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PHAR20300 > INTRODUCTION TO PHARMACOLOGY > Flashcards

INTRODUCTION TO PHARMACOLOGY Flashcards

1
Q

Define Pharmacokinetics, Pharmacodynamics and Pharmacotherapeutics and explain how they are related

A
  • Kinetics: How the body metabolises the drug
  • Dynamics: The changes the drug causes in the body
  • Therapeutics: The use of drugs to treat and prevent disease
  • Kinetics+Dynamics=Therapeutics
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2
Q

When a drug produces a response, what is it dependent on?

A
  • The type of target and what the target is linked to:
  • Affinity - degree of attraction
  • Efficacy (intrinsic activity) ability to change target in a way that produces an effect
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3
Q

What is the definition of potency?

A

The quantity of drug required to achieve a desired effect

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4
Q

What are the 3 types of agonist?

A

Full, partial and inverse

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5
Q

What do agonists do?

A

Agonists have affinity and efficacy – they are attracted to a target and produce a response

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6
Q

What do full agonist do?

A

Produce maximal response - they have maximal efficacy and affinity

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7
Q

What do partial agonist do and how do they behave when full agonists are present?

A
  • only PARTIALLY respond, irrespective of drug concentration
  • possesses a lower intrinsic activity than a full agonist
  • a partial agonist acts as an antagonist in the presence of a full agonist (if they compete for the same receptors)
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8
Q

What do inverse agonist do?

A

Binds to the same receptor as an agonist but induces a pharmacological response opposite to that of the agonist
- they only have an effect when the target is continually stimulated by an agonist, this is because inverse agonists suppresses the receptor signalling

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9
Q

Name the 3 types of allosteric modulators

A

Positive - increases affinity, increases efficacy
Negative - decreases affinity, decreases efficacy
Neutral - has no effect on the binding of the agonist

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10
Q

What do allosteric modulators do and how do they do it?

A

Increases (or decreases) the binding of the agonist while having no effect on its own binding (binds to a different site on the receptor - allosteric site)

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11
Q

What do antagonists do?

A

Prevent agonist from binding

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12
Q

Name the different types of antagonist?

A

Competitive - reversible

Non-competitive - binds to allosteric site (irreversible)

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13
Q

What are the four different receptor drug targets?

A

G protein-coupled receptors
Ion channels
Nuclear hormone receptors Protein kinases

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14
Q

Opening of Na+ or Ca2+ ion channel causes…

A

the opening of Na+/Ca2+ channels cause further depolarisation
Ca2+ channels open
Increase in Ca2+
Hence increase in cellular activity

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15
Q

Opening of K+ channels causes…

A

Cause hyperpolarisation (more negative)
Ca2+ channels close
Decrease in Ca2+
Hence decrease in cellular activity

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16
Q

What is an example of a ligand-gated ion channel?

A

Nicotinic acetylcholine receptor

Nicotine is an agonist = causes the Na+ movement (depolarization)

17
Q

What does GTP stand for?

A

Guanosine triphosphate

18
Q

How many lipophilic membrane domains does a GTP receptor have?

A

7 α -helices

19
Q

How many subunits does GTP proteins have?

A

Three subunits (α, β, γ)
G alpha – largest and binds to GTP or GDP
G beta & G gamma which is permanently bond together

20
Q

Describe how GTP coupled receptors work

A
  • Receptor forms complex with alpha-GDP complex
  • GDP exchanged for GTP
  • Alpha-GTP dissociates from G protein and binds to a target protein in the cell (causes changes)
  • GTP is hydrolysed (by GTPase)
  • Alpha subunit rejoins the other subunits of the G protein
21
Q

Describe the activation of adenylyl cyclase by Gs proteins (e.g. b adrenoreceptors)

A
  • The first messengers bind to the receptor, activating Gs protein
  • The G protein releases the alpha subunit, which binds to and activates the adenylyl cyclase
  • Gi-GTP inhibits adenylyl cyclase e.g. opioid receptors
  • this catalyse the conversion of ATP to cAMP
  • cAMP activates protein kinase A
  • protein kinase A catalyses the transfer of a phosphate group from ATP to a protein OR changes the Ca2+ conc
  • The altered protein activity causes a response in the cell
22
Q

Differentiate Gs-GTP and Gi-GTP

A 
Gs-GTP = stimulatory (activates adenylyl cyclase)
Gi-GTP = inhibitory (inhibits adenylyl cyclase)
23
Q

Describe the activation of phospholipase C by Gq proteins

A
  • The messenger binds to the receptor, activating a G protein
  • The G protein releases the alpha subunit, which binds to and activates the phospholipase C
  • Phospholipase C catalyses the conversion of PIP2 to DAG and IP3.
  • DAG remains in the membrane and activates the enzyme protein kinase C.
  • Protein kinase C catalyses the phosphorylation of a protein (leads to a biological response)
  • At the same time:
  • IP3 moves into the cytosol
  • IP3 triggers the release of calcium from the endoplasmic reticulum. (change in Ca2+ conc cause a biological response)
24
Q

Give an example of a Gq-GTP receptors

A

muscarnic receptors and alpha-adrenoceptors

25
Q

What kind of drug is digoxin?

A

cardiotonic

used in heart failure

26
Q

How does digoxin work?

A
  • Digoxin inhibits the Na+/K+-ATPase
  • To reduce the increased Na+, the Na+/Ca2+ exchanger is stimulated,
  • Increase in Ca2+
  • Increase in force of contractions
27
Q

Give an example of a tyrosine kinase receptor

A

Insulin receptor

28
Q

How does a tyrosine kinase receptor work?

A
  • Signal molecule binds
  • Dimerisation of receptor
  • Activate of tyrosine-kinase regions and phosphorylation of the dimer.
  • Dimer goes on to phosphorylate tyrosine molecules and activate inactive relay proteins via this mechanism
  • the phosphorylation of the protein changes its activity, bringing cellular response
29
Q

Give examples of nuclear receptor drugs

A

steroids and thyroid hormones (lipophilic drugs)

30
Q

Name some illnesses associated with malfunctioning nuclear receptors

A

Inflammation, cancer, diabetes, cardiovascular disease, obesity and reproductive disorders

31
Q

How does a nuclear receptor work?

A
  • If a receptor is in the nucleus, the hormone diffuses into the nucleus (through cytoplasm) and binds to it, forming a hormone-receptor complex.
  • Inside the nucleus, the hormone-receptor complex functions as a transcription factor by binding to a region of DNA called the hormone response element (HRE), which is located at the beginning of a specific gene.
  • Binding of the complex to the HRE activates or deactivates the gene, which affects transcription of mRNA and ultimately increases or decreases synthesis of the protein coded by the gene.
  • The mRNA moves into the cytosol
  • The mRNA is translated by ribosomes to yield proteins.
32
Q

Describe speed of:

  • Ligand gated ion channels
  • G protein coupled receptors
  • Kinase-linked receptors
  • Nuclear receptors
A

Milliseconds
seconds
hours
hours-days

PHAR20300 (25 decks)

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