Pharmacodynamics Flashcards
Effect of medications on the body
Pharmacodynamics
How strong a medication binds to its receptor
Affinity
An increase in AFFINITY leads to
an increase in POTENCY
The amount of medication to elicit an effect
Potency
An increase in affinity leads to an increase in potency which also leads to
An decrease in the dose
Maximal effect of the drug
Efficacy (Emax)
The smaller the EC50
The higher the potency
If two drugs have the same Emax they also have the same
Efficacy
Two drugs with the same Emax but the one with the low EC50 is
More potent
All available receptors bound to an agonist
Full agonist
Lower intrinsic activity (lower emax)
Partial agonist
An antagonist which is reversible and can be overcome with an increase in Ligands
Competitive antagonist
An antagonist that binds to an allosteric site changing shape of the receptor
Non competitive antagonists
What does a full antagonist do to a full agonist
Influences the dose needed to elicit a maximal response but doesn’t effect the extent of the maximal response
Full agonist with a non competitive antagonist
Drops the emax
When a maximal response of a drug seen without binding to all the receptors
Presence of spare receptors
Up regulation of receptors occurs when ?
Receptor activation is lower than normal
Ability of a cell to produce a response will drop RAPIDLY, can occur with initial dose.
Desensitisation
Ability of a cell to produce a response will drop after continued stimulation gradually
Tolerance
dose of a drug observed to yield half-maximal efficacy.
ED50
dose of a drug observed to yield half-maximal toxicity.
TD50
is a quantitative measurement of the relative safety of a drug.
Therapeutic index
TD50/ED50
Therapeutic index
Low TI
Bad
High TI
GOOD
what is the difference between an agonist and an inverse agonist
an inverse agonist is a drug that binds to the same receptor as an agonist but induces a pharmacological response opposite to that of the agonist. … An agonist increases the activity of a receptor above its basal level, whereas an inverse agonist decreases the activity below the basal level.
