2 Pharmacodynamics

Question 1

Pharmacodynamics

Answer 1

what the med does to the body

Question 2

Cellular Level

Answer 2

• where drugs exert primary action
• where receptors are (on or within cell)
• # of receptors is finite - can change

Question 3

Down Regulation

Answer 3

Body pulls out receptors

-ex.) too much stimulus, ephedrine

Question 4

Up Regulation

Answer 4

Body creates more receptors

-ex.) beta-blocker - cannot abruptly stop!

Question 5

When do receptor mediated responses plateau?

Answer 5

When receptors are saturated

Question 6

Affinity

Answer 6

strength of binding between drug and receptor

-stronger affinity can kick off lesser

Question 7

Dissociation Constant (Kp)

Answer 7

measure of a drugs affinity for a give receptor. The concentration of drug required in solution to achieve 50% occupancy of its receptors

Question 8

Agonist

Answer 8

drug which alters physiology of cell by binding to plasma membrane or intracellular receptor

• increases natural activity
• ex.) epi, alpha agonist

Question 9

Strong Agonist

Answer 9

causes maximal effects even though it may only occupy a small fraction of receptors

Question 10

Weak Agonist

Answer 10

must be bound to many more receptors than a strong agonist to have same effect

Question 11

Partial Agonist

Answer 11

fails to produce effects, even if all receptors are occupied

Question 12

Inverse Agonist

Answer 12

Not an antagonist. Binds to receptor site and causes opposite effect of agonist

• forces negative effect
  ex. ) H2 “antagonist”

Question 13

Antagonist

Answer 13

Inhibits or blocks action caused by agonist

Question 14

Competitive Antagonist

Answer 14

competes with agonist for receptors

ex. ) reversal agents
- can be overcome by high doses of agonist –> surmountable

Question 15

Noncompetitive Antagonist

Answer 15

can still block agonist, just through different site

• induces conformational change in receptor
• insurmountable - even high doses of agonist cannot overcome antagonism

Question 16

Irreversible Antagonism

Answer 16

Agent competes with agonists for agonist binding receptor and combine PERMANENTLY

Question 17

Efficacy

Answer 17

degree to which a drug is able to cause maximal effect

-can compare meds with different mechanisms

Question 18

Potency

Answer 18

amount of drug required to produce 50% of the maximal response that the drug is capable of causing - dose dependent

ex. ) need less morphine than codeine for pain relief - morphine is more potent
- can compare meds in same chemical class

Question 19

Drug Response Curves…drive home idea

Answer 19

all drugs have a plateau

-theory that opioids do not –> BS

Question 20

EC50

Answer 20

Efficacy Concentration 50%

-concentration of drug which induces a specific clinical effect in 50% of subjects

Question 21

LD50

Answer 21

Lethal Dose 50%

-concentration of drug which induces death in 50% of subjects

Question 22

Therapeutic Index

Answer 22

measure of the safety of a drug

LD50/EC50 = therapeutic index

Question 23

Margin of Safety

Answer 23

margin between therapeutic and lethal doses

Question 24

FDA Registries

Answer 24

• Used to track when medications are given anyways

- evaluated growth and development since studies are unethical

Question 25

REMS

Answer 25

Risk and Evaluation Mitigation Strategies

-for tracking high risk, dangerous meds

Question 26

Pregnancy Category A

Answer 26

Safest

-adequate, well controlled studies have been done

Question 27

Pregnancy Category B

Answer 27

Animal Studies do not show risk to fetus

Question 28

Pregnancy Category C

Answer 28

• Animal Studies have shown adverse effects, but no human studies
• eval risk vs benefit

Question 29

Pregnancy Category D

Answer 29

• Positive evidence for human fetal risk based on previous experience.
• risk vs benefits
  ex. ) seizure meds –> birth defects

Question 30

Pregnancy Category X

Answer 30

Animal and human studies show fetal demise

ex.) warfarin, ACE inhibitors

Question 31

Drug Interaction Addition

Answer 31

1+1=2

response is equal to parts

Question 32

Drug Interaction Syngergism

Answer 32

1+1=3
response is greater than parts
ex.) Abx

Question 33

Drug Interaction Potentiation

Answer 33

0+1=2

A drug with no effect enhances effect of second drug

Question 34

Drug Interaction Antagonism

Answer 34

Drug totally inhibits effect of another drug

Question 35

Altered Absorption

Answer 35

• inhibited absorption of other drugs across biologic membranes
  ex. ) anti-ulcer drugs coating stomach and blocking absorption

Question 36

Altered Metabolism

Answer 36

-P450 enzymes inhibited or reduced to yeild clinically significant interactions

Question 37

Plasma Protein Competition

Answer 37

drugs that bind to plasma may compete with other drugs for protein binding sites –> increase in unbound drug by competition

Question 38

Altered Excretion

Answer 38

-may act on kidneys to reduce excretion, yields a toxicity risk

Question 39

Tolerance

Answer 39

decrease response to a drug

metabolic or cellular (down-regulation)

Question 40

Dependence

Answer 40

• patient needs drug to function normally

- physical and/or psychological

Question 41

Abuse & Addiction

Answer 41

• not using drug for intended effect

- continued use despite negative effects

Question 42

Withdrawal

Answer 42

• when dependent person does not get drug

- often exact opposite of what drug is supposed to cause