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HLSC 222- midterm 1 > pharmacokinetics > Flashcards

pharmacokinetics Flashcards

1
Q

Pharmacokinetics

A

what body does to drug

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2
Q

Pharmacodynamics

A

what drugs do to body

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3
Q

4 phases of Pharmakinetics

A

(1) Absorption - administration–> blood
(2) Distribution - blood –> cells
(3) Metabolism - enzymatic alteration
(4) Excretion - metabolites –> out of body

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4
Q

Major barrier for drugs to pass through cell

A

Cytoplasmic membrane

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5
Q

How can drugs pass through cytoplasmic membrane

A

(1) membrane transport system (Generally Selective)
(2) Lipophilic drugs: penetrate membrane
(3) Polar drugs/ Ions - not able to cross

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6
Q

Absorption Rate

A

How SOON effects begin

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7
Q

Absorption Amount

A

how INTENSE effects are

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8
Q

Enteral

A

GI tract/ absorption via mouth/anus

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9
Q

Paraenteral

A

outside of GI tract

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10
Q

Topical

A

applied outside body

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11
Q

What affects Drug Absorption?

A

(1) Rate of dissolution - fater = increased absprotion rate
(2) Surface Area - larger SA = faster absorption rate
(3) Blood Flow- high blood flow = faster absorption rate
(4) Lipid solubility - increased solubility = rapid absorption
(5) Plasma pH- enhanced with greater difference between plasma and administration site
- drug molecules have greater tendency to be ionized in plasma

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12
Q

What are the different ways absorption can happen

A

(1) By mouth
(2) IV
(3) IM
(4) Topical
(5) Inhaled
(6) Rectal Suppositories
(7) Vaginal Suppositories
(8) Direct Injections

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13
Q

Barriers to Absorption by mouth

A

(1) GI tract epithelium - main
(2) Capillary wall

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14
Q

What causes fluctuations in absorption by mouth

A

(1) drug solubility
(2) GI tract ph.
(3) food in gut
(4) coadministration of other drugs
(5) special coatings on drugs

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15
Q

Advantages of oral route

A

(1) easy/ convenient
(2) safe
(3) potentially reversable

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16
Q

Disadvantages of Oral route

A

(1) high variability of absorption
(2) inactivation of certain drugs
(3) patient requirements (cooperation, consciousness)

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17
Q

What is the general route of by mouth

A

GI tract –> portal vein –> liver

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18
Q

What are the possible outcomes of drugs when they go through the liver

A

(1) uneventful
(2) extensive hepatic metabolism
(3) enterohepatic recirculation

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19
Q

Barriers to absorptionIV route

A

NONE
- goes directly into blood

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20
Q

What are the fluctuations in IV absorption

A

NONE
-instant and complete

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21
Q

IV advantages

A

(1) rapid, precise, permits use of large volume
(2) permits use of irritant drugs

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22
Q

IV Disadvantages

A

(1) inconvenient
(2) irreversible
(3) Infection
(4) Embolism

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23
Q

Parenteral Routes

A

Intramuscular (IM)

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24
Q

Barriers to Parenteral absorption

A

Only the capillary wall

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25
Q

Parenteral Advantages for absorption

A

(1) administration of poorly soluble drugs
(2) depot preparations –> drug is slowly absorbed

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26
Q

Disadvantagesof IM injections

A

(1) Inconvenient
(2) Discomfort
(3) Local tissue Injury
(4) Nerve damage

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27
Q

Subcutaneous (SubQ)

A

under the skin
almost identical to IM

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28
Q

Topical administration

A

local therapy
transdermal absorption into systemic circulation

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29
Q

Inhaled Administration

A

local effects on lungs

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30
Q

Rectal Suppositories administration effects

A

local or general

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31
Q

Vaginal suppositories effects

A

treat local disorders

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32
Q

Direct Injections

A

directly in heart, joints, or nerves

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33
Q

What factors effect Distribution

A

(1) Blood Flow
(2) Drug’s ability to exit vascular system
(3) Drugs ability to enter cells

