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Clinical Foundations > Pharmacology > Flashcards

Pharmacology Flashcards

1
Q

Pharmacodynamics

A

Biochemical and physiological mechanisms of drug actions and relate to molecular interactions between body constituents and drugs
Effect of drugs based on the concept of drug receptor interactions in order to determine efficacy, potency and toxicity

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2
Q

Maximal efficacy

Emax

A

Largest effect that a drug can produce

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3
Q

ED50

A

Dose of drug required to produce a defined therapeutic effect in 50% of the population receiving drug

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4
Q

LD50

A

The dose that is lethal in 50% of animals treated

Demonstration of adverse drug responses.

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5
Q

Therapeutic index

TI

A

Ratio of LD50/ED50

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6
Q

Efficacy

A

Effectiveness.
Aspirin vs morphine.
Same ED50 but efficacy different at same dose.

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7
Q

Potency

A

Dosing difference. Efficacy is same.

Morphine vs meperidine.

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8
Q

LD50

A

Dose of drugs that produce adverse response.

Extent. Of drugs effect due to increase dose or idiosyncratic responses.

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9
Q

Therapeutic Index

A

Relative safetiness. Usually between 2 drugs.

LD50/ED50

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10
Q

Ligand

A

Agonist or antagonist chemical/dru that binds to a receptor

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11
Q

Receptor

A

Target/site of drug action

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12
Q

Affinity

A

Propensity/attraction of a drug to bind with a receptor

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13
Q

Selectivity

A

Specific affinity for certain receptors vs other receptors.

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14
Q

Agonist

A

Chemical that binds to a receptor and activates the receptor to produce a biological response

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15
Q

Antagonist

A

Blocks the action of the agonist at the same receptor.

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16
Q

Pharmacological agonists

A

Mimic actions of endogenous neurotransmitters at same site

Demonstrate high affinity binding and activate receptors with good specificity

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17
Q

Pharmacological antagonists

A

Block actions of neurotransmitter at same site
Competitive vs non competitive
Partial vs inverse

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18
Q

Competitive antagonists

A

Reduce potency of agonists but have no effect on overall efficacy. Their effects are able to be overcome by increasing concentration of agonist substrate concentration

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19
Q

Non competitive antagonist

A

Reduce agonist efficacy and their effects are not overcome by increasing agonist substrate concentration

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20
Q

Partial agonist

A

Act at same site as the full agonist but with lower maximal efficacy

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21
Q

Inverse agonist

A

Causes an action opposite to that of the agonist at same receptor

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22
Q

Physiological antagonists

A

Activate physiological responses that oppose agonist mediated physiological responses.

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23
Q

Enzyme receptor

A

Receptor is linked to kinase which leads to series of phosphorylation reactions
Insulin receptor

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24
Q

Ligand gated ion channel

A

Ligands bind to receptor which causes channel to open allowing ions to pass in/out of cell
Nicotinic acetylcholine receptor

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25
Q

G protein coupled receptor

A

Receptor is linked to family of G proteins which then cause biological response through secondary messenger systems
CAMP

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26
Q

Transcription factor

A

Receptor is intracellular and activation/inhibition affects gene transcription

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27
Q

Specificity

A

Alterations to drug’s chemical structure may influence potency
Many drugs have multiple sites of action resulting in side effects

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28
Q

Sensitivity

Upregulation

A

Presence of antagonist causes increased celllular build up of receptors.
Removal of antagonist produces increase physiological response to agonist due to increased receptor population

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29
Q

Tolerance

Down regulation

A

Long term exposure to an agonist reduces receptor population or receptor responsiveness thus reducing physiological response.

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30
Q

Additive

A

Effect of sub x and y together is equal to sum of ind effects
Aspirin and acetaminophen

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31
Q

Synergistic

A

Effect of sub x and sub y is greater than sum of ind effects

Clopidogrel with aspirin

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32
Q

Tachyphylaxis

A

Decreased drug response by many potential mechanisms
Acute decrease in response to drug after initial/repeat administration
Morphine

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33
Q

Pharmacokinetics

A

Study of how the body impacts the drug
Absorbed
Distributed
Eliminated

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34
Q

Standard drug dose

A

Based on trials in healthy individuals with average physicological processes.

