Pharmacokinetic Principles Flashcards

1
Q

Pharmacokinetics

A

the study of the action of the body on drugs

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2
Q

Pharmacodynamics

A

the study of the action of drugs on the body

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3
Q

Therapeutic Range

A

the concentration of drug in the blood above which the risk of side effects or complications outweigh the benefits and below which therapeutic benefits are not seen

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4
Q

Bioavailability

A

the fraction or percentage of the drug that reaches the systemic circulation

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5
Q

First Pass Effect

A

blood from GI tract passes through the liver before systemic circulation; some drugs are significantly metabolized by the liver before reaching systemic circulation

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6
Q

A drugs with a high first pass rate has a _____ bioavailability and should not be given _______.

A

Lower; PO

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7
Q

Passive DIffusion

A

High concentration to low concentration

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8
Q

Active transport and saturable kinetics

A

Specific carrier proteins carry drugs across bilayer; saturable kinetics explains that there are only so many proteins to carry the drug

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9
Q

Factors that influence drug absorption

A

ionization state, molecular weight, solubility, formulation

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10
Q

Drugs that permeate the plasma membrane most readily

A

Small, non-ionized, lipid-soluble drugs

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11
Q

Patient associated factors

A

Presence of food in GI tract, stomach acidity, blood flow to the GI tract, gastric emptying time

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12
Q

Advantages of PO

A

Patient convenience and storage

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13
Q

Disadvantages of PO

A

Non-emergent use, Must pass through GI tract, First pass effect

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14
Q

Advantages of SL

A

Avoids first pass effect Rapidly absorbed

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15
Q

Disadvantages of SL

A

Limited by volume and sublingual absorption

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16
Q

Advantages of PR

A

Unconscious or vomiting patients
Children
1° treat local conditions

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17
Q

Disadvantages of PR

A

Comfort

Unreliable absorption

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18
Q

Advantages of IV

A

Rapid onset
F = 100%
Emergency
NPO

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19
Q

Disadvantages of IV

A

Must be soluble in water

Increased risk

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20
Q

Advantages of IM

A

Quick onset

Avoids stomach

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21
Q

Disadvantages of IM

A

Erratic absorption

Increased risk; pain

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22
Q

Advantages of SC

A

Less painful than IV or IM

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23
Q

Disadvantages of SC

A

Slower, sometimes erratic absorption

Limited volume

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24
Q

Advantages of Inhalation

A

Rapid onset

Local effect

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25
Q

Disadvantages of Inhalation

A

Technique

Potential alveolar irritation

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26
Q

Advantages of Intranasal

A

Local effect

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27
Q

Disadvantages of Intranasal

A

Comfort

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28
Q

Advantages of Topical

A

Local delivery

29
Q

Disadvantages of Topical

A

Patient ease

30
Q

Advantages of Transdermal

A

Avoids GI tract

Convenience

31
Q

Disadvantages of Transdermal

A

Local irritation

32
Q

Pharmacology

A

the study of drugs and their origin, nature, properties, and effects upon living organisms

33
Q

Pharmacotherapy

A

the use of medicine in the treatment of disease

34
Q

Important Guiding Principles

A

• Justifiable and documented indication for every medication; Use newly approved medications only when there are clear advantages over older medications; Simplify medication regimen to enhance patient adherence; Consider lifestyle modifications when indicated before medication therapy; Recognize possible reasons for the failure of medication regimens

35
Q

Factors That Influence Drug Distribution

A
  • Blood flow to the area of action
  • Membrane permeability
  • Plasma protein binding
36
Q

Volume of Distribution

A
  • The apparent volume into which a drug distributes in the body at equilibrium
  • The volume that would be required to contain the administered dose if that dose was evenly distributed in blood or plasma
37
Q

Volume of Distribution formula

A

Vd= amount in body (mg) / Plasma drug concentration (mg/L)

38
Q

Small Vd

A

hydrophilic-trapped in plasma

39
Q

Large Vd

A

lipophilic-distributes into tissues

40
Q

Metabolism

A

most drugs are biotransformed or metabolized (primarily by the liver) before they can be eliminated; this process usually makes the drug more water soluble

41
Q

Phase I Reactions

A

oxidized or reduced to more polar form

Cytochrome P450 system

42
Q

Substrate

A

drug metabolized by Cytochrome P450 system (most lipophilic drugs)

43
Q

Inducer

A

drug that causes more rapid metabolism of substrate drugs, e.g. chronic EtOH

44
Q

Inhibitor

A

drug that causes slower metabolism of substrate drugs, e.g. cimitidine

45
Q

Phase II Reactions

A

polar group is conjugated to the drug → increased polarity

46
Q

Prodrug

A

inactive substance metabolized to an active substance within the body

47
Q

Active Metabolite

A

metabolite that also has therapeutic activity

48
Q

Factors that Influence Metabolism

A

Hepatic dysfunction
Severe CHF
Advanced age

49
Q

Elimination

A

drugs are excreted from the body after being metabolized to a more polar form; others are excreted unchanged, usually in the urine.

50
Q

Filtration

A

drugs diffuse from blood to nephron (small, unbound, nonionic)

51
Q

Secretion

A

active transport of drug into nephron

52
Q

Reabsorption

A

drugs reabsorbed into the blood stream by diffusion from the nephron tubule (small, nonionic)

53
Q

Factors that Influence Elimination

A

Renal dysfunction

54
Q

Half-life (t1/2)

A

the time it takes the plasma concentration of a drug to decrease by 50% after a given dose; Example: heparin vs. warfarin

55
Q

Steady State

A

absorption = elimination; the drug in the body is in a state of homeostasis; generally reached in 5 half-lives

56
Q

Receptor

A

the component of a cell or organism that interacts with a drug and initiates the chain of biochemical events leading to the drug’s observed effects

57
Q

Agonist

A

alters the physiology of a cell by binding to plasma membrane or intracellular receptors

58
Q

Antagonist

A

inhibit or block responses caused by agonists

59
Q

Factors Effecting Pharmacokinetics and Pharmacodynamics

A
	Genetics
	Age
	Gender
	Ethnicity
	Diet and nutrition
	Pathophysiology
60
Q

Pharmacokinetic Drug Interactions

A
Caused by alterations in
Absorption 
Distribution
Metabolism
Elimination
61
Q

Pharmacodynamic Drug Interactions

A

Addition, synergism, potentiation, antagonism

62
Q

Bioequivalence

A

drugs that have the same effect on the body and a nearly identical chemical structure

63
Q

Therapeutic Equivalence

A

drugs that have essentially the same effect on the body, but do not have an identical chemical structure

64
Q

Loading Dose

A

an initial dose that is larger than subsequent doses for the purpose of achieving therapeutic drug concentrations more rapidly; LD = Vd X Cp

65
Q

Maintenance Dose

A

the dose of drug that attempts to maintain a steady state plasma concentration in the therapeutic range

66
Q

Addition

A

Addition: 1+1 = 2

67
Q

Synergism

A

Synergism: 1+1 = 3

68
Q

Potentiation

A

Potentiation: 0+1 = 2

69
Q

Antagonism

A

Antagonism: 1+1 = 0