08.13 Welch

Question 1

EC 50

Answer 1

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

Question 2

what are the types of dose-response curves?

Answer 2

-Graded and Quantal

Question 3

Graded dose-response curve

Answer 3

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

Question 4

Quantal dose-response curve

Answer 4

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

Question 5

what is potency determined by?

Answer 5

the affinity of the receptor for the drug

-potency affects drug dosage

Question 6

ED 50

Answer 6

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

Question 7

efficacy

Answer 7

• 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

Question 8

difference between a full agonist and a partial agonist

Answer 8

• 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

Question 9

Therapeutic Index: TI=

Answer 9

TI=LD50/ED50

• LD50= the median lethal dose of a drug in animals
• the higher the TI, the safer the drug is

Question 10

LD50

Answer 10

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

Question 11

TD50

Answer 11

The median toxic dose

-done on humans

Question 12

CSF

Answer 12

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

Question 13

antangonist

Answer 13

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

Question 14

competitive reversible antagonist

• E max
• Shift?

Answer 14

• 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

Question 15

Competitive irreversible antagonist

-how can it be overcome

Answer 15

• 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

Question 16

Physiologic (functional) antagonist

Answer 16

-two agonist working at different receptors that have opposing actions

Question 17

Chemical antagonist

Answer 17

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

Question 18

Pharmacokinetic antagonist

Answer 18

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