TEST 2 Dose-Response Relationship Flashcards
Define dose:
The amount of drug administered
Define response?
A change in biological activity.
Define Dose-response relationships?
The relationship between the amount of a drug administered and the observed change in a biological function.
What are the two response theories?
Occupation and Rate Theory
Describe Occupation Theory?
The magnitude of a response is proportional to the number of receptors occupied by a drug.
Describe Rate theory?
The magnitude of a response is proportional to the rate of formation of the D-R complex.
Define the Dissociation constant mathematically.
KD=K2/K1
Define Intrinsic Activity?
The ability of a drug to induce a biological response.
Define Efficacy?
Maximal effect produced by a drug
Define Potency?
Determined by the dose needed to produce a particular effect of given intensity
Define Agonist?
A drug which possesses affinity and intrinsic activity.
Define Partial Agonist?
An agonist with lower efficacy than a full agonist
Define Antagonist?
A drug which possesses affinity but little or no intrinsic activity.
Define Specificity?
Ability of a drug to exert its effect through a single mechanism of action
Define Selectivity?
Ability of a drug to induce one effect in preference to another effect.
What type of graph does an Competitive antagonist create?
Logarithmic curve
What effect does a competitive antagonist have on the agonist effect graph.
Moves the curve to the left.
What type of graph does an Non-competitive antagonist create?
Logarithmic curves
What effect does a competitive antagonist have on the agonist effect graph?
Lowers peak % maximal effect
What effect on the agonist do different antagonists have on a double reciprocal plot.
- Non-competitive antagonist:
- x-intercept doesn’t change
- y-intercept moves up.
- Competitive antagonist
- x-intercept moves right.
- y-intercept doesn’t move.
Define Median Effective Dose (ED50)
Dose required to produce specific therapeutic effect in 50% of test subjects.
Define Lethal Dose (LD50)?
Dose required to produce death in 50% of test subjects.
Define Median Toxic Dose (TD50)?
Dose required to produce a toxic effect in 50% of test subjects.
Define Therapeutic ratio or index?
The LD50/ED50 ratio for a drug. The larger the ratio, the safer the drug.
Define Certain Safety Factor?
- The LD1/ED99 ratio for a drug.
- If the ratio is:
- <1, the two curves overlap
- >1, little or no overlap.
- If the ratio is:
Define Standard safety margin?
(LD1-ED99)/ED99 X 100 =
Represents the percent that the ED99 must be increased to be lethal in 1% of the test subjects.
What are the three decreased response relationships?
Tolerance, Tachyphylaxis, Resistance
What are the three increased response relationships?
Additive effects, synergism, potentiation.
Define Tolerance:
A decrease in efficacy with repeated drug administration.
Define Tachyphylaxis
An acute form of tolerance due to rapid, repeated administration of a drug.
Define Resistance:
A decreased or complete lack of responsiveness to drugs that normally inhibit or cause cell death.
Define Additive effects:
The combination of two drugs induces an effect equal to the sum of the effects of the two drugs when administered individually.
Define Synergism:
The combination of two drugs induces an effect which is greater than the sum of the effects of the two drugs when administered individually.
Define Potentiation:
Administration of a drug with little or no efficacy enhances the biological shift to the left of the dose-response curve for the antagonist.
