Introduction to Pharmacodynamics

Question 1

What are the four main kinds of proteins that are the primary drug targets?

Answer 1

Receptors, Enzymes, Transporters/carrier molecules, Ion channels

Question 2

How can drugs interact with enzymes, transporters, or ion channels?

Answer 2

Drugs can change their activity by binding to them and altering their function.

Question 3

Why do drugs need selectivity for the target?

Answer 3

To minimize off-target effects and enhance therapeutic efficacy.

Question 4

How is drug binding to a receptor described?

Answer 4

It is described by the drug’s affinity, which indicates how tightly the drug binds.

Question 5

What is the relationship between drug concentration and response called?

Answer 5

Dose/concentration-response relationship

Question 6

What is the difference between an agonist and an antagonist?

Answer 6

Agonists activate receptors, while antagonists bind without activating them.

Question 7

How can you differentiate between a competitive reversible and irreversible antagonist?

Answer 7

Reversible antagonists bind non-covalently and can be displaced by agonists; irreversible antagonists bind covalently and reduce receptor availability.

Question 8

Define affinity in pharmacodynamics.

Answer 8

A measure of how tightly a drug binds to the receptor.

Question 9

What is the dissociation constant (KD)?

Answer 9

The concentration of drug when 50% of receptors are occupied.

Question 10

What does a higher KD indicate about a drug’s affinity?

Answer 10

Lower affinity; more drug is required to occupy the receptors.

Question 11

Define potency in pharmacodynamics.

Answer 11

A measure of how much drug is required to produce a particular effect.

Question 12

What does EC50 stand for?

Answer 12

The effective concentration of a drug that produces 50% of the maximal response.

Question 13

What is efficacy in the context of drug action?

Answer 13

The ability of a drug to produce a response.

Question 14

What characterizes a full agonist?

Answer 14

Elicits the maximum tissue response.

Question 15

What is a partial agonist?

Answer 15

A drug that binds with affinity but does not produce a maximal response.

Question 16

What is an inverse agonist?

Answer 16

A drug that binds to receptors to decrease basal receptor activity.

Question 17

What is unique about antagonists?

Answer 17

They have affinity but no intrinsic efficacy.

Question 18

What is reversible competitive antagonism?

Answer 18

When an antagonist competes with an agonist for the same binding site.

Question 19

What defines irreversible competitive antagonism?

Answer 19

Covalent binding to the receptor’s orthosteric site, making it non-surmountable.

Question 20

What are allosteric modulators?

Answer 20

Drugs that bind to a site distinct from the endogenous ligand to alter receptor interaction.

Question 21

What is chemical antagonism?

Answer 21

When two substances combine in solution to neutralize each other.

Question 22

What is pharmacokinetic antagonism?

Answer 22

Reduction of drug concentration at the active site.

Question 23

What is physiological antagonism?

Answer 23

When two drugs with opposing actions cancel each other out.

Question 24

What are ligand-gated ion channels?

Answer 24

Ion channels that open in response to drug/ligand binding.

Question 25

What are voltage-gated ion channels?

Answer 25

Ion channels that open in response to changes in membrane potential.

Question 26

What is an enzyme?

Answer 26

A biological catalyst that speeds up specific chemical reactions.

Question 27

What are the two types of enzyme inhibition?

Answer 27

Competitive and non-competitive inhibition.

Question 28

What is a transporter?

Answer 28

Proteins that transport ions and small molecules across membranes.

Question 29

What is the role of P-glycoprotein in pharmacology?

Answer 29

It exports drugs from the cytosol to outside the cell, often conferring drug resistance.

Question 30

What is desensitization in the context of drug action?

Answer 30

A reduction in drug effect occurring within minutes.

Question 31

What is tolerance in pharmacology?

Answer 31

A reduction in drug effect over hours to days.

Question 32

What is resistance in pharmacology?

Answer 32

Loss of sensitivity to cytotoxic or antimicrobial drugs.

Question 33

What is desensitisation in pharmacology?

Answer 33

Drug effect reduces in a few minutes ## Footnote Desensitisation refers to the rapid decrease in drug effect following its continuous or repeated administration.

Question 34

What is tolerance in pharmacology?

