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Principles - Pharmacology > Introduction to Drug Action > Flashcards

Introduction to Drug Action Flashcards

1
Q

What is pharmacodynamics?

A

What a drug does to the body - the biological effects and the mechanism of action

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2
Q

What are pharmacokinetics?

A

What the body does to a drug - absorption, distribution, metabolism and excretion of drugs and their metabolites

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3
Q

What must a drug act with a degree of in order to be useful as a therapeutic agent?

A

Selectivity

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4
Q

What is selectivity?

A

The ability of a drug to distinguish between different molecular targets within the body

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5
Q

What does the acronym ADME stand for and what is it involved in?

A

Absorption
Distribution
Metabolism
Excretion of drugs and their metabolites

Pharmacokinetics

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6
Q

What is the narrow definition of a drug?

A

Any single substance of known structure sed in the treatment, prevention of diagnosis of disease

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7
Q

In what way are penicillins selective?

A

They inhibit an enzyme responsible for cell wall synthesis in bacteria but as animal cells don’t have a cell wall human cells are not affected

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8
Q

What regulatory proteins do many drugs bind to in order to cause an action?

A

Enzymes
Carrier molecules
ion channels
Receptors

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9
Q

What additional targets (aside from proteins) do drugs bind to in order to cause an action?

A

RNA

DNA

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10
Q

What are receptors?

A

Protein macromolecules on or within cells that mediate the biological action of hormones

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11
Q

What are the two types of drugs acting on receptors?

A

Agonists

Antagonists

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12
Q

What his an agonist?

A

A drug that binds to a receptor to produce a cellular response

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13
Q

What is an antagonist?

A

A drug that reduces or blocks the actions of an agonist by binding to the same receptor

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14
Q

What do K+1 and K-1 represent in the agonist equation?

A

K+1 - rate of agonist bindings

K-1 - affinity and efficacy

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15
Q

What is the equation for agonists?

A

A+R (K+1/K-1) AR (beta/alpha) AR*

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16
Q

What is the process of an agonist binding to a receptor?

A

The agonist binds to the receptor, forming an agonist-receptor complex.
This causes a conformational change, leading to a response.
This is reversible

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17
Q

What is the process of going from agonist and receptor to an agonist-receptor complex called?

A

Binding step

affinity

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18
Q

What is the process of the agonist-receptor complex changing confirmation and producing a response called?

A

Activation step

efficacy

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19
Q

What do beta and alpha represent in the agonist equation?

A

Beta - rate of receptor activation

Alpha - rate of receptor deactivation

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20
Q

Do agonists possess affinity or efficacy?

A

Yes, both

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21
Q

What represents affinity?

A

K+1/K-1

22
Q

What represents efficacy?

A

Beta/alpha

23
Q

What is affinity?

A

The strength of association between a ligand and receptor

24
Q

At low affinity, what is the position of equilibrium and the dissociation rate for the binding step?

A

To the left (reactants)

Fast dissociation rate

25
Q

At medium affinity, what is the position of equilibrium and the dissociation rate for the binding step?

A

In the middle

Moderate dissociation rate

26
Q

At high affinity, what is the position of equilibrium and the dissociation rate for the binding step?

A

To the right (products)

Slow dissociation rate

27
Q

What is affinity defined by?

A

Chemical bonds between a ligand and its receptor

28
Q

What is efficacy?

A

The ability of an agonist to evoke a cellular response

29
Q

At low affinity, what is the position of equilibrium for the activation step?

A

To the left - reactants

30
Q

At high affinity, what is the position of equilibrium for the activation step?

A

To the right - products

31
Q

What is an antagonist?

A

A drug that reduces or blacks the actions of an agonist by binding to the same receptor

32
Q

How many steps are involved in agonists?

A

Two

33
Q

How many steps are involved in antagonists?

A

One

34
Q

What is the step for antagonists c called?

A

Binding step

35
Q

Do antagonists possess affinity or efficacy

A

Only affinity

36
Q

What is the action of antagonists?

A

Bind to receptors but do not activate them to block receptor activation by antagonists

37
Q

How is the relationship between concentration (or dose) and effect described?

A

Hyperbolic

steep gradient then decreasing until tapers off

38
Q

What is EC50(/ED50)?

A

The concentration of agonist that elects a half maximal effect

39
Q

What is AR*?

A

The activated agonist-receptor complex

40
Q

What does EC50/ED50 stand for?

A

EC - effected concentration

ED - effected dose

41
Q

Why are linear graphs of concentration against effect converted into logarithmic graphs?

A

EC50 is easier to tell on a logarithmic lot

42
Q

On a semi-logarithmic plot, how is the relationship between concentration and effect described?

A

Sigmoidal - s shaped

43
Q

What is potency?

A

A measure of drug activity expressed in terms of the amount required to produce an effect of given intensity.

44
Q

What is used when comparing drugs on a semi-logarithmic graph?

A

EC50

45
Q

How can reversible competitive antagonism be overcome?

A

Increasing the concentration of agonist

46
Q

What is reversible competitive antagonism?

A

The binding of agonist and antagonist, both of which are reversible, occur at the same (orthosteric) site

47
Q

What is non-competitive antagonism?

A

An agonist binds to the orthosteric site and antagonist binds to a separate allosteric site and thus this is not competitive
Both may occupy receptor at same time but activation cannot occur when antagonist is bound

48
Q

What do competitive antagonists cause to happen to a semi-logarithmic graph?

A

Parallel rightward shift of agonist response curve but maximum response is unchanged

49
Q

What do non-competitive antagonists cause to happen to a semi-logarithmic graph?

A

Depress the slope and the maximum of the concentration response curve but no rightwards shift

50
Q

What is the effect of increasing the concentration of a competitive antagonist on a semi-logarithmic graph?

A

Progressive rightward shift, no depression of slope or maximum response

51
Q

What is the effect of increasing the concentration of a non-competitive antagonist on a semi-logarithmic curve?

A

Progressive depression of maximum response and slope, but no rightward shift

52
Q

What are partial agonists?

A

Ones with lower efficacy than full agonists

Principles - Pharmacology (3 decks)

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