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34
Q

How do drugs exit the vascular system

A

(1) Capillary beds
(2) Blood Brain Barrier (BBB)
(3) Placental Drug Transfer
(4) Protein Binding

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35
Q

How do drugs exit the BBB

A

-lipid soluble drugs can pass through the membrane
-some drugs can use transport system

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36
Q

BBB protective component

A

PGP

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37
Q

What is PGP

A

a transporter that pumps drugs out of cells back into blood
- limits access to brain

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38
Q

How do drugs pass through the placenta

A

Lipid-soluble, non-ionized compounds pass from maternal blood to fetus.
- ionized, highly polar, and protein bound are excluded

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39
Q

What is the main drug binding protein?

A

Albumin

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40
Q

How are drugs attached to albumin affected?

A

Cannot leave blood
Increases drugs half-life

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41
Q

Why do drugs enter cells

A

Some to reach site of action.

All drugs must enter for metabolism and excretion.

42
Q

How do drugs cross the cell membrane?

A

(1) Either lipid-soluble
(2) able to activate a transport system

43
Q

Define Metabolism

A

chemical alteration of drug structure

44
Q

Where does most drug metabolism occur

A

Liver

45
Q

What enzyme is most drug liver metabolism performed by

A

hepatic microsomal enzyme system P450 (CYP)

46
Q

Therapeutic Consequence of Drug Metabolism

  • what can happen when the liver metabolizes a drug
A

(1) Promotion of renal excretion of drugs
(2) Drug Inactivation
(3) Increased effectiveness of drug
(4) Activation of prodrugs
(5) Increased/ decreased toxicity

47
Q

Most Important consequence of metabolism

A

promotion of renal drug excretion

48
Q

How does the liver excrete highly lipid soluble drugs

A

Converts into hydrophilic drugs

49
Q

How does liver convert lipid-soluble drugs to hydrophilic drugs?

A

(1) Structural change –> less lipid soluble
(2) Glucuronidation= lipophilic converted to hydrophilic

50
Q

What is a Prodrug?

A

a compound pharmacologically inactive when administered but is converted to active form via metabolism

51
Q

Toxicity

A

Converting drugs into inactive forms

52
Q

How does age affect Drug metabolism?

A

Infants- limited metabolism, liver not fully developed until 1
Older adults- decreased metabolism

53
Q

p450 substrates

A

drugs that are metabolized by P450

54
Q

P450 inducers

A

Drugs that cause liver to increase drug metabolism

55
Q

P450 Inhibitor

A

drugs that cause liver to decrease drug metabolism

56
Q

First Pass Effect

A

rapid hepatic inactivation of oral drugs
- these drugs are generally administered parenterally

57
Q

Drug Competition

A

if 2 drugs are metabolized by the same pathway, one or both will have their metabolic rate depressed.

58
Q

Enterohepatic recirculation

A

drugs in GI tract carried through portal vein to liver. Liver excretes bile containing drug back to GI tract. Continuous this path indefinitely.

59
Q

Excretion

A

Removal of drugs from body

60
Q

How are drugs excreted from the body?

A

urine, sweat, saliva, breast milk, expired air

61
Q

Most important organ for drug excretion

A

Kidney

62
Q

What organ limits the duration of drug action. and why?

A

Kidneys
They account for the excretion of most drugs

63
Q

Steps in Renal Drug Excretion

A

(A) Glomerular filtration
(B) Passive Reabsorption
(3) Active Secretion

64
Q

Glomerular Filtration

A

Moves drugs from blood to urine.

65
Q

What is a limitation of Glomerular Filtration

A

Cannot remove drugs bound to albumin

66
Q

What occurs during passive reabsorption in kidneys

A

PH in tubule is higher than in blood.
Concentration gradient occurs.
Lipophilic drugs reabsorb PASSIVELY back into blood.
Non-lipid-soluble drugs remain to be excreted.

66
Q

what happens to many lipophilic drugs during metabolism?

