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MBChB Year 1 Principles Pharmacology > General Principles of Drug Action > Flashcards

General Principles of Drug Action Flashcards

Intro to Pharmacology

1
Q

What is pharmacodynamics?

A

What a drug does to the body

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2
Q

What is pharmacokinetics?

A

What the body does to a drug (ADME)

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3
Q

What is a drug?

A

Any single synthetic (or natural) substance of known structure used in the treatment, prevention or diagnosis of disease - can be everyday substances or illicit

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4
Q

What is a medicine?

A

A chemical preparation containing one, or more, drugs used with the intention of causing a therapeutic effect (usually include additional agents to the active drug)

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5
Q

How can a drug be a useful therapeutic agent?

A

Must act with a degree of selectivity

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6
Q

What is selectivity?

A

The ability of a drug to distinguish between different molecular targets in the body

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7
Q

What does selectivity allow drugs to do?

A

To interact with select cells and tissues to produce their desired effect by binding to particular molecular targets expressed on these cells

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8
Q

How does penicillin work?

A

Inhibit the enzyme responsible for cell wall synthesis in bacteria (essential for survival) but doesn’t affect the mammalian cell as it doesn’t have the cell wall or enzyme

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9
Q

What types of regulatory proteins do drugs bind to?

A

Enzymes, carrier proteins (transporters and pumps), ion channels and receptors

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10
Q

Other than proteins what else can a drug’s target be?

A

RNA and DNA

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11
Q

What are drug receptors?

A

Protein macromolecules on, or in, cells that mediate the biological actions of hormones, neurotransmitters and other endogenous substances

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12
Q

What is an agonist?

A

A drug that binds to a receptor to produce a cellular response

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13
Q

What is an antagonist?

A

A drug that reduces, or blocks, the actions of an agonist by binding to the same receptor

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14
Q

How do agonists activate receptors?

A

By binding to them temporarily and inducing a reversible conformational change

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15
Q

What is drug affinity?

A

The magnitude of agonist binding and unbinding (ratio of rate constants) - K+1/K-1

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16
Q

What is drug efficacy?

A

The ability of a bound agonist to promote a conformational change/activate receptor (alpha/beta)

17
Q

What changes in affinity?

A

K-1 (not K+1!!!)

18
Q

What is drug selectivity dependent on?

A

The dose (and often the way it is administered)

19
Q

What side of equilibrium does a high affinity favour?

A

The product(s)

20
Q

What side of equilibrium does low efficacy favour?

A

The reactants

21
Q

What type of bonds determine affinity?

A

Chemical - ionic, hydrogen and aromatic (pi-pi)

22
Q

Why can drug selectivity not be described as specific?

A

As there is an ‘on target’ (ideal) but there’s also an ‘off target’ (not good news if the drug binds here)

23
Q

Do antagonists have affinity or efficacy? Why?

A

Affinity as they DON’T activate anything so can’t have efficacy

24
Q

When concentration-effect relationship is plotted linearly, what is the effect on the curve?

A

Hyperbolic

25
Q

When concentration-effect relationship is plotted semi-logarithmically, what is the shape of the curve?

A

Sigmoidal

26
Q

What is EC50?

A

The concentration of agonist that causes a half maximal effect - if dose related ED50 (think Km from Michaelis-Menten)

27
Q

What is a full agonist?

A

An agonist not capable of producing the maximal response

28
Q

What is a partial agonist?

A

An agonist not capable of producing the maximal response (has a lower efficacy)

29
Q

If an agonist AND an antagonist are bound to the same receptor is it active?

A

No

30
Q

What is reversible competitive antagonism?

A

When the agonist and antagonist (both reversible) bind at the same (orthosteric) site = mutually exclusive

31
Q

How do you overcome reversible competitive antagonism?

A

Increase the concentration of agonist

32
Q

What is non-competitive antagonism?

A

When the agonist binds to the orthosteric site and the antagonist binds to the allosteric site = no competition. Can be reversible and simultaneous

33
Q

How do competitive antagonists affect the sigmoidal curve?

A

Rightward shift of agonist concentration (for the same effect) but maximal response stays the same - need higher concentration to overcome

34
Q

How do non-competitive antagonists affect the sigmoidal curve?

A

Depress the slope and maximum concentration (for same response) but no rightward shift

MBChB Year 1 Principles Pharmacology (3 decks)

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