Antagonists Flashcards Preview

BMS 242 Core Physiology and Pharmacology > Antagonists > Flashcards

Flashcards in Antagonists Deck (42)
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1

What are the 5 categories of antagonist action?

chemical, pharmacokinetic, physiological, non-competitive, competitive

2

Describe chemical antagonism

substances combine in solution so the effects of the active drug is lost

3

How does chemical antagonism cause loss of agonist

agonist is chemically altered

4

Give an example of chemical antagonist use

inactivation of heavy metal poison

5

How is the toxicity of heavy metals reduced

addition of a chelating agent

6

example of chelating agent

dimercaprol

7

Example of heavy metal poisons

mercury, lead and cadmium

8

What is the effect of pharmacokinetic antagonists

reduce the amount of drug absorbed, metabolised or excreted

9

How do pharmacokinetic antagonists decrease drug absorbtion

decrease absorption in the GI tract

10

What is an example of a drug reducing absorption

opiates reduce absorption by oral route

11

How do pharmacokinetic antagonists decrease absorption in the gut

inhibit gut motility

12

What does warfarin do

thins blood to prevent risk of strokes and heart attacks

13

How do pharmacokinetic antagonists change the excretion of an agonist

alter protein binding and filtration, alter urine pH and flow

14

Example of pharmacokinetic antagonist that changes the excretion of an agonist

diuretics

15

Describe physiological antagonism

interaction of two drugs with opposing actions in the body

16

Example of two interacting physiological antagonists

noradrenaline, histamine

17

What does histamine cause

vasodilation, lowers arterial pressure

18

What does noradrenaline cause

rise in arterial pressure - acts on blood vessels and heart

19

What does non competitive antagonist prevent

action of an agonist

20

What does non competitive antagonism block

step in process between receptor activation and response

21

TRUE or FALSE - non competitive antagonists compete with the agonist for the receptor site

false

22

What is a typical target for anti-hypertensive drugs

L type calcium channels

23

Example of a drug that targets L type calcium channels

Nifedipine

24

What is the effect of blocking L type calcium channels

reduces calcium signals, reduces muscle contraction

25

What works at the same site as the agonist

competitive antagonists

26

How can competitive antagonist effects be overcome

raising concentration of agonist

27

Describe the effect of increasing antagonist concentration on competitive antagonist concentration response curve

shifts the curve to the right, is parallel

28

What is the dose ratio

how many more times agonist is needed in the presence of an antagonist

29

What does the dose ratio give a measure of

shift of the dose response curve for given concentration of antagonist

30

What does the Schild analysis look at

relationship between dose ratio and concentration of antagonist added