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Pharmacology > Drug Targets > Flashcards

Drug Targets Flashcards

1
Q

TIER

4 methods by which drugs function

A
  1. Receptors
  2. Ion channels
  3. Enzymes
  4. Transporters (protein in nature)
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2
Q

With drugs, they apply to mostly protein targets with the exception of…

A

Targets of chemotherapy - often bind to DNA

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3
Q

Name the top 5 MOAs of drugs

A
  1. Enzyme inhibitor
  2. Receptor agonist
  3. Receptor antagonist
  4. Transporter blocker
  5. Ion channel blocker
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4
Q

What are receptive substances

A

There is a substance or substances in the nerve endings or gland cells with which both atropine and pilocarpine are capable of forming compounds

Receptive side chains to which chemical substances bind to produce effects - such binding involves weak bonds

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5
Q

What is propranolol

A

A beta receptor antagonist

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6
Q

What are H2 receptor antagonists

A

Anti-ulcer compounds

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7
Q

What is the MOA of aspirin

A

Inhibits the action of prostaglandins - substances that are liberated when tissues are perturbed producing inflammation, pain and fever in the body

(specifically inhibits the enyme cyclooxygenase that is responsible for production of prostaglandins)

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8
Q

What is a side effect of low dose aspirin

A

Stops the production in platelets of thromboxane, which causes platelets to stick together to plug any ruptures in BVs

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9
Q

What are receptors

What are they in nature

What do they do

Where are they found

A
  • Recognition molecules for chemical mediators
  • Large proteins (specialised structure)
  • Linked to other molecules within the cell & trigger a response in that cell
  • Found on cell membrane surface, cytosol, nucleus
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10
Q

What are endogenous ligands

What are they similar to

Give an example

A
  • The body’s own ‘drugs’
  • Drugs bind to receptors in the same way that endogenous ligands bind to receptors
  • e.g. adrenaline is the endogenous ligand for beta receptors - isoprenaline (isoproterenol) is a synthetic drug that binds to the same receptor
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11
Q

What is adrenaline the endogenous ligand for

A

Beta receptors

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12
Q

Name the synthetic drug that binds to beta receptors

A

Isoprenaline (isoproterenol) is a synthetic drug that binds to the same receptor

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13
Q

Explain ligand specificity

How many receptors can a drug bind to

A
  • Lock and key
  • Receptors are specific for a particular ligand or drugs
  • A drug may bind to more than 1 receptor
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14
Q

What is amitriptyline

What is its MOA

What does it bind to

A
  • Amitriptyline is a tricyclic antidepressant
  • MOA is inhibition of the neuronal reuptake of noradrenaline and serotonin
  • Also binds to other targets such as the muscarinic and histamine H1 receptor
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15
Q

What does specificity depend on

A

Shape, which depends on folding in response to pH, water, lipid etc

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16
Q

How does drug-receptor binding occur

A

Multiple chemical interactions, the sum of which provides specificity

17
Q

Specificity of drugs

A

No drug is completely specific

18
Q

What is affinity

A

Favourability of the interactions i.e. amitriptyline has a high affinity for a number of drug targets

19
Q

What is adrenaline’s receptor

A

B2 receptor

20
Q

What are the 2 main drug-receptor bonds

A
  • Van der Waals
  • Hydrogen bonds
21
Q

What are the 4 characteristics that affect binding

A
  1. PHYSICAL NATURE: solid, liquid, gaseous, organic, inorganic
  2. DRUG SIZE: range from very small to very large (most MWs lie between 100-1000)
  3. DRUG REACTIVITY: electrostatic bonds with target
  4. DRUG SHAPE: chirality (stereoisomerism), more than half of drugs are chiral molecules (exist as enantiomeric pairs)
22
Q

What is Imatinib

What does it interact with & how

What does its binding with its receptor cause

A
  • Imatinib is a highly selective inhibitor of the BCR-Ab1 tyrosine kinase fusion protein
  • Imatinib interacts with specific AA residues that possess hydrophobic side chains via van der Waals forces and hydrogen bonding
  • The binding causes a conformational change in the active site of the enzyme, inhibiting its catalytic activity
23
Q

Define affinity

What is it measured by

What does it enable us to do

A
  • The strength of the reversible interaction between a drug and its receptor
  • Tendency of a drug to bind to a receptor
  • Measured by Kd
  • This measurement enables us to compare the affinities of drugs i.e. how avidly they bind to their target receptors
24
Q

What is occupancy

A

The rate at which drugs (D) combine with their receptors (R) depends on the combination of drug and receptor

The rate of dissociation depends on the number of complexes (DR) formed

25
Q

What is the Law of Mass Action

A
26
Q

Explain drug-receptor occupancy curves

A

As the conc of drug in the vicinity of its receptor is increased, then the proportion of receptors occupied increases

As there are a finite number of receptors, a conc point will be reached when all of these receptors are occupied

* a sigmoid curve is created

27
Q

What is Bmax

What is Kd

A
  • Bmax = density of receptors at maximum binding
  • Kd (equilibrium constant) = conc of drug required to occupy 50% of receptors

Pharmacology (23 decks)

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