Pharmacodynamics

Question 1

Pharmacodynamics

Answer 1

The study of the physiological and biochemical interactions of drug molecules with their target tissues and receptors responsible for their ultimate drug effects.

Question 2

Ligand

Answer 2

any molecule that binds to a receptor

Question 3

Drug

Answer 3

exogenous ligand

Question 4

Neurotransmitters, hormones, peptides

Answer 4

endogenous ligands

Question 5

Receptor

Answer 5

protein molecule on cell surface or within the cell that is the initial site of action of a biological agent

Question 6

receptor examples

Answer 6

neurotransmitters, hormones, peptides, drugs

Question 7

Extracellular receptors

Answer 7

are localized to the cell surface and bind water-soluble ligands (e.g. neurotransmitters)

Question 8

intracellular receptors

Answer 8

bind lipid-soluble ligands within the cell (e.g. steroid hormone receptors)

Question 9

extracellular receptor types are common targets for

Answer 9

psychoactive drugs

Question 10

Ligand-gated ion channels

Answer 10

Postsynaptic neurotransmitter receptors

Question 11

G-protein coupled receptors (GPCR)

Answer 11

Metabotropic receptors
Intracellular second messenger

Question 12

Receptor kinases

Answer 12

Common for cytokine, peptide hormone receptors (e.g. Insulin)

Question 13

intracellular receptor types are common targets for

Answer 13

steroid hormones and lipophilic compounds (and some drugs)

Question 14

intracellular chemicals

Answer 14

Glucocorticoids (stress hormones)
Androgen/estrogens (sex hormones)
Endocannabinoids (intracellular GPCR)

Question 15

Intracellular receptors are located

Answer 15

in cytoplasm

Question 16

Hormone receptors

Answer 16

Translocate to nucleus on hormone binding
Function as transcription factors
Directly induce changes in gene expression by binding to specific response element

Question 17

Agonist

Answer 17

interactions are those that elicit a biological effect on the receptor

Question 18

Antagonist

Answer 18

interactions are those preventing or blocking a biological effect

Question 19

dose-response

Answer 19

With increasing concentration of agonist, the biological response is greater.

Question 20

Potency

Answer 20

ED50 is the dose required to elicit a half-maximal effect.

Question 21

TD50

Answer 21

is a measure of the potency of a drug at eliciting a toxic response.

Question 22

LD50

Answer 22

measures the potency at eliciting a lethal effect.

Question 23

Therapeutic index

Answer 23

reflects the margin of safety between drug efficacy and adverse effects

Question 24

therapeutic index calculation

Answer 24

TI = TD50 / ED50

Question 25

In contrast to agonists, antagonists can be

Answer 25

be reversible or irreversible

Question 26

Reversible antagonists can be displaced by the

Answer 26

endogenous agonist

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Competitive antagonism

Answer 27

Reduces agonist potency but not efficacy

Question 28

Non-competitive antagonists cannot be

Answer 28

displaced by agonists

Question 29

Irreversible antagonists

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Binds irreversibly to the same binding site as an endogenous ligand

Question 30

Non-competitive antagonists Reduce drug

Answer 30

efficacy and sometimes potency

Question 31

Allosteric modulators

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Binds to a different site on the receptor than the endogenous ligand

Question 32

Allosteric modulators Affects receptor

Answer 32

function through other conformational effects on the protein

Question 33

Partial agonists

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Binds same site as endogenous ligand but elicit a less than maximal response

Question 34

Partial agonists Can

Answer 34

decrease efficacy of the endogenous agonist

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Inverse agonists

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Binds receptor with constitutive activity Has opposite effect to full agonist

Question 36

Tolerance

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Diminished effect of a given dose of drug over time

Question 37

Cross-tolerance

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can cause drug interactions

Question 38

Sensitization

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Enhancement of a particular drug effect on repeated exposure

Question 39

Cross-sensitization

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occurs between drugs acting on the same receptor (e.g. cocaine and amphetamines)

Question 40

Metabolic tolerance

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Increased metabolism through enzyme induction Decreased bioavailability of drug

Question 41

Pharmacodynamic tolerance

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Changes in nerve cell function in response to drug Receptor down-regulation results in saturation and diminished effect

Question 42

Behavioral tolerance

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Context-specific tolerance

Question 43

Habituation

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First administration causes greater alteration of normal behaviour

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Conditioning

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Environment or paraphernalia act as a conditioned stimulus to initiate response

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Persistence of tolerance influenced heavily by

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metabolic and pharmacodynamic mechanisms

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Drug dependence results from

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tolerance mechanisms and is considered a key component contributing to drug addictions

Question 47

Dependence is the

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requirement for drug use in order to maintain ‘normal function’ after the development of drug tolerance

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Tolerance to opiates is proposed to develop as a result of

Answer 48

compensatory mechanisms to restore homeostasis

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Dependence =

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withrawals

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Classifications (DSM, ICD) use

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dependence as the key descriptor of addictions

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Addiction may be better defined as

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compulsive drug-seeking behaviour

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substance/behavioural addictions as

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impulse control disorders

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Intoxication

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Clinically significant problematic behavioural and psychological changes associated with substance intake

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Withdrawal

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Substance-specific problematic behavioural change resulting from discontinuation of use

Question 55

Gateway Hypothesis

Answer 55

he use of a drug of a lower stage is necessary but not sufficient for progression to a higher stage