Pharmacodynamics - Main Principles

Question 1

What is pharmacology and what are its two branches?

Answer 1

The study of drugs - what they are, how they work, and what they do

Pharmacodynamics = what a drug does to the body (mechanism of action and biological effect)

Pharamcokinetics = what the body does to a drug (absorption, distribution, metabolism, and excretion and the rate of each of these processes)

Question 2

What is the difference between generic and brand names?

Answer 2

Generic = unique and nonproprietary name used to identify a unique pharmacologically active ingredient, pharmacologist (nearly) always use the generic name

Brand = Proprietary name given by the pharmaceutical company, several names may exist for the same generic drug name, pharmacists will typically use this name

Question 3

How do drugs act and how are they specific / selective?

Answer 3

Drugs act by binding to target molecules
Specificity / selectivity comes from both the drug’s chemical structure and the receptors recognsing only a precise ligand

Question 4

What are the regulatory proteins that drugs bind to in order to act?

Answer 4

1. Receptors (there are 4 types)
2. Enzymes (separate from kinase/enzyme linked receptors)
3. Ion channels - voltage gated (separate from ligand-gaated ion channels)
4. Carrier molecules (transporters and pumps)

Question 5

What is an agonist?

Answer 5

A drug or substance that binds to a receptor inside a cell or on its surface and causes the same action as the substance that normally binds to the receptor

Question 6

What is the relationship between agonist concentration and receptor occupancy?

Answer 6

Agonist at low concentration = lower receptor occupancy
Agonist at high concentration = high receptor occupancy

Relationship between concentration (dose) and response is sigmoidal
If you take more than maximum, you don’t actually increase response, just introduce unwanted effects. Therefore, minimum concentration (dose) is required.

Question 7

What is competitive and non-competitive antagonism?

Answer 7

Competitive antagonism = Binding of agonist and antagonist occur at the same site and is thus competitive and mutually exclusive. If there are more antagonists it is unlikely for agonists to reach the receptor, therefore that receptor should be considered blocked

Non-competitive antagonism = Agonist binds to orthosteric site and antagonist binds to a seperate allosteric site and thus is not competitive. Both may occupy the receptor simultaneously, but activation cannot occur when antagonist is bound

Question 8

What are the causes of unwanted side effects (adverse drug reactions) from both a pharmacodynamic and pharmacokinetic perspective?

Answer 8

Phamacodynamics = idiosyncratic unpredictable, non-specific off target effects and also predicable known effects

Pharmacokinetics = drug-drug ineractions and often due to altered drug metabolism