Pharmacodynamics

Question 1

What is a receptor?

Answer 1

A macromolecule whos biological function changes when a drug binds to it

Many drugs bind to receptors but do not cause change, competitive inhibi

Question 2

What is affininty?

Answer 2

Measure of the propensity of a drug to bind receptor.

Question 3

What is are the events that get triggered from receptor binding called?

Answer 3

Signal transduction

Question 4

What are the types of bonds between drug and receptor?

Answer 4

Van Der Waals
Ionic
Covalent Interactions

Mulitple Bonds and Interactions are used

Question 5

What happens if we put two drugs acting at same receptor?

Answer 5

They will compete for transient binding of the receptor.

Higher concentration drug has greater chance of binding.

Question 6

Know this Slide

Answer 6

Question 7

How do we measure or quantify a drug receptor interaction?

Answer 7

Dose - Response Curve

Question 8

What is the EC50 Value?

Answer 8

Concentration/Dose of a drug that produces %50 max response.

Question 9

What are features of a Log dose - response graph?

Answer 9

• Sigmoid/Linear Curve
• Compressed Dose Scale
• Proportionate doses at equal intervals
• Straightens line
• Easier to analyze

Question 10

What is Emax and what does it measure?

Answer 10

Maximal effect from a drug. It measures efficacy of a drug

Efficacy is ability of bound drug to change receptor to make an effect.

Some bind receptors but do not produce effect.

Question 11

What does the Kd Value mean?

Answer 11

Concentration of a drug that occupies 50% of the total number of receptors at equilibirum.

Question 12

Why is the Kd50 Value different from the EC50

Answer 12

There are more receptors in the body than needed to produce maximal response. Do not need to activate 50% of receptors to achieve 50% maximal response.

Question 13

What is an agonist?

Answer 13

Drug which binds to the receptor and produces an effect.

Question 14

What is a partial agnostic?

Answer 14

Has an affinity for a receptor but lower efficacy and lower Emax than a full agonist.

Question 15

What is an antagonist?

Answer 15

a drug which binds to receptor but has no efficacy(produces no effect) but competes for binding against other ligands.

2 Types: Competitive (reversible)
Noncompetitive (irreversible)

Question 16

Why is a partial agonist useful?

Answer 16

partial agonist acts as an antagonsit in the presence of a full agonist. Blocks full effect

Question 17

What are 2 clinical examples of a partial agonist being useful?

Answer 17

Example: Buphrenorphine as an opioid analgesic instead of morphine. (Less likely overdose, lower level of dependance, lower risk of abusing it)

Example: Pindolol for High Blood Pressure and Abnormal heart Rythms. Noraepinephrine(Full Agnonist) from overactive sympathic nervous system. Partial Agonist Pindolol competitevly binds reducing effects.

B1 Andregenic Receptors

Question 18

Can the usual effect of an agonist be achieved if in the presence of a reversible competitive antagonist?

Answer 18

Yes, if the dose of Agonist is increased

Achieve a Rightward shift of Dose - Response Graph

Question 19

Can a higher dose of agonist achieve maximal effect in the presence of a non competitive irreversible antagonist?

Answer 19

NO

Question 20

What happens to the Emax of an agonist in the presence of a non competitive antagonist?

Answer 20

E max Depresses cannot reach maximum effect.

If dose of antagonist keeps increasing - Can get E max to 0

Question 21

What is an inverse agonist?

Answer 21

Some receptors have intrinsic activity when nothing is bound, when ligand binds the activity is reduced.

Question 22

What is it called when ligand B binding potentiates the response of agonist A.

Answer 22

Allosteric Interaction

Question 23

Explain the Allosteric effects on GABA.

Answer 23

Benzodiazepine drugs potentiate the response to gama aminobutyric acid(GABA) when they bind to the GABAA.

GABA involved in Inhibition Sedation - it is a neurotransmitter

When GABA binding is effected it causes chloride channels to open for longer.

Question 24

Remember this

Answer 24

Question 25

Clinical Revelance of Different types of Antagonism?

Answer 25

Easier to treat overdose and poisonous by a competitive reversible system.

Harder to treat with irreversible system.

Question 26

What does a quantal dose curve mean?

Answer 26

indicates sensitivity of a given population to a drug.

Question 27

What is frequency distribution?

Answer 27

Each bar shows number of people responding to that specific dose.

Question 28

What is Cumulative Frequency?

Answer 28

Each bar shows the number of people responding to that dose and all the lower ones.

Question 29

What is the TD 50

Answer 29

Concentration that is toxic to 50% of the population.

Question 30

What is the ED 50

Answer 30

Concentration of the drug that 50% of the population respond to,

Question 31

What is the LD 50

Answer 31

Lethal Dose in 50% of the population.

Question 32

What is the Therapeutic Window

Answer 32

It is the difference between the minimum effective doses for a desired response and an adverse response.

Question 33

What are the 4 types of signal transduction mechanisms?

Answer 33

G- Protein coupled receptor system - Half of all drugs work through this.

Ion channel Receptors

Enzyme as receptors

Nuclear Receptors - For Hormones and Lipid Soluble Drugs - Bind in cytosol.

2,1,3,4 In order Fastest to Slowest