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Flashcards in Basic Principles of Pharmacology Deck (40)
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1
Q

How does a drug work

A

By binding to something (e.g. receptors, enzymes, ion channels or transporters)

2
Q

Define pharmacodynamics

A

The study of how drugs act on the living body

3
Q

Define agonist

A

A ligand that binds and induces a response

4
Q

Define full agonist

A

An agonist that produces a maximal effect. It has high efficacy

5
Q

Define partial agonist

A

An agonist that produces a submaximal effect. It has an intermediate efficacy

6
Q

What is the difference between a full and partial agonist

A

A full agonist produces a maximal effect, whilst a partial agonist produces a submaximal effect

7
Q

What shaped dose-response curve does a full agonist give

A

Sigmoidal (S shaped)

8
Q

What shaped dose-response curve does a partial agonist give

A

Sigmoidal (S shaped), but more shallow than a full agonist

9
Q

Define a competitive antagonist

A

A ligand that competes with the agonist to bind to the receptor

10
Q

Define a non-competitive antagonist

A

A ligand that binds to a site that is not the active site and alters the receptor such that the agonist cannot bind

11
Q

Define a reversible antagonist

A

An antagonist that can be washed out. Binding is not permanent

12
Q

Define an irreversible antagonist

A

An antagonist that cannot be washed out. Binding is permanent.

13
Q

What is the dose-response curve for a reversible competitive antagonist

A

Parallel shift to the right. No change in maximal response

14
Q

What is the dose-response curve for an irreversible competitive antagonist

A

No shift. Maximal response reduced

15
Q

What is the dose-response curve for a reversible non-competitive antagonist

A

No shift. Maximal response reduced. No change in EC50 value

16
Q

What is the dose-response curve for an irreversible non-competitive antagonist

A

No shift. Maximal response reduced. No change in EC50 value. Maintains sigmoidal shape.

17
Q

Define physiological antagonism

A

A ligand that acts in a different place. Causes a different bodily function to counteract the undesirable one

18
Q

Define chemical antagonism

A

An antagonist that reduces the concentration of an agonist by forming a chemical complex with it

19
Q

Define pharmacokinetic antagonism

A

An antagonist that affects absorption, distribution, metabolism or elimination

20
Q

Define affinity

A

The ability of the drug to bind to the target

21
Q

Define efficacy

A

The ability of the drug to induce a conformational change (activation)

22
Q

What is the affinity and efficacy of an agonist

A

Full agonists have high efficacy. Partial agonists have intermediate efficacy

23
Q

What is the affinity and efficacy of an antagonist

A

They have no efficacy because no response is induced.

24
Q

How does a ligand gated ion channel initiate a biological response

A

Agonist binding causes a conformational change which causes the ion channel to open

25
Q

Give an example of a ligand gated ion channel

A

Nicotinic acetylcholine receptor

26
Q

How does a GPCR initiate a biological response

A

Agonist binding causes stimulation of a secondary messenger signalling cascade

27
Q

How does a receptor tyrosine kinase initiate a biological response

A

Similar to a GPCR. Except the intracellular domain contains tyrosine kinase

28
Q

How does an intracellular hormone receptor initiate a biological response

A

Ligand activates transcription factors. Factors regulate gene expression by interacting with specific DNA sequences

29
Q

What are the four key stages of pharmacokinetics

A

Absorption, Distribution, Metabolism, Excretion

30
Q

Define drug absorption

A

How a drug enters the blood stream

31
Q

What does drug distribution depend on

A

Physical and chemical properties of the drug. The drugs ability to penetrate cell membranes

32
Q

Define the first pass effect and its importance

A

When drugs pass through the liver they tend to be converted to less active alternatives. Most drugs need to be able to be active after the first pass

33
Q

Define EC50 value

A

The concentration of agonist needed to produce 50% of the maximal response

34
Q

Define IC50 value

A

The concentration of antagonist needed to inhibit 50% of maximal response

35
Q

Define ED50 value

A

Minimum dose required to show desired activity in half of the tested population after a specific duration of time

36
Q

Define LD50 value

A

The dose required to kill half of the members of the tested population (LD = lethal dose)

37
Q

Define therapeutic index

A

The ratio of ED and LC.

38
Q

What is the importance of the therapeutic index

A

Defines a useable drug dose which will show activity, but not kill.

39
Q

What are the four stages of a clinical trial

A

1 - check for safety
2 - check for efficacy
3 - confirm findings in a larger population group
4 - test long-term safety in diverse patient population

40
Q

Define ‘drug’

A

A substance of known chemical structure, which when administered to a living organism produces a biological effect