03: Dose Response Relationship 3 Flashcards
In a graded drug response, how does dose relate to effect?
Dose is related to the INTENSITY of the effect
In a quantal drug response, how does the dose relate to the effect?
Dose is related to the FREQUENCY of the effect
How is a drug’s quantal effect studied? (Single Biological Unit/Population Studies)
Population Studies
Is a graded drug response measured on a continuous scale or in an “all or none” pharmacological effect?
Continuous Scale
What does the term Potency mean in respect to drugs?
The amount of drug needed to produce a given effect
What quality of the drug molecule has the largest influence on its potency?
Its affinity for the target receptor
Is potency of great concern to clinicians?
Not really because the potency can be controlled through the dosage
How is potency expressed?
EC50 (uM)
ED50 (mg/kg)
This term describes the maximal effect that can be produced by a drug
Efficacy
Which molecules have the lower maximal effect? Partial Agonists or Full Agonists?
Partial agonists
What property of the drug has the largest influence on its efficacy?
The receptor-effector system
What is more important clinically, the drugs potency or its efficacy?
Efficacy
What is the difference between a Full Agonist and a Partial Agonist in terms of their ability to induce a conformational change in their target receptors?
A partial agonist can only induce some degree of receptor activation; but not enough to induce a maximal response
The full agonist leads to a conformational change that results in full activation of the receptor response
What does the shape of the D-R curve describe?
The drug binding to its receptors
What does the steepness of the curve indicate?
The useful dosage range
What aspect of the drug is the slope of the curve related to?
The toxicity
Are D-R curves with steep slopes more or less toxic?
More, because you get to the max with a smaller dose
Change in efficacy with or without changing the ED50
Non-competitive Antagonist
Change in ED50 without a change in Efficacy
Competitive Antagonist
How are toxicity of drugs compared?
By their ED50
The question, how many people got sick out of a group of 100 taking a drug? Would be an example of…..(Quantal/Graded)
Quantal
When can partial agonists be useful?
When you don’t want to induce a maximal effect
Agonist that locks a receptor in an inactive state but produces the opposite of the “real” agonist’s effect.
Inverse Agonist
Are antagonists and inverse agonists the same thing?
No. Antagonists just lock up the receptor, they do not produce an effect
What will the antagonist “block” from the receptor besides the agonist
Inverse agonists for that receptor as well
What is the difference between a competitive antagonist and a non competitive antagonist
Competitive agonists bind in the same site on the receptor
How can the effect of an antagonist be overcome?
Increasing the concentration of the agonist
What produces a shift to the right (delta ED50/affinity/potency) without changing the Emax/Efficacy
Competitive antagonists
With the introduction of a competitive antagonist, does the absolute affinity of the receptor change?
No, but you need to increase the dose of the agonist in order to get the same response; and therefore the relative affinity has been shifted to the right
What will depress the Emax and shift the entire curve to the right?
Non-competitive antagonist
The effect of what type of antagonist could be considered “taking receptors out of the pool”
Non-competitive antagonists
