PHARMACOLOGY 3 Flashcards Preview

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Flashcards in PHARMACOLOGY 3 Deck (56)
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1
Q

what is Pharmacodynamics?

A

Study of how drugs affect the body

2
Q

what does Pharmacodynamics involve?

A

qualitative (descriptive) and quantitative (numbers) research to identify potential drug targets

3
Q

what does Qualitative research do?

A

determines the mechanisms of action drugs

4
Q

what does Quantitative research do?

A

to determine dosage, safety, contraindications, side effects and drug interactions

5
Q

what are the 4 major drug targets?

A

ion channels
receptors
transporter proteins
enzymes

6
Q

what do ion channels target?

A

can target Na+, K+, Ca2+, and Cl-

7
Q

what do receptors target?

A

can target Type 1 (ionotropic), Type 2 (G-coupled receptors), Type 3 (receptor tyrosine kinase) and Type 4 (nuclear receptors) receptors

8
Q

what do transporter proteins target?

A

Can target release of neurotransmitters

9
Q

what do enzymes target?

A

can target re-uptake of neurotransmitters , ie acetylcholinesterase

10
Q

what are the 4 major drug properties?

A

Selectivity
Specificity
Potency
Efficacy

11
Q

what is Drug Selectivity?

A

describes the ability of a drug to bind to a particular receptor. However some drugs bind to more than 1 receptor - thus have low selectivity.

12
Q

give an example of Drug Selectivity

A

propranolol – a β-blocker

Binds to β1 and β2 adrenergic receptors

13
Q

what does blockage of β1 receptor do?

A

decreases heart rate and the force of contraction of the heart

14
Q

what does blockage of β2 receptor do?

A

inhibits bronchial smooth muscle relaxation – thus can cause a bronchospasm in asthmatics and sufferers of COPD

15
Q

what is Drug Specificity?

A

refers to how drugs interact with a receptor when bound

16
Q

what is ligand specificity?

A

Drug targets such as receptors have a configuration giving them a specificity for specific signaling molecules (ligands)

17
Q

can receptors bind with ligands that have slightly different configurations?

A

yes

18
Q

what happens when ligands with high specificity bind to a receptor?

A

give rise to a specific effect

19
Q

what effect so low specificity ligands have?

A

have different effects on that receptor. If combined with low selectivity may have different effects on other receptors.

20
Q

what is Drug Potency?

A

Refers to dosage of drug needed to induce an effect.

21
Q

what is Drug Potency dependent on?

A

receptor affinity

22
Q

how will a drug with low affinity bind?

A

weakly bind to a receptor and will readily dissociate from that receptor

23
Q

how so low affinity drugs have an effect?

A

need large doses

24
Q

how will a drug with high affinity bind?

A

will bind strongly to a receptor and stay bound to that receptor giving rise to a large physiological response at low conc

25
Q

what is Drug Efficacy?

A

describes the ability of a drug to induce an effect

26
Q

what effect does Drug Efficacy have?

A

Can have full agonists and partial agonists effect

27
Q

what is full agonist?

A

at specific doses can induce a full physiological response, i.e. a full and maximal muscle contraction

28
Q

what is partial agonist?

A

describes a drug that cannot induce a full physiological response regardless of the dose

29
Q

how are partial agonist useful?

A

useful in healthcare because they can have a therapeutic effect without a risk of overdose

30
Q

what is studied by Dose Response Curves?

A

Potency and efficacy

31
Q

what does creating a Dose Response Curves involve?

A

Involves measuring tissue response (force of contractions) to treatment with increasing drug conc until a maximum response is reached (Emax)

32
Q

what is the quantal response?

A

all or nothing response i.e. a patient responding or not responding to a drug.

33
Q

how can you examine a quantal response to a drug?

A

by taking a sample of the population and determining the dose at which a drug has an effect

34
Q

what is Median lethal dose (LD50)?

A

Lethal dose for 50% of users

35
Q

what is Medial toxic dose (TD50)?

A

Toxic dose for 50% of users

36
Q

what is Therapeutic Ratio?

A

Therapeutic dose that produces a therapeutic effect in half of treated – Median effective dose (ED50)

37
Q

what are the 5 main mechanisms of drug antagonism?

A
Chemical antagonism 
Receptor antagonism 
Non- competitive antagonism
Pharmacokinetic antagonism
Physiological antagonism
38
Q

what is Chemical antagonism?

A

when drugs reduce the concentration of an agonist

39
Q

what is Receptor antagonism also known as?

A

Competitive antagonism

40
Q

what is Receptor antagonism?

A

Describes the blockade of a receptor by a drug molecule.

41
Q

what are antagonists?

A

compete with the agonist for receptor site (competitive antagonism)
have no efficacy, but have an affinity

42
Q

what is low affinity?

A

Reversible competitive antagonism

43
Q

what is high affinity?

A

Irreversible competitive antagonism

44
Q

what is non-competitive antagonist?

A

Drug binds to an allosteric site (non-agonist) site on the receptor and prevent activation
may activate singling pathways
Converts a full agonist into a partial agonist.

45
Q

what is Pharmacokinetic Antagonism?

A

Antagonist drug that acts to increase clearance, reduce plasma concentrations and effect half life of active drug in the body

46
Q

what is Physiological Antagonism?

A

Interaction between 2 drugs that initiate opposing effects via different receptors in the same target tissue

47
Q

what is tolerance?

A

associated with maintenance of drug response requiring increasing doses

48
Q

what is tolerance caused by?

A

Pharmacokinetic mechanisms

Pharmacodynamic mechanisms

49
Q

how does Pharmacokinetic mechanisms cause tolerance?

A

Metabolism of drug increasing because of up regulation of enzymes that breakdown the drug and it is rapid eliminated from the body.

50
Q

how does Pharmacodynamic mechanisms cause tolerance?

A

down regulation of receptors

51
Q

what is cross tolerance?

A

repeated use of a drug effects the therapeutic function of another drug

52
Q

what is cross tolerance caused by?

A

caused by shared signaling pathways or metabolic pathways

53
Q

what is Desensitisation?

A

Lack of receptor response after prolonged stimulation. Can be short term or long term.

54
Q

what is Short term Desensitisation?

A

due to post-translation modification of the receptor – deactivation

55
Q

what is Long term Desensitisation?

A

Associated with changes in gene regulation

56
Q

what is Tachyphylaxis?

A

Describes desensitisation associated with the depletion an intermediate signaling molecule or depletion of the pool of neurotransmitter in the synaptic vesicles arising from over stimulation