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Pharmacology Test #1 > Pharmacodynamics > Flashcards

Pharmacodynamics Flashcards

1
Q

Concentration of a drug at the site of action is dependent on

A

rate of absorption and blood flow to the site

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2
Q

how long a drug remains at the site in effective concentrations depends on

A

biotransformation (metabolism) and excretion

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3
Q

sites of drug action

A

extracellular
intracellular
on the cell surface

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4
Q

intracellular sites

A

drugs used to treat infections
drugs used for cancer chemotherapy
hormones such as estrogen

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5
Q

EC 50

A

way to measure the potency of a drug

drug concentration at which the drug is 50% effective

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6
Q

law of mass action

A

the effect of a drug is directly proportional to the amount of drug-receptor complex formed

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7
Q

rate of association

A

k1 [D][R]

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8
Q

rate of dissociation

A

k-1 [DR]

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9
Q

rate at equilibrium

A

rate of association is equal to the rate of dissociation

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10
Q

the lower the Kd?

A

the higher the affinity

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11
Q

Kd?

A

half of the receptors are bound by the drug

measure of affinity

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12
Q

assumptions made for the law of mass action

A
  1. the binding is totally reversible
  2. D and R only exist as free and bound
  3. all receptor sites are considered to have equivalent affinity for D and to be independent
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13
Q

Potency

A

the dose of a drug required to produce a particular effect of given intensity (comparison based on doses that produce the same effect)

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14
Q

Affinity

A

the ability of the drug to interact with the receptor

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15
Q

What does a strong agonist have?

A

high affinity and high efficacy

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16
Q

Maximal efficacy is often limited by?

A

toxicity

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17
Q

What is more important, efficacy or potency?

A

Efficacy

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18
Q

partial agonist

A

produces a reduced response even at full receptor occupancy

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19
Q

Receptor antagonist

A

a drug-receptor interaction that interferes with or prevents the development of a drug response by an agonist

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20
Q

three major types of receptor antagonists

A
  1. competitive
  2. mixed
  3. irreversible
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21
Q

How can you reverse a competitive antagonist?

A

increasing the dose of the agonist

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22
Q

describe the log dose-response curve for an agonist in the presence of a competitive antagonist

A

shifted to the right indicating a reduction in the effective potency of the agonist

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23
Q

shape of the log dose-response curve with a competitive antagonist

A

shape and maximal response are not altered

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24
Q

Noncompetitive antagonist

A

the antagonist produces its effect at a site of the receptor other than the site used by the agonist

25
increasing noncompetitive antagonist concentrations do what to Kd and Emax?
increase Kd and decrease Emax of the agonist
26
describe the log dose-response curve in the presence of a noncompetitive antagonist?
shifted to the right the slope of the agonist curve and maximal response obtained are progressively decreased at very high concentrations of antagonist, no amount of agonist can produce a response
27
Describe the log dose-response curve in the presence of a noncompetitive antagonist.
shifted to the right the slope of the agonist curve and maximal response obtained are progressively decreased at very high concentrations of antagonist, no amount of agonist can produce a response
28
Describe the log dose-response curve in the presence of an irreversible antagonist.
initially the dose-response curve is shifted to the right (resembles competitive) as antagonist concentration is increased, maximal response obtained is progressively decreased (resembles noncompetitive inhibition)
29
functional (physiological) antagonist
two drugs influence a physiological system but in opposite directions each drug is unhindered in the ability to elicit its own characteristic response
30
chemical antagonism
a chemical reaction occurs between an agonist and an antagonist to form an inactive product
31
intracellular receptors
stimulate the transcription of genes in the nucleus by binding to specific DNA sequences near the gene whose expression is to be regulated
32
therapeutic significance of intracellular receptors
drugs produce their effects after a characteristic lag period effects can persist after the agonist concentration has been reduced to zero
33
kinase
enzyme which adds a phosphate group to a substrate
34
describe protein tyrosine kinases
receptor consists of an extracellular hormone-binding domain and a cytoplasmic enzyme domain with protein tyrosine kinase activity (spans the membrane once)
35
protein tyrosine kinases usually act as
dimers
36
How do ligand-gated channels work?
following ligand binding, the signal is transmitted across the plasma membrane by increasing transmembrane conductance of the relevant ion. Alters the electrical potential across the membrane.
37
How do ligand-gated channels work?
Following ligand binding, the signal is transmitted across the plasma membrane by increasing transmembrane conductance of the relevant ion. Alters the electrical potential across the membrane.
38
Types of receptors
1. intracellular receptors 2. protein tyrosine kinases 3. ion channels 4. GPCRs
39
examples of second messengers
1. cyclic AMP 2. calcium ion 3. phosphoinositides
40
cAMP
effector enzyme is adenylyl cyclase and the enzyme converts ATP to cAMP stimulates cAMP-dependent protein kinases
41
calcium and phosphoinositides
effector enzyme is phospholipase C | results in the release of phosphoinositides and diacylglycerol
42
cGMP
effector enzyme is guanyl cyclase | activates cGMP-dependent protein kinase
43
Assumptions for quantal log-dose reponse relationships
At the dose given, the subject will respond to the maximum, or not at all
44
threshold
the minimum effective dose of the drug which evokes an all-or-none pharmacological response
45
normal frequency distribution
doses required to produce a specified quantal effect are log-normally distribulated
46
median effective dose (ED50)
the dose required to produce the stated effect in 50% of the population
47
median lethal dose (LD50) or | median toxic dose (TD50)
dose required to produce death in 50% of the population or a particular toxic effect in 50% of the population
48
Therapeutic index or Ratio
the relative safety of a drug expressed as LD50/ED50 | larger the ratio the greater the relative safety
49
Graded log-dose response relationships
the responding system is capable of showing progressively increasing effects with increasing concentrations of the drug
50
drug tolerance
condition of decreased responsiveness to a drug
51
development of drug tolerance
1. decrease in effective concentration of the agonist at the site of action 2. decrease in the normal reactivity of the receptor
52
Cross tolerance
tolerance develops to one drug that is also seen with drugs belonging to the same class
53
tachyphylaxis
acute development of tolerance following rapid, repeated administration of a drug (ex. ephedrine)
54
drug allergy
an adverse response to a foreign chemical resulting from previous exposure to the substance
55
Type I hypersensitivity
first exposure causes IgE to the produced rapid onset symptoms may be localized or systemic
56
Type II hypersensitivity
antibody-dependent cytolytic reaction IgG and IgM antibodies produced antibodies activate the complement system subsides within months after removal of drug
57
Type III hypersensitivity
Immune complex formation drug reacts in blood with soluble antibody (IgG) resulting immune complex deposited in vascular endothelium serum sickness, hemolysis and allergic nephritis subsides 1-2 weeks after drug is removed
58
Type IV hypersensitivity
delayed hypersensitivity hours or days after exposure mediated by antigen contact with T lymphocyte contact dermatitis with topic drugs
59
Idiosyncratic reaction
a genetically determined abnormal reactivity to a drug

Pharmacology Test #1 (5 decks)

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