02.1 Pharmacodynamics

Question 1

What does “selective” mean in terms of drugs?

Answer 1

Drug acts at a given site/target

Question 2

What does “specific” mean in terms of drugs?

Answer 2

Drug acts at a specific receptor (e.g. B2)

Question 3

What are the two main types of drugs that act at receptors?

Answer 3

Agonist

Antagonist (full/partial)

Question 4

Define affinity

Answer 4

Tendancy of a drug to bind

Question 5

Define efficacy

Answer 5

Maximal effect of a drug when bound to a receptor

Question 6

Define potency

Answer 6

EC50 or IC50

Question 7

What is the therapeutic index?

Answer 7

LD50/ED50

Question 8

What is a pharmacodynamic DDI?

Answer 8

Where drugs act at the same receptor

Question 9

Give an example of how a drug can reduce absorption of another drug

Answer 9

Laxatives increasing gut motility will reduce the amount of other drugs absorbed in the intestines

Question 10

Give an example of how a drug can alter the distribution of another drug

Answer 10

By displacing another drug from a protein/lipid binding site

Question 11

Give an example of how a drug can alter the metabolism of other drugs

Answer 11

Induction/inhibition of CYP enzymes

Question 12

Give an example of how a drug can alter the excretion of another drug

Answer 12

NSAIDs reducing GFR and renal elimination

Protein binding prevents kidney excretion also

Question 13

What are some foods that can interact with drugs?

Answer 13

Grapefruit juice

Cranberry juice

Question 14

What is an on target ADR?

Answer 14

Response at the same site (e.g. antihypertensives causing hypotension)

Question 15

What is an off target ADR?

Answer 15

Drugs causing a response at a secondary site