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OP2205 > 4. Principles of drug action > Flashcards

4. Principles of drug action Flashcards

1
Q

What is pharmacology?

A

It is the study of interacts between chemicals and living systems.

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2
Q

What are drugs?

A

Drugs are chemical substances which, by interacting with biological systems, are able to change them in some way. Drugs have effects example: contraction of muscles, secretion by glands, release of hormones.

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3
Q

What are the properties of an ideal drug? (EECSSRPFL)

A
  1. Effective
  2. Ease of administrations
  3. Chemical stability
  4. Safety
  5. Selectivity
  6. Reversible action
  7. Predictability
  8. Freedom from drug interaction
  9. Low cost
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4
Q

What is a receptor?

A

A target molecule through which physiological mediators (neurotransmitters, hormones) produce their effect.

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5
Q

Site of action for drugs?

A

Receptors

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6
Q

Class of receptor?

A

Protein

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7
Q

Location of receptors?

A

Plasma membrane- on cell membrane surface.

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8
Q

What is a signaling molecule and what does it bind to?

A

Ligand is a signaling molecule
It binds to specific receptors

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9
Q

Role of receptors

A

Used by cells to send signals either intracellularly or extracellularly.

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10
Q

True or false: Ligand has more than 1 receptor?

A

True- ligand has a choice of which receptor to bind to

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11
Q

What is the macroscopic effects?

A

When there is a large population of receptors (e.g., within the membrane of a cell), any given ligand molecule has a choice of receptors with which to bind. In this case, the interaction follows a set pattern called the dose-response curve.

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12
Q

What is a dose- response curve?

A

Represents the relationship between drug concentration and drug effect. Y-axis shows the response/effect. X axis shoes the dose.

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13
Q

On the dose- response curve, what does the following mean: E and Emax?

A

E: Effect
Emax: Maximal effect

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14
Q

What is seen when a dose-response curve is plotted on a log scale?

A

The curve has a sigmoidal curve shape

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15
Q

What is E50% on the log dose-response curve?

A

This is the summary value that gives half-maximal effect

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16
Q

What does it mean that a drug has specificity?

A

Receptor and ligand fit like a lock and key: specificity is a function of the ligand’s shape and the receptor’s binding site.

17
Q

Receptors show high level of ligand specificity, explain

A

2 different ligands may be able to bind to the same receptor but how tightly they bind and how long they remain bound may be different.

18
Q

What is meant by affinity?

A

How well a drug binds to a receptor

19
Q

What is Kr and Kf in the rate constant equation?

A

Kr- forward rate constant
Kf- backward rate constant
This 2 rate constants are used to calculate the equilibrium constant.

20
Q

What is Kd?

A

Equilibrium constant
This is the concentration of drug required to occupy 50% of sites at equilibrium.
Kd also relates to the concept of affinity

21
Q

How is affinity calculated?
Relationship between affinity and Kd?

A

AFFINITY= 1/Kd
Affinity is how well a drug can bind to a receptor.
Drugs that bind tightly how a low equilibrium constant

22
Q

Agonist meaning

A

Drugs that bind to receptors and do initiate a response. Activate receptors and produce subsequent responses.

23
Q

Antagonist meaning

A

Drugs that bind to receptors and do not initiate a response. No activation, occupy the receptor and blocking.

24
Q

Potency meaning

A

Refers to the quantity of drug that must be administered to produce a specific effect.

25
Q

Agonist potency depends on what 2 parameters?

A

Affinity and Efficacy

26
Q

What is the efficacy for antagonists and agonists?

A

Antagonists: Efficacy is 0
Agonists: Efficacy is significant

27
Q

Synonym of efficacy?

A

Intrinsic activity

28
Q

Meaning of affinity and efficacy?

A

Affinity: tendency to bind to receptors.
Efficacy: ability, once bound, to initiate changes that lead to effects.

29
Q

Affinity describes?

A

How well a ligand will bind to its receptors

30
Q

Efficacy describes?

A

How well a ligand will stimulates a receptor

31
Q

True of false; affinity and efficacy are largely independent of each other?

A

True

32
Q

Dose- response curve provides information about?

A

Efficacy and potency

33
Q

Characteristics of a good potent drug?

A

Most potent drug: lower dose required to produce a big response

34
Q

What is meant when a drug is selective??

A

Means drugs ability to preferential produce a particular effect

35
Q

True of false: drugs can be selective or non-selective?

A

True

36
Q

Which neurotransmitter is released by cholinergic fibres vs adrenergic fibres?

A

Cholinergic fibres: Ach
Adrenergic fibres: NE

37
Q

On the dose- response curve, what is measured along the horizontal axis vs the vertical axis?

A

Horizontal axis: Potency
Vertical axis: Efficacy

OP2205 (8 decks)

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