Lecture 18 - Review Of Pharmacodynamics Flashcards
What is 0.0001 in exponential/scientific notation?
1x10^-4
What is 10^3 in log notation?
Log(base 10)1000 = 3
What is a ligand?
A substance that can interact with a target protein or receptor
What is an agonist?
A ligand that can interact/bind to a target protein, activating stimulating a biological response
What is an antagonist?
Ligands that have a affinity for a receptor or target protein that dont produce a biological response
Antagonists block the action of agonists
What is affinty?
A measure of strength of the interaction between a ligand/drug binds to a receptor
What measurement is used to define affinty?
Kd
What is Kd?
The concentration of ligament at which 50%of all available receptors are bound
What does a high value of Kd mean?
What does a low value of Kd mean?
High Kd = low affinity of drug (high conc of drug needed to occupy 50% of receptors)
Low Kd = high affinity of drug (low conc of drug needed to occupy 50% of receptors)
What is intrinsic efficacy?
The ability of a ligand to generate the active form of the receptor
What is the notation for the active form of a receptor?
R*
What is ligand efficacy?
The ability of a ligand to cause a measurable biological response
Comprises ligand efficacy and tissues ability to produce response
What is potency?
Essentially how good a drug is at evoking a response
The concentration of a drug that evokes 50% of its maximal response (Emax = EC50)
What does a low EC50 mean?
What does a high EC50 mean?
Low = More potent (less drug required to generate 50% of max response)
High = Less potent (more drug required to generate 50% of max response)
What is Emax?
The concentration of drug needed to reach the maximum response
What is Bmax?
Concentrations of drug required to reach maximum receptors bound
What is a partial agonist?
Ligands that evoke responses that are always lower than the maximum response of a full agonist
How does a full agonists Intrinsic activity compartment to a partial agonists?
Partial agonist = lower intrinsic activity
Full agonist = higher intrinsic activity
What is the difference between an agonists intrinsic efficacy and an antagonists intrinsic efficacy?
Antagonists = no intrinsic efficacy but affinty
Agonist = intrinsic efficacy and affinity
How would a drug with a high intrinsic efficacy Emax compare to a drug with low intrinsic activity?
High intrinsic activity = higher Emax
The larger the max point on a response curve the higher the intrinsic activity
On a response/conc graph how can you determine which drug has the highest potency?
The drug furthest to the left which reaches its EC50 the quickest
On a response/conc curve how can you estimate the affinity of a partial agonist?
For a partial agonist EC50 and its affinity are very similar
What values can be determined from a Porportions of receptor bound - Conc graph for a drug?
Kd (affinity)
Bmax (max binding capacity)
What values can be determined from a Response - Conc graph for a drug?
EC50 (potency)
Emax (intrinsic activity)
What values will be different if there are spare receptors?
How will these values differ?
Kd
EC50
When EC50 is less/smaller than Kd
What is Functional antagonism?
Antagonism of a cellular/tissue event being mediated by one mechanism by another mechanism
What are the 3 types of drug antagonism?
Reversible competitive antagonism
Irreversible competitive antagonism
Non competitive anatongism
What is reversible competitive anatagonism?
Same binding site (orthosteric site) as endogenous ligand
Interaction is a relatively weak bond (associates and dissociates)
What is irreversible competitive antagonism?
Same binding site (orthosteric site) as endogenous ligand
Interaction is very strong (often covalent) antagonist dissociates very slowly or never
What is non competitive antagonism?
Antagonist binds at a site away from the orthosteric site known as the Allosteric site