A

liver converts to hydrophilic molecules using Glucuronidation

66
Q

How does the liver convert lipophilic drugs into hydrophilic molecules?

A

Glucuronidation

67
Q

What is active tubular secretion

A

active transport that pump drugs from blood into tubular

68
Q

What are the two primary pumps in active tubular secretion?

A

(1) for organic acids
(2) for organic bases

69
Q

What do PGP cells do in renal drug extraction? Location

A

located in tubular cells-
Pump drugs from blood into tubular lumen

70
Q

What plays a significant role in excretion of drugs in kidneys

A

PGP pumps

71
Q

pH dependent ionization in kidneys

A

increases renal drug excretement by
-causing passively secreted lipid-soluble drugs to be ionized and
-then they cannot leave the renal tubular and is excreted.

72
Q

Explain how Aspirin poisoning is treated

A

an agent is given to make urine pH basic (higher ph)
Aspirin is an acid.
The basic urine ionizes the aspirin
Ionized aspirin molecules are excreted in urine

73
Q

What processes are used to convert lipid- soluble drugs for excretion?

A

(1) Glucuronidation
- lipophilic into hydrophilic

(2) Kidney performs pH dependent ionization
- ionization decreases passive reabsorption

74
Q

Nonrenal excretion

A

Breastmilk
- lipophilic drugs access to breast milk

Bile
- enterohepatic recirculation

Lungs
- volatile anesthetic are excreted

75
Q

What determines how much drug will be available at site of action

A

absorption, distribution, metabolism, and excretion

76
Q

what are ADME major determinants of

A

(1) Time drug response starts
(2) Time drug will be MONST INTENSE
(3) Time drugs action will CEASE

77
Q

What are the sections of Time Course of Drug Responses

A

(1) Plasma drug levels
(2) single- dose time course
(3) drug half- life
(4) drug levels with repeated doses

78
Q

Time course of drug action has a direct relationship to

A

drug in blood

79
Q

What are the two very important drug levels?

A

(1) Minimal effective concentration
(2) Toxic concentration

80
Q

What is the minimal effective concentration

A

the threshold of where therapeutic effects occur

81
Q

What is toxic concentration?

A

level where toxic effects begin
-Doses should not reach this level

82
Q

Therapeutic Range

A

range between minimum effective concentration and toxic concentration.

83
Q

What does a narrow therapeutic range indicate

A

drug is difficult to administer safely
-narrow concentration more dangerous than wide

84
Q

Give example of narrow therapeutic concentration and wide TC

A

narrow- lithium
wide - acetaminophen

85
Q

Single- dose time course

A
  • plasma drug levels change over time
86
Q

What is the latent period

A

the time between the drug is administered and the onset of effects

87
Q

What determines the extent of the Latent period after administration of dose

A

determined by the rate od absorption

88
Q

What is the duration of effect determined by

A

Metabolism and Excretion

89
Q

drug half-life

A

time required for amount of drug in body to decrease by 50%
- no matter what amount of the drug half of it will leave during a specified time

90
Q

How does half-life determine dosing interval

A

Short half-life = shorter interval
long half- life = longer interval

91
Q

What is drug accumulation

A

when multiple doses are given and the amount in the body continues to accumulate

92
Q

Plaeau drug levels

A

where the maximum amount of drug is accumulated in the body from any subsequent doses

93
Q

Steady State

A

where the drug eliminated is equal to drug amount administered

94
Q

how long for plateau to be reached if administered repeatedly at the same dose

A

4 half lives

95
Q

how to reduce fluctuation in drug levels

A

(1) administer by continuous infusion

(2) administer a depot preparation- releases drug slowly and steadily

(3) reduce both dose size and dosing interval

96
Q

Depot preparation

A

releases slowly over time

97
Q

Loading doses

A

large initial dose given to achieve plateau in less weeks with a drug that has a long half life

98
Q

Maintenance doses

A

the doses given after a loading dose to maintain plateau

99
Q

How long does it take for MOST (94%) of a drug to be eliminated?

A

4 Half-Lives

HLSC 222- midterm 1 (10 decks)

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