

4 phases of the Pharmacokinetic Phase

A
  1. Absorption
    (After dissolution in the stomach, it moves to the small intestines so it can be absorbed into blood)
  2. Distribution
    (The drug leaving the blood by passing through the cell membrane to intended to carry out its affect)
  3. Metabolism/Biotransformation
    (Liver metabolizes the drug to lipid soluble metabolite to water soluble metabolite
  4. Excretion
    (Then travels so the kidney can excrete the drug)
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6
Q

Giving a drug IV

A

The drug starts the the distribution phase of the phramacokinetic phase. There is no absorption because it is being injected directly into the blood stream

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7
Q

What organ metabolizes

A

The liver

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8
Q

What organ excretes

A

The kidney

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9
Q

Phospholipid Layer

A

Semipermeable Layer

Tightly packed together

Drug can pass through if it is lipid soluble. (Can pass through lipid layer)

Water soluble drugs might require transport carriers

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10
Q

First Pass Effect

A

-Absorption effects the metabolism of drug before systemic circulation

-% of drug broken down in the liver

-It is the liver taking a toll or tax which affects the bioavailability of the drug

-If you take 40 mg of drug orally it is not 100% bioavailability because the liver will take a percentages

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11
Q

Bioavailablity

A

The amount of drug left after first pass

Bioavailibitly of PO varies

Bioavalibilty of IV is 100%

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12
Q

Three routes of Absorption

A

Enteral

Parenteral

Topical Transdermal

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13
Q

Enteral Route of Absorption

A

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

EC intended to break down in small intestine NOT stomach. First Pass

PO break down starts in stomach absorbed in small intestine. First Pass

SL, Buccal, Rectal all highly vascularized tissue. NO first pass effect. By-passess the liver

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14
Q

Parenteral

A

-SQ, IM IV intrathecal (into spinal canal), epidural (the space around the spinal cord)

-IV is the fastest (no barriers to absorption, often irreversible)

-Does not go through the first-pass effect

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15
Q

Topical (Transdermal)

A

-Application of meds to body surfaces

-Eyes, skin, ears, nose, lungs

-Localized so no first pass

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16
Q

Pharmacokinetic Phase: Distribution

A

-The movement of the drug through the body

-Process by which the drug molecules leave the blood stream and arrive at site of action

-Depends largely on adequacy of blood circulation

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17
Q

Decreased blood flow equals

A

Decreased distribution

If someone has peripheral vascular disease, abscesses, or tumors it decrease the blood flow to that area which results in the drug not being able to reach that area

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18
Q

Distribution: Blood Brain Barrier (BBB)

A

Affects distribution

Cells in the capillary wall in the brain with even more tight junctions which prevent drug passages

Only drugs with a transport system or EXTREMELY lipid soluble can pass through the BBB

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19
Q

Distribution: Blood Brain Barrier (what can cross)

A

Alcohol can cross the BBB

Glucose can cross the BBB (energy)

Not fully developed in infants

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20
Q

Distribution: Protein-Binding Effect.

A

-Temporary storage of the drug molecule that allows drug to be available for a longer period of time

-Drug Ratio of bound to unbound (free) molecules varies

-Binding is reversible (a rapid process)

-Only the ubound drugs is active and free to exert effects

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21
Q

Distribution: The goal when we have a medication that has a high protein binding effect

A

-Maintain a steady state of free drug concentration aka steady state because only ubound drugs are free to exert effects

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22
Q

Distribution: What effects protein-binding?

