EXAM #1: PHARMACODYNAMICS Flashcards Preview

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Flashcards in EXAM #1: PHARMACODYNAMICS Deck (53):
1

Generally, what is the pharmacodynamics?

"What the drug does to the body."

2

What are the five categories of receptors?

1) Intracellular receptors
2) Receptors with intrinsic enzyme activity
3) Receptors that directly associated with intracellular enzymes
4) Ligand-gated ion channels
5) 7-membrane spanning receptors (GPRC)

3

What type of ligands bind intracellular receptors?

LIPOPHILLIC ligands e.g.
- Steroids
- Thyroid hormone
- Fat-soluble vitamins

4

What is the general consequence of ligand binding with an intracellular receptor?

Change in gene transcription

5

Describe the structure of a receptor with intrinsic enzymatic activity.

- Single membrane spanning domain
- Extracellular domain binds ligand
- Intracellular domain contains enzymatic activity

6

What is the difference between a receptor with intrinsic enzymatic activity and a receptor that directly associates with intracellular enzymes?

Transmembrane domain associated with an enzyme instead of containing intrinsic activity itself

7

Describe the general structure of a ligand-gated receptor. What types of substances typically interact with ligand-gated channels?

- Multimeric complex of several transmembrane domains that form a barrel in the membrane
- Hormones and neurotransmitters

8

What is a 7MSR? What types of signals are propagated through a 7MSR?

"7 Membrane Spanning Receptors" that mediated:
- G-protein coupled signals
- G-protein independent signals

9

What are estrogen receptors and Vitamin A receptors examples of?

Intracellular receptors

10

What are epidermal growth factor receptor (EGFR), insulin receptor (IR), and transforming growth factor receptor (TGF-BR) examples of?

Receptor with intrinsic enzymatic activity

11

What receptor type associates with kinases and proteases including IL-3R, erythropoetin receptor, and the leptin receptor?

Receptors that directly associated with intracellular receptors

12

What type of receptor is the nicotinic acetylcholine receptor (NAChR)?

Ligand-gated

13

What type of receptor are the B-adrenergic, odorant, rhodopsin, frizzled, and smoothened receptors?

7MSR or G-protein coupled

14

What is a typical stimulus for receptor downregulation?

Continued simulation of the receptor

15

What is a typical stimulus for receptor upregulation?

Continued exposure to an inhibitor

16

What is Kd?

- Dissociation constant
- Ligand concentration at a point at which 50% of receptors are bound

17

Write the two different equations for Kd.

N/A

18

Draw and label a graph of drug concentration (C) vs Receptor-bound drug (B). Be sure to include Kd and Bmax.

N/A

19

What does Kd represent?

Affinity of a ligand for a receptor

20

What does a small Kd indicate? What does a large Kd indicate?

Small Kd= high affinity
Large Kd= low affinity

21

Example from powerpoint.

IP

22

Draw the dose-response curve on a drug concentration (C) vs. drug effect (E) graph. Be sure to include EC50 and Emax.

N/A

23

What is the EC50?

Concentration of drug that produces half-maximal effect.

24

What is potency a comparison of? What is potency conceptually?

- EC50
- Potency is a measurement of relative affinity and effectiveness of two or more drugs.

*****A drug with a LOWER EC50 is MORE potent.

25

What is efficacy a comparison of? What is efficacy conceptually?

- Emax
- Efficacy is the maximal effect a drug can induce.

*****A drug with a higher maximal effect is more efficacious.

26

If drug A has a lower EC50 than drug B, what does this indicate about drug B?

Drug A is MORE potent

27

Are potency and efficacy independent or dependent on each other?

INDEPENDENT

28

What is an agonist?

A ligand that binds to a receptor AND produces a response

*****Response can be molecular, cellular, or physiological

29

What is an antagnoist?

A ligand that binds to a receptor and INHIBITS the response produced by the agonist

30

What is the difference between a competitive and noncompetitive antagonist?

Competitive= agonist and antagonist compete for the same binding site

Noncompetitive= agonist and antagonist bind at DIFFERENT sites

31

How does a competitive antagonist alter the dose-response curve?

- Shift in the EC50 to the RIGHT
- Emax is stall achievable

32

How does a noncompetitive antagonist alter the dose-response curve?

Decrease in Emax

****Note that the agnoist's affinity (EC50) for the receptor may not be changed by the noncompetitive antagonist

33

How can you overcome the effects of a competitive antagonist?

Administer more agonist

34

What is a partial agonist?

- Drug that produces a lower than maximal response compared to the agonist i.e. lower Emax/ efficacy
- Binding of the partial agonist also DECREASES binding of the agonist

*****Note that the partial agonist evokes a partial response, whereas a noncompetitive antagonist inhibits a response. BOTH decrease Emax.

35

How can a partial agonist be used clinically?

- Administration of a partial agonist decreases binding of the full agonist
- A partial agonist can be given to decrease the effect of an endogenous substance (full agonist)

E.g. epinephrine as the endogenous substance, drug as a partial agonist--blunts the normal physiologic response

36

See ppt. example question on "dose response curve."

B is most potent (lower ED50)

A, C, and D are equally efficacious (but differ in potency)

37

See ppt. example question on "dose response curve 2.0"

B and C are competitive inhibitors

D and E are non-competitive inhibitors

38

What is a quantal dose response curve?

Graph of dose (x) vs. % individuals responding (y)

39

What is the quantal dose response curve used for?

Describing the:
- Effective dose
- Toxic dose
- Lethal dose

40

What is the ED50?

"Median Effective Dose"

- Dose at which 50% of individuals exhibit a specific quantal response

41

What is the TD50?

"Median Toxic Dose"

- Dose at which a specific toxic effect occurs within 50% of the individuals tested

*****Note that this is typically further to the right on the quantal dose-effect curve than the ED50

42

What is the LD50?

"Median Lethal Dose"

- Dose that is lethal for 50% of individuals tested

43

What is the TI? What is the TI an indication of?

TI= Therapeutic Index

*****The TI is a measure of SAFETY*****

44

What is the equation for the TI?

TD50/ED50

45

Is a drug with a large TI, more safe or less safe than a drug with a small TI?

Greater TI= MORE SAFE

46

Answer the case presentation example on TI?

A= 4,000/100= 40
*Safer

B= 1,000/200= 5

47

Draw a quantal dose-effect curve representing the TI examples from the ppt.

N/A

48

What is tolerance?

Decreased drug response following repeated administration

49

What is sensitization?

"Reverse tolerance"

- Increase in drug response following repeated administration

50

What does tolerance look like on a dose-response curve? Sensitization?

Tolerance= shift to the right

Sensitization= shift to the left

51

What are the causes of tolerance?

1) Phamacokinetic changes i.e. a change in metabolism
2) Change in pharmacodynamic parameters i.e. downregulation/ decrease in receptor number
3) Behavioral changes i.e. patient predicts response to drug and mentally compensates for it

52

What is the additive effect of multi-drug therapy?

Two drugs given together produce an effect consistent with the combined potency of the drugs

53

What is the synergistic effect of multi-drug therapy?

Two drugs produce a response that is GREATER than the sum of the agent's potency

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