Answer 34

Drug effect reduces over hours to days ## Footnote Tolerance occurs when the body becomes less responsive to a drug after prolonged use.

Question 35

What is resistance in pharmacology?

Answer 35

Loss of sensitivity to cytotoxic/antimicrobial drugs ## Footnote Resistance is particularly relevant in the context of infections and cancer treatments.

Question 36

What are the mechanisms behind desensitisation, tolerance, and resistance?

Answer 36

Receptor phosphorylation, receptor internalisation, intracellular feedback loops, drug metabolism, physiological adaptation ## Footnote These mechanisms can contribute to the diminished effectiveness of drugs over time.

Question 37

What is affinity in pharmacology?

Answer 37

A measure of the concentration of drug required to occupy 50% of receptors ## Footnote Affinity is crucial in determining how effectively a drug can bind to its target.

Question 38

What does EC50 represent?

Answer 38

Effective concentration of an agonist that produces 50% of the maximal response ## Footnote EC50 is a key parameter in assessing the potency of a drug.

Question 39

What is the difference between an agonist and an antagonist?

Answer 39

Agonist activates the receptor; antagonist binds but does not activate ## Footnote Agonists have efficacy, while antagonists do not.

Question 40

What are full agonists and partial agonists?

Answer 40

Full agonists elicit maximum tissue response; partial agonists produce less than maximum response ## Footnote Partial agonists can occupy receptors but do not fully activate them.

Question 41

What defines a competitive reversible antagonist?

Answer 41

Can be overcome by increasing the dose of agonist ## Footnote This type of antagonist competes with the agonist for binding to the same site on the receptor.

Question 42

What is irreversible competitive antagonism?

Answer 42

Drug covalently binds to the receptor’s orthosteric site ## Footnote This type of antagonism is not surmountable, reducing the number of receptors available for agonist binding.

Question 43

What are allosteric modulators?

Answer 43

Drugs that bind to sites other than the orthosteric site and modify receptor activity ## Footnote Allosteric modulators can enhance or inhibit the effect of the orthosteric ligand.

Question 44

What is the role of transporters in pharmacology?

Answer 44

Transport ions and small molecules across membranes ## Footnote Transporters are critical for the uptake and distribution of drugs within the body.

Question 45

What is a non-competitive antagonist?

Answer 45

Blocks receptor response downstream or through non-competitive blockage ## Footnote Non-competitive antagonists may inhibit the effect of an agonist without directly competing for the same binding site.

Question 46

What is pharmacokinetic antagonism?

Answer 46

Reduces the concentration of the drug at the active site ## Footnote This can occur through various means, such as altered absorption or metabolism.

Question 47

What is the significance of P-glycoprotein in pharmacology?

Answer 47

Exports drugs from the cytosol to outside the cell, affecting drug bioavailability ## Footnote High expression in cancer cells contributes to multidrug resistance.

Question 48

What is the definition of pharmacodynamics?

Answer 48

The relationship between drug concentration at the site of action and the resulting effect ## Footnote Understanding pharmacodynamics is essential for effective drug design and therapy.

Question 49

What is a ligand-gated ion channel?

Answer 49

A type of receptor that opens following drug/ligand binding ## Footnote These channels are critical for mediating rapid cellular responses.

Question 50

What is an enzyme?

Answer 50

A biological catalyst that speeds up the rate of a specific chemical reaction ## Footnote Enzymes play a crucial role in metabolic processes and drug interactions.

Question 51

What is the role of cyclooxygenase (COX) in pharmacology?

Answer 51

Converts arachidonic acid to prostaglandins; target of aspirin ## Footnote Inhibiting COX reduces inflammation and pain.

Question 52

What is the function of neurotransmitter reuptake transporters?

Answer 52

Transport neurotransmitters back into nerve terminals ## Footnote These transporters are targeted by various antidepressants.

Question 53

What are physiological antagonists?

Answer 53

Two drugs whose opposing actions cancel each other out ## Footnote For example, histamine-induced vasodilation can be countered by adrenaline-induced vasoconstriction.

Question 54

What is receptor internalisation?

Answer 54

The process by which receptors are removed from the cell surface ## Footnote This can contribute to desensitisation and tolerance.