Module 8 Drug Receptor Interactions

Question 1

Simple Occupancy Theory

Answer 1

• Intensity of drug response proportional to quantity of receptors
• Maximal response occurs when all receptors occupied

Question 2

Modified Occupancy Theory

Answer 2

• Response intensity proportional to occupied receptors
• 2 drugs on same receptor can have different binding strengths
• 2 drugs on same receptor can have different activation abilities

Question 3

Affinity

Answer 3

• Attraction of drug to receptor
• Primary determinant of drug potency

Question 4

Intrinsic Activity

Answer 4

• Ability of drug to activate receptor
• Reflected in efficacy

Question 5

Interaction Classifications

Answer 5

• Agonist
• Antagonists
• Partial agonist

Question 6

Agonist Definition

Answer 6

• Molecule binds to receptor causing activation
• Mimic action of endogenous ligands

Question 7

Antagonist Definition

Answer 7

• Molecules bind to receptor causing no activation

Question 8

Partial Agonist Definition

Answer 8

• Molecules bind to receptor, minimal activation ability

Question 9

Agonist Characteristics

Answer 9

• Includes hormones & neurotransmitters (endogenous)
• Affinity
• Intrinsic activity
• Increase/decrease physiological response

Question 10

Partial Agonist Characteristics

Answer 10

• Minimal/moderate intrinsic activity
• Act as antagonists, block full agonist binding

Question 11

Antagonist Characteristics

Answer 11

• Affinity
• Prevent endogenous binding
• Require presence of agonist
• Treat drug overdose

Question 12

Antagonist Examples

Answer 12

• Beta blockers
• Antihistamines
• Gastric acid reducers
• Opioid receptor blockers

Question 13

Antagonist Types

Answer 13

• Competitive
• Irreversible
• Allosteric

Question 14

Competitive Antagonists

Answer 14

• Binding at same site as agonist
• Reversible
• Equal affinity of antagonist & agonist, higher conc wins binding site
• Effects overpowered by increasing agonist conc

Question 15

Irreversible Antagonists

Answer 15

• Binding at same site as agonist
• Irreversible
• Response intensity dependant on agonist bound to receptor
• Effects last until receptor replaced

Question 16

Allosteric Antagonists

Answer 16

• Binding at different site than agonist
• Changes receptor conformation
• Reversible
• Non-competitive, bind to different site than agonist
• Agonists can’t overcome effects
• Decrease maximal response of agonist

Question 17

Regulation of Cell Surface

Answer 17

• Receptor quantity changes with drug exposure
• Majority of drug reactions dependent on cell surface receptor

Question 18

Drug Tolerance Types

Answer 18

• Desensitization
• Metabolic tolerance
• Tachyphylaxis

Question 19

Desensitization

Answer 19

• Continuous exposure to agonist
• Internalize/destroy receptor
• Decreases cell surface receptors & drug effects

Question 20

Metabolic Tolerance

Answer 20

• Continuous exposure to drug
• Induction of metabolizing enzymes
• Decrease plasma drug conc

Question 21

Tachyphylaxis

Answer 21

• Rapid decrease in drug response
• Drug free period between administrations

Question 22

Receptor Upregulation

Answer 22

• Continuous exposure to antagonist
• Cell becomes hypersensitive
• Synthesis of more receptors
• Increasing response