A

-The amount of protein in a persons blood

-Albumin is the primary plasma protein

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23
Q

Hypoalbuminemia (Malnutrition or liver disease)

A

-More free drug is available for distribution to tissue site

-Possibility of overdose and toxicity

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24
Q

Protein-Binding Example

A

warfarin/Coumadin

-Drug used to decrease coagulation (Blood thinner)

-Very highly protein bound (97-99%), leaves 1-3% free to exert effect

-A client with low albumin = less bound warfarin and more free warfarin

-More free warfarin can exert effect which increases the risk of toxicity and increase bleeding

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25
Q

Pharmacokinetic Phase: Metabolism

A

-Aka- Biotransformation

-Method by which drugs are INACtivated or biotransformed into a metabolite

-Live is the major site for drug metabolism. It can convert lipid-soluable drugs into water soluble metabolites. Kidney can excrete these metabolites.

26
Q

What enzyme is responsible for turning lipid soluble drugs into water soluble drugs

A

Cytochrome P-450

27
Q

If your liver isn’t working than you can have drug toxicity why?

A

Because you can not break drug down into inactive and have to much drug build up within the system

28
Q

Metabolism: CYP450

A

-A group of isoenzymes that metabolize drugs

-About half of all drugs are metabolized by this system

-Drug-drug interactions can occur when drugs metabolized by the same isoenzyme are taken concurrently

29
Q

Metabolism: CYP450: Clinical Significance

A

-Substrate: If a drug uses CYP450 system for metabolism. Pro-drug: is a substrate that uses the CYP450 system to convert to an active form

-Inducer: Speeds up metabolism of the CYP450 system. Reduces the amount of drug in the body. Reduces the therapeutic effect

-Inhibitor: slows down metabolism of the CYP450 system. Increases the amount of drug in the body. Increases risk of toxicity

30
Q

If a drug is a CYP450 inhibitor

A

It can cause of build of medications in the liver because they are not being brokendown

31
Q

If a drug in a CYP450 Inducer

A

It can cause a decrease in the amount of drug in the body because the liver is working overtime. this reduces therapeutic effect.

32
Q

CYP450 Inhibitor Example

A

-Grapefruit juice is a CYP450 inhibitor. Taking grapefruit juice with another drug that uses the CYP450 system can cause an increase in the amount of drug in the body. This leads to toxicity

33
Q

Pharmacokinetic Phase: Excretion

A

-How the drugs are complete removed from the body. Must be water soluble.

-Hydrophilic drugs can be excreted effectively

-Kidney is the major site. Through glomerular filtration. Tubular secretion. Tubular reabsorption

34
Q

Pharmacokinetic Phase: Excretion. Reabsorption and Secretion

A

-Some of the drug is secreted

-Some of the drug in reabsorbed

35
Q

Important in maintain a steady state while in excretion

A

90% of Penicillin G is excreted through the kidney so very little is reabsorbed so the drug would need to be given more frequently to maintain steady state

36
Q

To maintain steady state

A

You can give high dose of drug or give drug more frequently

37
Q

Pharmacokinetic Phase: Excretion. Kidney disease

A

Decreased excretion = drug build up and cause toxicity

Renal labs = blood urea nitrogen (BUN), creatinine

38
Q

Best measure of kidney fuction

A

GFR. Glomerular filtration rate.

Calculated from the creatinine level, age, body size, and gender.

39
Q

Elimination: Half-Life

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.

40
Q

Takes about _____ half lives for steady state to occur

A

4-5

41
Q

When does steady state occur?

A

When intake of drug equals amount metabolized/excreted

42
Q

One time dose of morphine 10 mg is given at 12:00. T 1/2 is 3 hours

A

1500 = 5 mg

1800 = 2.5 mg

21 = 1.25 mg

2400 = 0.625 mg

0300 = 0.313 mg

43
Q

Around the Clock Dosing (ATC)

A

-Goal is to maintain 50% concentration in body

44
Q

ATC Example: Morphine 10 mg given every 3 hours (ATC)

A

-After about 4 does there would be a constant level or “steady sate” of 5 mg at all times

-Serum concentration maintained at 50%

45
Q

Onset, Peak, Duration

A

-Onset: time it takes for drug to elicit therapeutic response (latent period)

-Peak: time it takes for drug to reach its maximum therapeutic effect

-Duration: Time drug concentration is sufficient to elicit a therapeutic response

46
Q

Phase 3 of Drug Action: Pharmacodynamic Phase

A

What the drug actual does to the body.

