Principles of Pharmacodynamics Flashcards
(20 cards)
What are the two major theories of receptor binding and physiological action?
Occupancy
Rate
What is the rate theory?
The strength of the physiological response is directly proportional to the total number of encounters of the drug with its receptors per unit time
What is the occupancy theory?
The more receptors occupied the stronger the physiological response (50% occupied = 50% total strength)
How do spare receptors work?
Only a certain percentage of them have to be occupied for 100% physiological response
What are spare receptors?
Extra receptors on a cell surface that are not used
What is potency (receptor-affinity)?
The amount of a drug needed for an effect
What is efficacy (intrinsic activity)?
The amount of a response
What is a partial agonist/competitive agonist?
A drug that binds to a receptor but only gives partial efficacy compared to the full agonist
What is a allosteric agonist?
A partial agonist that binds to an allosteric site
What is a quantal dose-response?
The dose of a drug needed for it to have it’s effect
What is a quantitative response?
The number of people that respond to a given dose
What is a competitive antagonist?
Binds and blocks the active site of the receptor; typically larger with higher affinity and lipid soluble
What is a pharmacologic antagonist?
An antagonist that binds the same receptor
What is a physiologic antagonist?
An antagonist that blocks the action of a drug downstream not directly at the receptor
What is the formula for margin of safety?
LD01/ED99
What is the formula for therapeutic index?
LD50/ED50
What is an inverse agonist?
Binds to receptor or allosteric site and turns a physiological response off that is usually always on
What is an additive interaction?
The interaction of two different drugs add their effects together 1+1=2
What is a potentiation interaction?
The interaction of two different drugs one that does not have an effect on its own but increases the effect of the drug it is combined with 1+0=2
What is a synergism interaction?
Two drugs are agonist increasing each others affects 1+1=3
