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Flashcards in general principles lect 1 Deck (38):
1

pharmacodynamics

biochemical and physiological effects and mechanisms (what drugs do to the body)

2

pharmacokinetics

absorption, distribution, metabolism, and elimination of drugs (what body does to drugs)

3

measures the ability of a drug to bind to a receptora

affinity

4

Kd

equilibrium dissociation constant: concentration of free drug when binding is at 50%

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relationship between Kd and affinity

the lower the Kd, the higher the affinity

6

efficacy (intrinsic activity)

measure of biological response resulting from binding of a drug - determines maximal response that can be obtained with a drug

7

potency

dose (amount of drug) required to produce a desired effect

8

EC50

concentration required for half-maximal effect

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relationship between EC50 and potency

lower the EC50 the more potent the drug

10

binds to receptor and initiates a response

agonist (full vs partial)

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binds to receptor but does not initiate a response

antagonist (inhibits response to an agonist) -competitive vs non-competitive

12

binds to different receptor site than agonist and alters the reponse to agonist

allosteric activators and inhibitors

13

interaction between drug and receptor is reversible unless they are bound by what kind of bond

covalent

14

at drug-receptor equilibrium, how many receptors are bound?

half of the receptors are bound; half are free

15

efficacy (alpha; intrinsic activity) is the ability of a drug to initiate a response; if there is a 100% response, Alpha = ?; if there is a 0% reponse, alpha = ?

1; 0

16

what type of agonist have affinity and intrinsic activity (alpha = 1)

full agonist

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what type of agonist have affinity but no intrinsic activity (alpha = 0)

antagonist

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what type of agonist have affinity but lower intrinsic activity (0

partial agonist

19

What Emax?

Emax: response produced will increase with increasing drug concentration until a maximal response is reached

20

what is Emax a function of

- amt of drug - ability to evoke a response - the number of available receptors

21

plotting %biological effect vs log[drug] gives what types of curve. what effect does this have on theraputic effect and toxicity

sigmoid curve - expands the scale at low concentrations where the response increases rapidly (theraputic effect) and contracts at high concentrations where the response is not changing as quickly (toxicity)

22

in graded dose-response curves, what does the slope of the curve indicate

how rapidly the response changes when the dose in increased. Steep slopes are risky (small theraputic window)

23

What do quantal dose-response curves measure

frequency with which a response will occur to a given dose within a population - "all or none effect" - frequency of response is measured - determines doses that produce therapeutic and lethal effects

24

How is therapeutic ratio measured in humans

TD50 (toxic dose)/ED50: (LD50= dose that is toxic in 50% of population that recieves the drug). ex: if TR = 4 and 100mg is effective in 50% of population; then 400mg is lethal in 50% of population

 

* animal studies can use LD50: lethal dose

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Margin of safety

= LD1/ED99 - higher the margin of safety, safer the drug

26

how does number of receptors affect sensitivity of a cell to a drug

the more receptors, the more sensitive a cell is to a drug

27

when do spare receptors exist

when it is possible to elicit a maximum biological response without occupying all of the available receptors

28

when spare receptors exist, the concentration-response curve (ED50) is shifted to what side

shifted to smaller concentrations-> to the left

29

what is the relationship between EC50 and Kd when there are spare receptors

EC50 is lower than Kd * maximal response still produced due to amplification of the cell signaling mechanism

30

clinical implications of spare receptors

use a lower dose

31

how is potency determined on a dose response curve

postion along the x-axis; a drug is more potent if a curve is located near the left side of the x-axis; a drug is less potent is a curve is located near the right side of the x-axis

 

ex: Drug X is more potent than Drug Y

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32

Drug + receptor -> [DR]; what is the rate constant for DR association

K1

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[DR] -> Drug + receptor; what is the rate constant for DR dissociation

K2

34

What is Kd in terms of K1 and K2

Kd=K2/K1; if Kd is low; dissociation is slow and binding affinity is high and vice versa

35

in most cases, ED50 and Kd are the same; name a case in which they aren't

spare receptors; ED50 is lower than Kd

36

drugs that act on the same receptor but have a lower affinity for the receptor will show what ED50 compared to a drug that has a high affinity for a receptor

lower ED50 

37

threshold dose

dose below which no response is observed 

38

what is theraputic ratio

range of concentrations in which likelihood of efficacy is high and the probability of adverse effects is low