Pharmacodynamics Flashcards

1
Q

Pharmacodynamics

A

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

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2
Q

Ligand

A

any molecule that binds to a receptor

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3
Q

Drug

A

exogenous ligand

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4
Q

Neurotransmitters, hormones, peptides

A

endogenous ligands

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5
Q

Receptor

A

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

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6
Q

receptor examples

A

neurotransmitters, hormones, peptides, drugs

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7
Q

Extracellular receptors

A

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

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8
Q

intracellular receptors

A

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

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9
Q

extracellular receptor types are common targets for

A

psychoactive drugs

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10
Q

Ligand-gated ion channels

A

Postsynaptic neurotransmitter receptors

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11
Q

G-protein coupled receptors (GPCR)

A

Metabotropic receptors
Intracellular second messenger

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12
Q

Receptor kinases

A

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

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13
Q

intracellular receptor types are common targets for

A

steroid hormones and lipophilic compounds (and some drugs)

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14
Q

intracellular chemicals

A

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

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15
Q

Intracellular receptors are located

A

in cytoplasm

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16
Q

Hormone receptors

A

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

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17
Q

Agonist

A

interactions are those that elicit a biological effect on the receptor

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18
Q

Antagonist

A

interactions are those preventing or blocking a biological effect

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19
Q

dose-response

A

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

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20
Q

Potency

A

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

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21
Q

TD50

A

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

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22
Q

LD50

A

measures the potency at eliciting a lethal effect.

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23
Q

Therapeutic index

A

reflects the margin of safety between drug efficacy and adverse effects

24
Q

therapeutic index calculation

A

TI = TD50 / ED50

25
Q

In contrast to agonists, antagonists can be

A

be reversible or irreversible

26
Q

Reversible antagonists can be displaced by the

A

endogenous agonist

27
Q

Competitive antagonism

A

Reduces agonist potency but not efficacy

28
Q

Non-competitive antagonists cannot be

A

displaced by agonists

29
Q

Irreversible antagonists

A

Binds irreversibly to the same binding site as an endogenous ligand

30
Q

Non-competitive antagonists Reduce drug

A

efficacy and sometimes potency

31
Q

Allosteric modulators

A

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

32
Q

Allosteric modulators Affects receptor

A

function through other conformational effects on the protein

33
Q

Partial agonists

A

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

34
Q

Partial agonists Can

A

decrease efficacy of the endogenous agonist

35
Q

Inverse agonists

A

Binds receptor with constitutive activity
Has opposite effect to full agonist

36
Q

Tolerance

A

Diminished effect of a given dose of drug over time

37
Q

Cross-tolerance

A

can cause drug interactions

38
Q

Sensitization

A

Enhancement of a particular drug effect on repeated exposure

39
Q

Cross-sensitization

A

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

40
Q

Metabolic tolerance

A

Increased metabolism through enzyme induction
Decreased bioavailability of drug

41
Q

Pharmacodynamic tolerance

A

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

42
Q

Behavioral tolerance

A

Context-specific tolerance

43
Q

Habituation

A

First administration causes greater alteration of normal behaviour

44
Q

Conditioning

A

Environment or paraphernalia act as a conditioned stimulus to initiate response

45
Q

Persistence of tolerance influenced heavily by

A

metabolic and pharmacodynamic mechanisms

46
Q

Drug dependence results from

A

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

47
Q

Dependence is the

A

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

48
Q

Tolerance to opiates is proposed to develop as a result of

A

compensatory mechanisms to restore homeostasis

49
Q

Dependence =

A

withrawals

50
Q

Classifications (DSM, ICD) use

A

dependence as the key descriptor of addictions

51
Q

Addiction may be better defined as

A

compulsive drug-seeking behaviour

52
Q

substance/behavioural addictions as

A

impulse control disorders

53
Q

Intoxication

A

Clinically significant problematic behavioural and psychological changes associated with substance intake

54
Q

Withdrawal

A

Substance-specific problematic behavioural change resulting from discontinuation of use

55
Q

Gateway Hypothesis

A

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