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HLSC 220 Pharmacotherapeutics for Health Professionals 💊 > Principles of Pharmacology- Ch 4-5 > Flashcards

Principles of Pharmacology- Ch 4-5 Flashcards

1
Q

What are the 2 branches of pharmacology?

A

Pharmacokinetics
Pharmacodynamics

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2
Q

What is Pharmacokinetics?

A

Branch that describes what the body does to the drug and how the drug concentration in the plasma changes over time

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3
Q

What is Pharmacodynamics?

A

Branch that describes what the drug does to the body, the relationship between drug concentration and effect

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4
Q

What are the 4 stages of Pharmacokinetics divided into?

A

ADME

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5
Q

What does ADME stand for?

A

Absorption from site of admin
Distribution within the body
Metabolism
Excretion

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6
Q

Why is it important to understand the differences between routes and formulations for drug administration?

A

Because different adminatration methods affect how quickly and how much drug enters the systemic circulation

important in determining the peak plasma concentration, action duration

chosen route for a drug depends on desired outcome

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7
Q

Are all administration routes suitable for all drugs?

A

No

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8
Q

What does adminstration of drug formulations depend on?

A

-Route of administration
-Time-course of action
-Active drug concentration

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9
Q

What are the 3 main types of administartion?

A

Enteral
Parenteral
Topical

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10
Q

What is Enteral administration?

A

Entry of drug through the Gastrointestinal (GI) tract
-Absorption occurs somewhere between mouth and anus

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11
Q

What is Parenteral Administration?

A

Not by GI tract

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12
Q

What is Topical administration?

A

Drug is administered by the skin/mucous membrane
-Ointment, creams

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13
Q

What is Oral enteral administration?

A

Results in drug absorption through the stomach or small intestine

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14
Q

What is oral enteral absorption?

A

<100%

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15
Q

What does oral enteral absorption depend on?

A

-Solubility
-GI tract acidity
-Stability of drug (does acid/digestive enzymes destroy it?)
-Gastric emptying/motility
-GI blood flow

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16
Q

What are the benefits of Oral (PO) administration?

A

Easiest, safest and cheapest
No need for drug to be sterile or pure

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17
Q

What are the drawbacks of Oral (PO) administration?

A

-Acid-sensitive and protein drugs are unstable
-Patient must be conscious and cooperative
-Variable absorption and bioavailability
-Possible upper GI tract irritation

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18
Q

Where do most drugs given orally pass through before entering systemic circulation?

A

The liver
-Major site of drug metabolism

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19
Q

What is the name of the effect of orally given drugs dropping in concentration during liver metabolism?

A

First Pass Metabolism
or Pre-systemic elimination

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20
Q

Are all drugs extensively metabolized by the liver?

A

No drug metabolism is drug-to-drug dependent
-Some are very metabolized, some are not metabolized

e.g, Drug A: 100% dose taken —liver–> 100% of dose enters blood

e.g, Drug B: 100% dose taken —Gut wall–> 70% of dose —Liver–> 15% of dose enters blood

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21
Q

What is Rectal (Pr) enteral administration?

A

Absorption is through the rectal mucosa

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22
Q

What are the benefits of Rectal (Pr) enteral administration?

A

Rapid absorption
Cheap, easy
Useful when patients can’t/won’t swallow
Less first pass effect

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23
Q

Why is there less first pass effect when drugs are given via Rectal (Pr) enteral administration?

A

Fewer rectal veins enter the liver

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24
Q

What are the drawbacks of Rectal (Pr) enteral administration?

A

Absorption often incomplete
Many drugs irritate mucosal lining

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25
Q

What is Sublingual (SL) Enteral administration?

A

Drugs placed under the tongue

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26
Q

What are the drawback of Sublingual (SL) Enteral administration?

A

Many drugs taste bad

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27
Q

What are the benefits of Sublingual (SL) Enteral administration?

A

Rapid absorption
No first pass effect
Suitable for acid-senstive drugs (mouth pH= 7)
Fast, easy, cheap

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28
Q

Why is there no first pass effect when Sublingual (SL) Enteral administration?

A

It allows for direct entry into systemic circulation

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29
Q

What pharmacokinetic profiles are Sublingual administration similar to?

