Pharm - Pharmacokinetics/-dynamics (Receptor binding & Therapeutic measures)

Question 1

Define Efficacy.

Answer 1

Maximal effect a drug can produce.

Question 2

What are 4 examples of high-efficacy drug classes?

Answer 2

High-efficacy drug classes are (1) analgesic (pain) medications (2) antibiotics (3) antihistamines (4) decongestants

Question 3

Contrast partial and full agonists in terms of efficacy.

Answer 3

Partial agonists have less efficacy than full agonists

Question 4

Define Potency.

Answer 4

Amount of drug needed for a given effect

Question 5

What is the relationship between potency and affinity for receptor?

Answer 5

Increase potency, Increase affinity for receptor

Question 6

What are 3 examples of highly potent drug classes?

Answer 6

Highly potent drug classes include (1) chemotherapeutic (cancer) drugs (2) antihypertensive (blood pressure) drugs (3) lipid-lowering (cholesterol) drugs

Question 7

Draw graphs demonstrating Drug X having greater efficacy and being more potent than Drug Y, but Drug Y being able to reach Drug X’s effect with greater dosage.

Answer 7

See p. 241 in First Aid 2014 for graphs

Question 8

Draw a graph depicting the effect of a competitive antagonist on agonist dose and percent maximal effect.

Answer 8

See p. 242 in First Aid 2014 for graph on left

Question 9

Draw a graph depicting the effect of a noncompetitive antagonist on agonist dose and percent maximal effect.

Answer 9

See p. 242 in First Aid 2014 for middle graph

Question 10

Draw a graph depicting the dose and maximal effect of full versus partial agonist.

Answer 10

See p. 242 in First Aid 2014 for graph on right

Question 11

What is the effect of a competitive antagonist? Can it be overcome?

Answer 11

Shifts curve to right (decreasing potency), no change in efficacy. Can be overcome by increasing the concentration of agonist substrate.

Question 12

What is the effect of a noncompetitive antagonist? Can it be overcome? What other type of antagonist shares these properties?

Answer 12

Shifts curve down (decreasing efficacy). Cannot be overcome by the increased agonist substrate concentration; Irreversible competitive antagonist

Question 13

How do partial agonists contrast with full agonist? What kind of variable is potency?

Answer 13

Acts at same site as full agonists, but with lower maximal effect (decreased efficacy); Potency is an independent variable

Question 14

What is an example of competitive antagonist, and on what receptor does it act?

Answer 14

Diazepam + Flumazenil (competitive antagonist) on GABA receptor

Question 15

What is an example of noncompetitive antagonist, and on what receptor does it act?

Answer 15

Glutamate + Ketamine (noncompetitive antagonist) on NMDA receptors

Question 16

What is an example of irreversible competitive antagonist, and on what receptor does it act?

Answer 16

Norepinephrine + Phenoxybenzamine (irreversible competitive antagonist) on alpha-receptors

Question 17

What is an example of full versus partial agonist, and on what receptor does it act?

Answer 17

Morphine vs. Buprenorphine (partial agonist) at opioid mu-receptors.

Question 18

What is the clinical use of therapeutic index?

Answer 18

Measurement of drug safety

Question 19

What is the equation for therapeutic index?

Answer 19

TD 50 / ED 50 = median toxic dose / median effective dose; Think: “TITE: Therapeutic index = TD 50 / ED 50”

Question 20

What is the therapeutic window?

Answer 20

Therapeutic window - measure of clinical drug effectiveness for a patient

Question 21

Do safer drugs have lower or higher TI values?

Answer 21

Safer drugs have higher TI values

Question 22

What are 4 examples of drugs with low TI values?

Answer 22

Examples of drugs with low TI values include (1) digoxin (2) lithium (3) theophylline (4) warfarin

Question 23

What often replaces TD 50 in animal studies?

Answer 23

LD 50 (lethal median dose) often replaces TD 50 in animal studies.

Question 24

Draw a graph of (x-axis: log (drug concentration), y-axis: % of patients responding), depicting and labeling the following: (1) efficacy (2) therapeutic index (3) therapeutic window (4) toxicity (5) ED 50 = median effective dose (6) TD 50 = median toxic dose.

Answer 24

See p. 242 in First Aid 2014 for graph at bottom of page