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35
Q

Pharmacokinetics can be effected by

A

Age
Liver funciton
Renal function
Fat/lean tissue

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36
Q

What molecules can cross the cell membrane

A

Nonpolar molecules such as steroids cross easily

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37
Q

How do large polar molecules may enter cell through

A

Protein pores/channels

Facilitated / active carriers

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38
Q

Many drugs don’t need to enter cell but act where

A

At cell surface receptors via second messengers

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39
Q

Drug diffusion

A

Drugs able to enter cell do so through diffusion

Movement of these drugs is based upon Fick’s law.

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40
Q

Effect of charge on diffusion

A

Presence of charge will impede drug’s ability to cross cell membrane
Uncharged molecules are readily lipid soluble
Charged molecules are readily water soluble

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41
Q

Ph/ion trapping principle

Pka vs ph

A

Pka ph - uncharged drug form

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42
Q

Example of ph/ion trapping

A

Example of drug with Pka =4.4
Unchargedd drug diffuses through lipid bilayer at pH1.4
Charged drug is trapped in blood at pH 7.4

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43
Q

Acidic urine favors excretion of

A

Weak bases

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44
Q

Alkaline urine favors excretion of

A

Weak acids

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45
Q

Why can’t drugs pass into the BBB

A

Capillaries contain specialized tight junctions that prevent passive diffusion of most drugs

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46
Q

What sort of drugs act on the CNS

A

Must be hydrophobic.

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47
Q

Intrathecal administration

And function

A

Drug is injected directly into the CSF as way to bypass BBB

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48
Q

Absorption areas

A 
Uptake of drug from
GI tract- enteral 
Tissue/muscle - parenteral 
Mucous membranes
Skin - transdermal
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49
Q

Enteral advantages

A 
Simple
Inexpensive
Convenient
Painless
No infection
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50
Q

Enteral disadvantages

A

Drug exposed to harshGI environments
First pass metabolism
Requires GI absorption
Slow delivery to action site

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51
Q

Parenteral advantages

A

Rapid delivery to site of pharmacological action
High bioavailability
Skips 1st pass

52
Q

Parenteral disadvantages

A

Irreversible
Infection
Pain

53
Q

Mucous membrane advantages

A

Rapid delivery to action site.
Skips 1st pass
Usually painless
Low infection

54
Q

Mucous membranes disadvantages

A

Few drugs have chemical characteristics/formulations that allow them to be administered this route.

55
Q

Transdermal advantages

A 
Simple
Convenient
Painless
Excellent for continuous/prolonged administration
Skips 1st pass
56
Q

Transdermal disadvantages

A

Requires highly lipophilic drug
Slow delivery to site
May be irritating

57
Q

Subcutaneous advantages

A

Slow onset

May be used to administer oil based drugs

58
Q

Subcutaneous disadvantages

A

Slow onset

Small volumes

59
Q

Intramuscular advantages

A

Intermediate onset

May be used to administer oil based drug

60
Q

Intramuscular disadvantages

A

Can affect lab tests CK
Intramuscular hemorrhage
Painful

61
Q

Intravenous advantages

A

Rapid onset

Controlled drug delivery

62
Q

Intravenous disadvantages

A

Peak related drug toxicity

63
Q

Intrathecal advantages

A

Bypasses BBB

64
Q

Intrathecal disadvantages

A

Infection

Highly skilled personnel required

65
Q

First pass metabolism

A

Oral drugs only
Drugs absorbed from GI are carried to liver via hepatic portal vein
May reduce amount of drug reaching target tissue by inactivating drug
Some cases results in activation of inert prodrug

66
Q

Bioavailability

A

Fraction of unchanged drug reaching systemic circulation following administration by any route.