A

SC, IM and IV administration

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30
Q

Why is SL administration similar to SC, IM and IV administration pharmacokinetically?

A

Drug crosses mucosa into systemic circulation
-no first pass

Bioavailability very high and consistent

Bypass stomach and intestine environment

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31
Q

What are the formulations of enteral administration?

A

Tablets
Caplets
Capsules
Liquids
Buccal film

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32
Q

What are capsules?

A

Powder in a gelatin coating
-Allows faster absorption

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33
Q

What are liquids formulations?

A

Aqueous (dissolved in water)
Suspensions or emulsions
-Even faster absorption

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34
Q

What are buccal films?

A

Drug absorbed between gum and cheek

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35
Q

What is parenteral administration subcutaneous injection?

A

Drug is injected under the skin

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36
Q

What are the benefits of subcutaneous injection (SC)?

A

Rapid effect via general circulation
Useful for local drug delivery (e.g, local anesthetics)
Easy self-administration

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37
Q

Can subcutaneous drug absorption into circulation be controlled?

A

It may be controlled
e.g, Vasoconstricting agents

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38
Q

What are the drawbacks of subcutaneous injection (SC)?

A

Requires sterile drug
Some patents do not like injections
Absorption greatly affected by blood flow and injection volume

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39
Q

What is parenteral administration of Intramuscular injection (IM)?

A

Drug injected into skeletal muscle

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40
Q

What are the benefits of intramuscular injection (IM)?

A

Can be into a large muscle mass
Self-administration

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41
Q

Can intramuscular drug absorption into circulation be controlled?

A

It may be controlled
e.g, Oil-based formulations allow slower absorption
-‘depot’ bolus (inject a drug and it can last for weeks)

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42
Q

What are the drawbacks of intramuscular injection (IM)?

A

Can be painful

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43
Q

What is parenteral administration intravenous (IV)?

A

Drug injected directly into vein either as rapid bolus (IV push) or as continuous infusion (IV drip)

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44
Q

What are the benefits of IV administration?

A

All of drug enters bloodstream (100% bioavailability)
Rapid distribution and onset of action
Large drug volumes

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45
Q

WHat are the drawback of IV administration?

A

Requires skilled administration and close monitoring
Drug must be sterile
Greater cost

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46
Q

What is another route of drug administration?

A

Inhalation

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47
Q

What is inhalation administration?

A

Drug inhaled into airways

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48
Q

What are the benefits of inhalation?

A

Useful for local action (e.g, Bronchodilators) but can alsp be absorbed into pulmonary circulation
No first-pass effect
Useful for gasses

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49
Q

What are the drawbacks of inhalation?

A

Limited absorption of large proteins
Possible irritation of lung lining

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50
Q

What formulations are used for inhalation?

A

Gasses or gas mixtures
Inhalers for pulmonary use
Pressurized aerosol

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51
Q

When are inhalers used?

A

Particulate powders
Nebulized (mist)

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52
Q

What do pressurized aerosols and other containers allow for?

A

Unused products to remain uncontaminated for later use

53
Q

In summary what are all the enteral administration methods?

A

Oral (PO)
Rectal (pr)
Sublingual (SL)

54
Q

In summary, what are all the parenteral administration methods?

A

Subcutaneous Injection (SC)
Intramuscular Injection (IM)
Intraveous (IV)

Intra-articular injection (Joints)
Intra-cardiac injection (heart)
Epidural injection
Spinal injection (into spinal fluid)

55
Q

Whata re the topical administration routes?

A

Skin
Eyes (drops - gtt; ointment)
Ears
Nose
Vagina

56
Q

What is Transdermal topical administration?

A

Absorption through skin for local effects and systemic effects

57
Q

What are the benefits of Transdermal topical routes?

A

Cheap, easy
Simple local administration
no first pass effect

58
Q

What are the drawbacks of transdermal topical routes?

A

Not suitable for many drugs e.g, fat insoluble
Absorption affected by skin hydration

59
Q

What are some formulations used for transdermal topical administration?

A

Creams, gels, ointment
Suspension in an oily vehicle (enhances absorption)
Controlled-release patches (e.g, nicotine)
Topical aerosol spray

60
Q

What is drug absorption?