Drugs my increase, decrease, inhibit, destroy, protect or irritate to create a response

Drugs can exert multiple effects on the body

47
Q

Multiple Effects: Example

A

Drug name: Metaproternonal

MOA: Broncho dilator

Uses: Acute asthma attack or COPD

Adverse effects: Tachycardia and Palitations

Multiple effects: Desired is dilates bronchial passage. Not desired: tachycardia or palpitiations

48
Q

Pharmacodynamics: Receptors

A

-Receptors are proteins located on cell surfaces

-Chemicals in the body that interact with drugs to produce effects

-These chemical bind with the drug = drug-receptor complex

49
Q

When a drug binds with a receptor a drug receptor complex forms.

A

This complex initiates a physiochemical reaction

agonist = stimulates/activates

antagonist = inhibits/blocks

50
Q

Receptor Theory of Drug Action: Agonist

A

-A drug that has the ability to INITIATE a desired therapeutic effect by BINDING to a receptor

Example: Isoproterenol = beta1 adrenergic AGONIST. So this binds to a beta receptor and causes vasodilation lowering peripheral vascular resistance

51
Q

Receptor Theory of Drug Action: Antagonist

A

A drug that produces its acton NOT by stimulation receptors but PREVENTING or BLOCKING or INHIBITING other natural substances (ligands) from binding and causing a response

Examples:

Ranitidine/Zantac, an H2 ANATGONIST. Blocks the release of gastric acid

diphenhydramine, an H1 ANTAGONIST, blocks action of histamine

52
Q

Receptor-Less Activation

A

Not all drug responses involve receptors

53
Q

How do we determine what drug are worrisome or not?

A

-Therapeutic index is the measure of relative safety of drug.

NTI have a ratio of lowest concentration at which clinical toxicity commonly occurs. If it is 10 then 10.1 causes toxicity

Therapeutic levels checked to ensure the medication is dosed effectively but avoid toxicity

54
Q

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

-Black Box warning has to be present on package, label, and advertising

55
Q

Adverse Drug Reaction and Medication Errors

A

-Med errors are a major cause of morbidity and mortality

-Third leading cause of death

56
Q

Drug Drug interactions

A

-May be intended

-May be unintended

-Increased risk with polypharmacy and NTI drugs

-Drug FOOD interaction
-Drug HERB
-Drug DISEASE

57
Q

How can the nurse minimize drug interactons?

A

-Minimize the number of drugs the patient receives

-Take a thorough drug history

-Be extra vigilant in monitoring when patient is taking drug with NTI

58
Q

Drug interactions that INCREASE Therapeutic Effects

A

-Additive effects: 2 drugs taken with similar MOA. (2 antibiotics given together to treat a complicated infection)

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

Activaiton of drug-metabolizing enzymes in the liver-decreases metabolism rate of the drug CYP450 system

Displacement: Displacement of one drug from plasma protein binding sites by a second drug — increases effect of displaced drug

-

59
Q

Drug interactions that decrease therapeutic effects.

A

Antidote: Drug given to ANTAGONIZE the toxic effects of another drug

Decrease Intestinal Absorption: If drug can not be broken down they will never get the therapeutic effects of the drug

Activation of drug-metabolizing enzymes in the liver—enzym inducers. Increase metabolism rate of the drug = quicker out of system. CYP450 system

60
Q

Older Adults and Pharmacokinetic Consequences

A

Hepatic Changes. Drugs metabolized more slowly

Cardiac and Circulatory changes. Impaired circulation = decrease distribution of drugs

Gastrointestinal Changes = Decreased absorption of oral drugs

Renal Changes = Drugs excreted less completely

Decrease production of CYP 450 enzymes increase risk for drug interactions

NUR 325 PATHO (30 decks)

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