67
Q

Bioavailability equation

A

Quantity of drug reaching systemic circulation / quantity of drug administered

68
Q

Factors that affect bioavailability

A

Extent of absorption

First pass metabolism

69
Q

Bioavailability of 100%

A

IV

70
Q

Variable bioavailability examples

A

Oral
Rectal
Inhalation
Transdermal

71
Q

Bioequivalence

A

Compare bioavailability of generic drug product to brand name product
Both drug products should contain the same amount of active ingredient.

72
Q

Loading dose

A

Initial dose of drug administered to compensate for distribution into body tissues.

73
Q

Loading dose dependent on

A

Volume of distribution

74
Q

Without a loading dose how many elimination half lives to achieve steady state

A

3-5 elimination half lives

75
Q

Steady state

A

Therapeutic dosing of drug maintained between peak and trough (high and lows)

76
Q

How many half lives does it take to achieve steady state

A

3-5 half lives

77
Q

Maintenance dose

A

Maintains steady state concentration

Subsequent doses needed to replace only amount of drug lost through metabolism and excretion

78
Q

Maintenance dose dependent on what

A

Clearance of drug

Metabolism + excretion / plasma drug concentration

79
Q

Where do water soluble drugs reside

A

Blood

80
Q

Fat soluble drugs reside in

A

Cell membranes
Adipose tissue
Fat rich areas

81
Q

Volume of distribution

A

Represents fluid volume required to contain total amount of absorbed drug in body at uniform concentration equivalent to plasma concentration at steady state.

Amount of drug in body/ plasma drug concentration

82
Q

Drugs with small Vd retained where

A

Primarily retained in vascular compartment

83
Q

Drugs with large vd reside

A

Extensively distributed to tissues (muscle, adipose and other non vascular compartments)
Has long duration of action

84
Q

Vd of about 4L

A

Low
Present mainly in vascular compartment
Heparin

85
Q

Vd about 10 L

A

Medium
Present in extracellular fluid but are unable to penetrate cells
Mannitol

86
Q

Vd of about 42L

A

Medium high
Drugs about to pass most biologic barriers and are distributed in total body water (ICF and ECF)
Alcohol

87
Q

Vd above 42

A

High
Drugs extensively stored within specific cells/ tissues
At low concentration in vascular compartment at steady state
Chloroquine
Azithromycin
Digoxin

88
Q

Rate of accumulation into tissue compartments depends on

A

Blood flow to the organ
Chemistry of the drug
Plasma protein binding of drug

89
Q

Drug protein binding

A

Usually reversible interaction of drugs with proteins in plasma

90
Q

Drug protein bindings

A

Albumin
Alpha 1 acid glycoproteins
Lipoproteins

91
Q

Albumin

A

Most abundant plasma protein

Responsible for most acidic drug binding

92
Q

Alpha 1 acid glycoproteins

A

Responsible for most basic drug binding

93
Q

Lipoproteins

A

Responsible for most lipophilic drug binding

94
Q

Bound drugs

A

Pharmacologically inactive

95
Q

Free unbound drug

A

Can act at target sites and elicit biological response

96
Q

High protein drug binding

A

Leads to more drug present in the central blood compartment and therefore a lower vd.

97
Q

Low protein binding

A

Leads to increased free rug and increased concentration in tissues and therefore results in high vd

98
Q

Disease state or drug and protein binding

A

Disease state or drug can displace highly protein bound drug and increase free drug concentration and may lead to drug toxicity

99
Q

Hypoalbuminemia and protein binding

A

May alter the level of free drug

100
Q

Ceftriaxone and drug protein binding

A

In neonates with hyperbilirubinemia can exacerbate hyperbilirubinermia

101
Q

When would you monitor low clearance drugs with a low therapeutic index

A

When coadministered with drug known to cause displacement interaction

102
Q

Drugs known to cause displacement interactions

A

Warfarin
Phenytoin
Tolbutamide

103
Q

Distribution

Pediatric considerations

A

Drug dosing calculated as mg/kg
Increase total body water and extracellular water, increase vd for hydrophilic drugs
Decrease plasma protein albumin, increase percentage of drug that is active
Decrease body fat, decrease for lipid soluble drugs