A

Entry of drug into the circulatory system

61
Q

Example of drug absorption?

A

Orally administered drugs
-Pass through epithelial cells of the GI tract then into blood flowing through capillaries of GI wall

62
Q

What chemical factors affect drug absorption?

A

Drug size
Lipid solubility
Drug charge

63
Q

Bioavailability

A

The proportion of drug that passes into the systemic circulation after administration.
-Takes into account both absorption and local metabolic degradation

64
Q

Is bioavailability high or low with PO administration?

A

Low
-Often much less than 100% if po

65
Q

Is bioavailability high or low with SC, IM and IV administration?

A

High

66
Q

What affects bioavailability?

A

First-pass effect
Drug absorption
(Solubility, stability and formulation of the drug)

67
Q

What is Drug distribution?

A

After absorption, the drug is mixed throughout the blood very quickly
-Average time for blood circulation is ~1 minute

68
Q

What does the initial rapid distribution of a drug depend almost entirely on?

A

Rate of blood flow to a given tissue

e.g, tissues with a high blood flow will be exposed to more drug, more quickly, than those with low blood flow

69
Q

Examples of tissues with rapid distribution?

A

Heart, liver, kidneys, brain

70
Q

Examples of tissues with slow distribution?

A

Muscle, skin, fat

71
Q

What does the second slower phase of distribution depend on?

A

Where a drug ‘likes’ to be
-Can take minutes to hours

72
Q

What factors affect second, slower phase of distribution?

A

Lean mass (watery environment e.g, muscle)
Fat solubility of the drug - drug accumulation
Plasma binding protein

73
Q

In general, what three factors determine drug distribution?

A

Blood flow distribution
Exiting the vascular system
Entering cells

74
Q

Do most drug molecules float around within blood?

A

No drugs are often bound to a plasma protein (Plasma protein binding)
The % of a drug bound to protein can be quite high (90% of more, slows distribution)

75
Q

What is the most common plasma protein and major carrier of drugs?

A

Albumin

76
Q

What happens to someone with liver disease in regards to plasma protein binding?

A

The liver makes albumin, therefore diseased liver = decreased albumin —> Increased free drugs (rapid distribution, unpredictable)

77
Q

How does our body get rid of drugs?

A

Metabolism
Excretion

78
Q

Metabolism

A

Modification (change) of drug molecule by cell enzymes

79
Q

Excretion

A

Removal from body

80
Q

Where does most drug metabolism occur?

A

Mostly in liver
-Also occurs in the gut, kidney, lungs, plasma and placenta

81
Q

What family of enzymes are drugs largely metabolized by?

A

Cytochrome P450

82
Q

How are the Cytochrompe P450 enzymes identified?

A

Cytochrome P450 family. Family. Subfamily. Isoform
e.g, CYP2D6
[CYP= Cytochrome P450 family] [2= Family] [D= Subfamily] [6= isoform]

83
Q

What are the therapeutic consequences of drug metabolism?

A

Accelerated renal drug excretion
Drug inactivation
Increased therapeutic action
Activation of prodrugs
Increased or decreased toxicity

84
Q

What is the most common therapeutic effect/consequence of drug metabolism?

A

Accelerated renal drug excretion
-Aids water solubility

85
Q

Do all drugs metabolise the same in every indivdual?

A

No there is variation between individuals

86
Q

Doing what to CYPs can be dangerous?

A

Inhibition

87
Q

What inhibits CYPs?

A

Grapefruit juice
Other drugs (competition)

88
Q

What is CYP enzyme induction?

A

Cells stimulated to make more enzymes

89
Q

Where does most drug excretion occur?

A

Through the kidney

90
Q

What other places does drug excretion occur?

A

GI tract (including via bile)
Sweat
Breast milk

91
Q

What does drug excretion depend on?

A

Plasma protein binding
Drug fat solubility/charge

92
Q

What is the filtration unit of the kidney?

A

Nephrons
-each kidney contains about 1 million

93
Q

How do drugs enter tubular fluid?

A

Filtration through glomerular capillaries (blood to urine)
Active transport through specialized carriers

94
Q

Are some drugs able to be excreted in an unaltered form?

