08.13 Welch Flashcards Preview

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Flashcards in 08.13 Welch Deck (18):
1

EC 50

Effective concentration 50, the point at which there is 50% of maximal effect, it is not determined by dosage

2

what are the types of dose-response curves?

-Graded and Quantal

3

Graded dose-response curve

-measured in a single biologic unit
-continuous scale (incr. dose leads to incr effect)
-relates dose to intensity of effect

4

Quantal dose-response curve

-population studies
-all-or-none pharmacologic effect
-relates dose to frequency of effect

5

what is potency determined by?

the affinity of the receptor for the drug
-potency affects drug dosage

6

ED 50

-Effective dose 50
-the dose that produced an effect in 50% of ppl
-same as ec 50?

7

efficacy

-the maximal effect that can be produced by a drug
-determined mainly by the properties of the drug and its receptor-effector system
-important clinical measure
-partial agonist have lower maximal efficacy than full agonists

8

difference between a full agonist and a partial agonist

-the full agonist can induce a conformational change in the receptor leading to a maximal effect.
-partial agonists can induce some degree of receptor activation, but not of sufficient magnitude for a maximal response

9

Therapeutic Index: TI=

TI=LD50/ED50
*LD50= the median lethal dose of a drug in animals
-the higher the TI, the safer the drug is

10

LD50

the median lethal dose of a drug in animals
(lethal dose in 50% of population)
TI=LD50/ED50

11

TD50

The median toxic dose
-done on humans

12

CSF

-Certain Safety factor
-used to determine a therapeutic window
CSF=LD1/ED99
*TI compares midpoints, CSF compares endpoints

13

antangonist

when it binds, it doesn't elicit a response, but it blocks (or reduces) agonists from binding, thus there is no net effect
-they have affinity, but no efficacy for their receptors

14

competitive reversible antagonist
-E max
-Shift?

-inhibition can be overcome by increasing agonist concentration
-no significant change in E max
-the dose-response curve will shift to the right, but slope is the same
-primarily affects agonist potency

15

Competitive irreversible antagonist
-how can it be overcome

-antagonist forms covalent bond, thus dissociates slowly or not at all
-inhibition cannot be overcome
-maximal response is depressed
-DR curve will be shifted to the right and the slope will be reduced (usually)
-potency may or may not be affected
-the only way to overcome, is synthesis of new receptors

16

Physiologic (functional) antagonist

-two agonist working at different receptors that have opposing actions

17

Chemical antagonist

-when two substances combine in solution and the active drug is lost

18

Pharmacokinetic antagonist

-effectively reduce the concentration of the active drug at its site of action