104
Q

Distribution

Elderly considerations

A

Age associate changes in body composition can alter drug distribution
Decrease total body water- decrease vd for hydrophilic drugs > higher serum levels.
Increase fat stores increase vd for lipophilic drugs and prolongs half life

105
Q

During acute illness what occurs

A

Decrease plasma protein > increases percentage of unbound drug
Increases alpha 1 acid glycoproteins > increase percentage of unbound drug

106
Q

Where does drug metabolism/biotransformation occur

A

Predominately in liver

Some in other tissues: skin, lungs, GI, and kidneys

107
Q

Endogenous enzyme systems for drug metabolism

A

Cytochrome p450 -95% of oxidative biotransformation
Alcohol dehydrogenase
Monoamine oxidase MAO, amine containing compounds such as catecholamines and tyramine

108
Q

Drug metabolism outcomes

A 
Active drug>inactive metabolite
Unexcretable lipophilic drug> excretable metabolite 
Active drug> active metabolite 
Inactive prodrug>active drug
Active drug> toxic metabolite
109
Q

Metabolism reactions

Functions

A

Aim to reduce lipid solubility (increase hydrophilicity)

Often occur sequentially

110
Q

Phase i reactions

A

Oxidation/reduction/ hydrolysis
Purpose to add polar to make more water soluble metabolites for renal elimination
Mediate by microsomal cytochrome p450.
Phase 1 enzyme activity decreases with patient’s age.

111
Q

Phase ii reactions

A

Conjugation
Purpose to increase polarity to make polar inactive metabolites
Enhances drug’s solubility to be excreted in bile or bile

112
Q

Phase ii conjugation reactions

A

Glucuronidation
Acetylation
Sulfation

113
Q

Cytochrome p450 system

A

Heme protein mono oxygenase
Found in smooth ER of hepatocytes
Metabolizers hydrophobic drugs

114
Q

Cytochrome p450 enzymes important for drug metabolism

A 
Cyp3a4
Cyp2d6
Cyp2c19
Cyp2c9
Cyp2e1
Cyp1a2
115
Q

Genetic variation in cytochrome p450

A

Can alter drug metabolism either by changing the rates of the reactions or eliminating.

116
Q

Pharmacogenetics

A

Study of effects of genetic variability on drug metabolism

117
Q

Rapid metabolizers

A

Ore enzyme present and increased drug metabolism

Induction of enzyme

118
Q

Poor metabolizers

A

Less functional enzyme present and decreased drug metabolism
Inhibition of enzyme

119
Q

Induction of P450 enzyme

A

Increase expression of enzyme, increases drug metabolism and increases drug clearance and decreases drug efficacy

120
Q

Inhibition of p450 enzyme

A

Decrease expression of enzyme, decreases drug metabolism and increases drug toxicity
Competitive or irreversible inhibition by another drug or compound, decreases metabolism

121
Q

Renal excretion

A

Major route of drug excretion

Kidneys receive about 25% total systemic blood flow

122
Q

Rate of drug elimination through kidneys depends upon

A

Balance of
Drug filtered
Drug reabsorbed
Drug secreted

123
Q

Elimination Kinetics first order

A

Constant fraction of drug elimination in unit time
Elimination is proportional to drug
Exponential decay of plasma concentration time curve
Most drugs 95%

124
Q

Zero order elimination kinetics

A

Constant amount of drug elimination in unit time
Elimination saturates at higher
Alcohol, aspirin, warfarin, theophylline

125
Q

half life

A

Amount of time over which the drug concentration in plasma decreases to one half

126
Q

Why is half life important

A

Allows clinician to estimate frequency of dosing required to maintain therapeutic levels

Clinical Foundations (10 decks)

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