Pharmacology - Pharmacodynamics I

Question 1

Define pharmacology

What does it divide into?

Answer 1

Study of drugs interacting with living systems

Pharmacodynamics and Pharmacokinetics

Question 2

Define pharmacodynamics

Answer 2

Effect of drugs on biological system

Question 3

Define pharmacokinetics

Answer 3

Effect of biological system on drugs

Question 4

What is a drug?

Answer 4

Any substance that brings about a change in biological function through its chemical actions

Question 5

What are the biological systems involved in pharmacodynamics?

Answer 5

Molecular, Cellular, Organ, Organism

Question 6

Describe pharmacodynamics in terms of measurement

Answer 6

Measurement of magnitude of response to drugs (relates to dose/conc of drug)

Question 7

What are the different types of mechanisms?

Answer 7

Non-receptor and receptor based

Question 8

Describe non-receptor mechanisms

Answer 8

Change physical chemical property eg antacids

Question 9

Name examples of receptor based mechanisms

Answer 9

Receptors, Enzymes, Carrier, Ion channels

Question 10

What are receptors?

Answer 10

Part of cell which the drug recognises and binds to

Question 11

Describe receptor mediated mechanisms

Answer 11

Usually proteins receptors (lock and key), Not all same receptor so drug binds to right cell for right effect

Question 12

Describe receptor classification

Answer 12

Histamine - Effects H1 receptor but more effective on H2 for gastric secretion

Question 13

What is classification based on?

Answer 13

Drug binding, Ligand binding to receptors, Molecular cloning of AA sequences

Question 14

What is a bioassay?

Answer 14

Process which the activity of a substance is measured on living material

Question 15

Describe the major difference between agonist and antagonist?

Answer 15

Agonist binds/activates receptor, Antagonist (inhibits agonist) binds to receptor but no activation

Question 16

What is a dose-response relationship?

Answer 16

RS btw conc of drug at receptor site and magnitude of response

Question 17

What is pharmacokinetics?

What does it measure and predict?

Answer 17

Fate of drugs
Rates of absorption, Distribution, Metabolism, Excretion
Predicts plasma levels in relation to dose given

Question 18

Things to consider with PK medication

Answer 18

Right medication, patient, dosage, form/route, time

Question 19

What is the therapeutic window?

What is the best way to administer?

Answer 19

Increasing drug conc increases response but also increases adverse effects
Infusion via IV

Question 20

Define the law of mass action

Answer 20

RoR dependent on conc of reagents

Question 21

What are the 3 major factors that determine magnitude of response to drugs?

Answer 21

1. Number of drug molecules present
2. Proportion of available receptors occupied by drug
3. Rate at which drug-receptor complexes form/break

Question 22

Describe the 2 steps when an agonist binds/activates a receptor

Answer 22

Occupation - Drug binds to receptor

Activation - Receptor affected by bound drug and changes shape

Question 23

Using the 2 steps, how can you quantify pharmacological measures?

Answer 23

Radioligand binding - Radiolabel attached to drug ligand/receptor (RECEPTOR OCCUPATION)
Functional living in vitro system eg organ bath/bioassay (RECEPTOR ACTIVATION)

Question 24

Describe an example of occupation in terms of KD (dissociation constant)

Answer 24

Drug conc needed to saturate 50% of receptors at equi (lower KD, greater drug’s affinity for receptor - Needs less drug to have an effect)

Question 25

What is KD?

Answer 25

A constant, the same for receptors and drug combos in any tissue/species if its the same receptor

Question 26

What is KD used for?

Answer 26

Identify unknown receptor or compare affinity of diff drugs on same receptor

Question 27

What is KA in terms of radioligand binding?

Answer 27

Measure of agonist affinity - Tendency of drug to bind to receptor
HIGHER AFFINITY, HIGHER POTENCY

Question 28

Describe measuring the effects of receptor activation

Answer 28

Agonist binds to receptor, elicits response that activates ion channel opening, G-protein activation or enzyme activation depending on receptor type

Question 29

Define affinity

Answer 29

Tendency of drug to bind a receptor

Question 30

Define efficacy (Emax)

Answer 30

When bound, ability of drug to activate a receptor

Maximal measured effect of drug

Question 31

Define potency (EC50)

Answer 31

Amount of substance needed for it to be efficacious

This is the dose/conc where substance reaches 50% of its maximal efficacy

Question 32

Describe a lower potency (EC50)

Answer 32

Less amount of drug needed to produce 50% of max effect so higher potency

Question 33

What are the in vitro measures?

Answer 33

Emax, EC50, ED50

Question 34

Describe the difference between EC50/ED50

Answer 34

EC50 - Conc that produces 50% of max effect

ED50 - Dose that produces 50% max effect

Question 35

Describe partial agonists

Answer 35

Have an affinity for receptor but lower efficacy - Less activation caused by binding

Question 36

Describe muscle contraction in cold temperatures

Answer 36

It’s slower in cold as enzymes denature, need to be around 37 degs
Muscles work better under tension (already stretched/contracted

Question 37

Briefly describe what an antagonist causes

Answer 37

A rightward shift in depression in maximum

Question 38

Describe what a bioassay involves

Answer 38

Use of live animal (in vivo) or tissue/cell (in vitro) to find biological activity of substances like hormones or drugs

Question 39

Describe the bioassay method

Answer 39

Drug activity measures living material, organ baths maintain live tissue by providing essential nutrients, pH, O2, warmth

Question 40

How do you measure changes in bioassay?

Answer 40

Tissue connected to force transducer under tension

Question 41

Describe the 2 methods used to form the response curve for bioassays

Answer 41

Adding each conc alone then washout (dose response curve)

Increasingly adding conc without washout btw drug addition (conc response curve)