A

Yes
e.g, some antibiotics

95
Q

Most drugs must undergo what process first before excreteion?

A

Metabolism

96
Q

What does metabolism do to a drug before it is excreted?

A

renders it inactive
Makes the drug more water soluble/less fat soluble

97
Q

Effective treatment requires…?

A

Optimal dosage regime
-Dose size and frequency

98
Q

What largely determines the duration of the effects of a drug?

A

Metabolism and excretion

99
Q

What is a drug steady state?

A

When there is a consistent level of drug in the body
- Drug accumulates in the body until the amount being administered equals the amount being eliminated.

100
Q

What is the half-life of a drug (T 1/2)?

A

The time required for the amount of drug in the body to decrease by 50%
Measure of the rate at which drugs are removed from the body

101
Q

The time to reach a steady state depends on what?

A

The drug’s half-life (T 1/2)
Steady-state reach in 4-5 T1/2
Drug entry = drug exit

102
Q

If a drug has a long T1/2?

A

It takes a long time to reach a steady state (with repeated dosing)

103
Q

If a drug has a short T1/2?

A

It takes a short time to reach a steady state (with repeated dosing)

104
Q

Explain morphine’s steady state

A

Morphine T 1/2 = 4hours
~18 hours needed to reach a steady state

105
Q

Explain Digoxin’s steady state

A

Digoxin T 1/2= 36hours
~7 days to reach a steady state

106
Q

What are most drugs metabolized/excreted according to?

A

Principles of percentage loss of drug over time
-NOT a fixed amount

107
Q

Do any drugs leave the body at a constant rate?

A

A few leave the body at a constant rate
e.g, 10 mg in 3 hours regardless of how much is present

108
Q

Examples of drugs that leave the body at a constant rate?

A

Ethanol (alcohol)
Phenytoin (epilepsy drug)

109
Q

What is usually required for drugs to elicit an effect on the body?

A

They must interact directly with cells (bind to receptors)

110
Q

What are drug receptors?

A

Protein targets, or sometimes DNA (some anti-tumour drugs) and cell membranes (some antimicrobial agents)

111
Q

What should drugs exhibit for their receptor?

A

Selectivity
-Interact only with their target molecule, cell or tissue

112
Q

What might drugs lose at high concentrations?

A

Selectivity

113
Q

What are the 2 common possibilities of drug action?

A

Drug A + Receptor —> Drug A-receptor —> Response
(Agonist)

Drug B + Receptor —> Drug B-receptor —> NO response
(Antagonist)

114
Q

What does binding of a drug depend on?

A

Affinity of drug for its target

115
Q

Affinity

A

‘Stickiness’
The degree to which a substance tends to combine with another.

116
Q

What is an Agonist?

A

Elicits a response

117
Q

What is an Antagonist?

A

Prevents a response to endogenous agonist

118
Q

What are Dose-response relationships?

A

Relationship between the size of an administered dose and the intensity of the response produced

119
Q

What do Dose-Response Relationships determine?

A

-Minimum amount od drug to be used
-Maximum response of a drug can elicit
-How much to increase the dosage to produce the desired increase in response

120
Q

Onset

A

The time it takes for the drug to elicit a therapeutic response

121
Q

Peak

A

Time it takes for a drug to reach its maximum therapeutic response

122
Q

Trough

A

Lowest blood level
-If too low the drug is ineffective

123
Q

Minimum Effective Concentration (MEC)

A

Plasma drug level that must be reached for a therapeutic effect

124
Q

Duration

A

Time for which a drug concentration is sufficient to elicit a therapeutic response

125
Q

Therapeutic Index

A

Measure of a drug’s safety
Ratio of the amount at which a drug’s toxic : Amount at which drug is effective

126
Q

A drug with a larger therapeutic index is ______?

A

Safer

127
Q

A drug with a smaller therapeutic index is ____ _____?

A

Less safe
-Called NTI’s (Narrow Therapeutic Index drugs)

128
Q

Describe the responses of Non-receptor drugs

A

Simple physical or chemical interactions with other small molecules

129
Q

Examples of receptorless drugs

A

Antacids
Saline laxatives
Chelating agents

HLSC 220 Pharmacotherapeutics for Health Professionals 💊 (15 decks)

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