L3: Concentration Response Relationship Flashcards
• Draw typical “concentration vs response” and “log concentration vs response” curves with appropriately labelled axes • List some common responses to drugs and explain how they are measured • Distinguish between in vitro, in vivo and ex vivo measurements • Explain the term “EC50” and how it is measured • Distinguish between the terms “potency”, “potency ratio” and “relative potency” Explain the term “Therapeutic Index” and how it is measured
What does the concentration-response curve describe?
The relationship between drug concentration & response produced by the drug
What are the 3 main types of pharmalcological experiments?
In vivo
In vitro
Ex vivo
What is in vivo?
Inside of an living organism
What is in vitro?
Outside of an living organism
What is ex vivo?
Outside of an living organism, where cells, organs & tissues are removed, but then returned
How are drug effects studied in experiments in vitro?
Studied on a piece of tissue dissected from an animal & kept alive outside the body
How are drug effects studied in experiments in vivo?
Studied in the living animals e.g clinical trials
How are experiments in ex vivo ?
Animals are treated with the drug but then killed after a period of time
What concentration does most drugs act at?
1 x 10⁻⁶ to 1 x 10 ⁻¹²
What does a organ bath contain to keep tissue alive?
Physiological salt solution
What is the role of the force transducer?
Detect changes in tension by muscle
What is on the x and y axis of the concentration response curve?
X-axis: Representing the drug concentrations
Y-axis: Response (increase in force)
What does cumulative mean?
Increase in quantity by successive additions
Define potency
The concentration at which a drug is effective
How are doses expressed as?
Weight of drug per weight of animal
Define Emax
Max response the drug can produce
Define EC₅₀
Concentration of the drug that produces 50% of the max response
What does EC₅₀ represent?
Represents the potency of the drug
Where is the EC₅₀ found on the graph?
X-axis
If the EC₅₀ was lower, what does it mean for the potency of the drug
More potent
Define relative potency
Amount of a compound required to produce an effect when compared to another compound
Define potency ratio
Measure of the relative potency of 2 drugs
What is the therapeutic index?
Ratio between the toxic dose of a drug & the dose producing the desired therapeutic effect
What is LD₅₀?
Lethal dose in 50% of population
What is ED₅₀?
Effective dose in 50% of the population
Is Therapeutic index = LD₅₀/ED₅₀ used ?
Not anymore
Bigger the therapeutic index=
Safer the drug
