Pharmacodynamics Flashcards Preview

Spring 2020 - Pharmacology 1 > Pharmacodynamics > Flashcards

Flashcards in Pharmacodynamics Deck (50)
Loading flashcards...
1

Pharmacodynamics

What Meds do to the Body

  • Most drugs bind to cell receptors where they initiate reactions that alter cell's physiology
  • Some of a drug's molecules will find target cell, some distributed, metabolized, and excreted
  • Drugs exert primary action at cell level

2

Medication Actions

Pharmacology at 

cell level, organism level, and population level

3

Drug Receptors

  • Proteins/Glycoproteins on cell surface, organelle inside cell, or cytoplasm
  • Finite mumber - response plateaud once saturated
  • Downregulation/Upregulation

4

What happens after a drug is bound to the receptor?

  • Ion channel opens/closes
  • Activate biochemical messengers, second messengers (cAMP, cGMP, C++, Inositol Phosphates) - each signal that passes amplified
  • Inhibit/Initiate normal cell function
  • Steroids move right into cell w/o help

5

What is Affinity

Strength of binding b/t drug and receptor

6

Dissociation Constant (Kp)

Measure of a drug's affinity for a given receptor. 

The concentration of a drug needed for 50% receptor occupancy

7

What is an Agonist

Drugs that alter physiology of a cell by binding to plasma membrane or intracellular receptors

8

What is a Strong Agonist

Agonist that causes max effects even though it only occupy a small fraction of receptors

9

What are Weak Agonists

Agonists that need to be bound to many more recptors than a strong agonist does to produce same effect

10

Partial Agonist

Drug that fails to produce max effect even when all receptors are occupied

11

What is an Inverse Agonist

Binds to receptor and causes opposite of an agonist. Doesnt block anything from happening, it just reverses what happens

EX: H2 receptor antagonist

12

What is an Antagonist?

Inhibit/Block actions caused by agonists

13

Competetive Antagonist

Competes with Agonist for Receptors

  • Agonist cant bind to receptor while its occupied by antagonist
  • Antagonism can be overcome by high doses of agonists
  • EX: Reversal agents

14

Noncompetitive Antagonist

Binds to site other than the agonist-binding domain.

  • Induces form change in receptor so that agonist no longer recognizes agonist binding domain
  • Insurmountable - high doses cant defeat this antagonism
  • EX: Warfarin

15

Irreversible Antagonism

Agents compete with agonists for the agonist-binding receptor

  • Antagonists bind permanently to receptor
  • Rate of antagonism can be slowed by high # of antagonist

16

Efficacy

Degree that drug is able to cause max effects

17

Potency

Amount of drug needed to produce 50% of max effect that its capable of causing

18

Potency vs. Efficacy

  • Potency used to compare drugs in same class. 
    • Drugs in same class usually have same max efficacy
       
  • Efficacy used to compare drugs with different mechanisms. 

19

Drug-Response Curves

  • Graphs magnitude of drug action against concentration/dose of drug needed to induce action
  • Represents effects and dose of drug within individual rather than population
  • Almost all meds plateau at some point

20

What must be tested on a drug before they are approved for marketing?

Efficacy and Safety must be tested in animal and human population studies

21

What kind of data is derived from testing a drug's efficacy and safety?

EC50: Effective Concentration 50%

LD50: Lethal Dose 50%

Therapeutic Index

Margin of Safety

22

What is Effective Concentration 50%

Effective concentration of drug in 50% of test subjects

23

What is Lethal Dose 50%

Drug concentration that induces death in 50% of subjects

24

What is Therapeutic Index

Measure of safety of drug

LD50/ED50

25

What is Margin of Safety

Margin between therapeutic and lethal dose

26

Pregnancy Category A

Adequate and Well-Controlled studies have failed to show risk to fetus in first trimester and later trimesters.

27

Pregnancy Category B

Animal studies failed to show risk to fetus and no studies in pregnant women

28

Pregnancy Category C

Animal studies show adverse effects on fetus and no studies on humans. 

BUT

Potential benefits may warrant use on preggos despite potential risks

29

Pregnancy Category D

Positive proof human fetal risk, but potential benefits may warrant use of drug on preggos despite potential risks. 

30

Pregnancy Category X

Animal and Human studies show fetal abmormalities and the risks clearly outweigh potential benefits

EX: Warfarin, ACE Inhibitors