Pharmacodynamics Flashcards
Effect of the drug on the body
Pharmacodynamics
Effect of the body on the drug
Pharmacokinetics
What is a Dose-Response Curve?
Relationship between a drug and its effects
If the Dose-Response curve is plotted arithmetically, what shape will it be?
Hyperbolic
More commonly, if the Dose-Response curve is plotted with the LOG of drug dose, what shape will it be?
Sigmoidal
What is Emax and where is it found?
Maximal effect produced by a drug
- Top of Y axis (100% response)
What is ED50 and where is it found?
Drug dose that produces 50% of maximal effect
- X axis that coordinates to 50% on Y axis
Graded Dose-Response curves represent?
MEAN VALUE within a population/person
With Graded Dose-Response curves, the magnitude of response varies ______
Continuously
Quantal Dose-Response curves examine?
FREQUENCY of a response within a population
What are the 2 types of Quantal Dose-Response curves?
Non-cumulative
Cumulative
Non-cumulative Quantal Dose-Response curves measure?
% of people responding at a dose and ONLY AT THAT DOSE
Cumulative Quantal Dose-Response curves measure?
% of people responding at a dose AND AT ALL DOSES LOWER than that dose
What shape is the Non-cumulative Quantal Dose-response curve?
Bell shaped
What shape is the Cumulative Quantal Dose-response curve?
Sigmoidal
Median Effective Dose
ED50
Median Toxic Dose
TD50
Median Lethal Dose
LD50
Therapeutic Index (TI) =
TD50/ED50
The greater the Therapeutic Index (TI) the?
Safer the drug
Drug Potency
Amount of a drug required to produce a specific effect
Drug Potency is represented by?
ED50
The lower the ED50 on the x axis, the more ___ a drug
Potent
Drug Efficacy
Maximal effect produced by a drug
Drug Efficacy is represented by?
Emax
The higher the Emax on the Y axis, the more ____ a drug
Efficacious
Drug efficacy is related to the _____ available to bind the drug
of receptors available to bind the drug
What determines the drug dose used clinically?
Drug potency
What determines the magnitude of the clinical effect?
Drug Efficacy
What are 4 parameters to describe the interaction of a drug with its receptor?
Binding
Affinity
Selectivity
Intrinsic Activity
What type of bonds to most drugs use to bind to their receptors?
Reversible Non-covalent bonds
How readily and tightly a drug binds to its receptor
Affinity
A HIGH affinity correlates to _____ drug needed for a response
LESS
A LOW affinity correlates to ____ drug needed for a response
MORE
KD
Drug concentration at which 50% of binding sites are occupied by the drug
KD is on the ___ axis
x axis
A LOWER KD =
HIGHER AFFINITY
Property of a drug determined by its affinities at various binding sites
Selectivity
KD ratio measures?
Selectivity
KD ratio
KD off-target / KD target
The HIGHER the KD ratio, the _____ the selectivity
HIGHER Selectivity
The HIGHER the selectivity, the ____ adverse effects
LOWER adverse effects
What is Intrinsic Activity?
Ability of a drug to change receptor function and produce a physiologic response
Ability of a drug to change receptor function and produce a physiologic reponse
Intrinsic Activity
Bind receptor, stabilizes it, and produces a physiologic reponse
Agonists
Do Agonists have intrinsic activity?
YES
Bind receptor, and do NOT change its function
Antagonists
Do Antagonists have intrinsic activity?
NO - do not change receptor function or produce physiologic response
3 types of Agonists?
Full Agonist
Partial Agonist
Inverse Agonist
What type of agonist mimics actions of endogenous chemicals?
Full agonists
What type of agonist produces opposite effects of the other agonists and decreases receptor signaling/response?
Inverse agonist
What agonists/antagonists block action of endogenous chemicals?
Partial and Inverse agonists
All Antagonists
3 broad categories of antagonists?
Pharmacologic
Chemical
Physiological
2 types of pharmacologic antagonists?
Competitive
Non-competitive
2 types of Non-competitive pharmacologic antagonists?
Irreversible
Allosteric
Pharmacologic antagonists act where?
Same receptor as agonists/endogenous chemicals
Chemical antagonists make drugs?
Unavailable
Competitive antagonists compete for binding at the receptor. Can they be displaced and overcome?
YES
With Competitive Antagonists present, describe Emax and EC50 for an Agonist
Emax = unchanged EC50 = increased
Can Non-competitive antagonists’ receptor inactivation be overcome?
NO
How do Irreversible Antagonists work?
Occlude Agonist site using covalent bonds (irreversible)
How do Allosteric Antagonists work?
Bind to site OTHER THAN agonist site
= Decreases agonist binding or receptor activation
With Non-competitive Antagonists present, describe Emax and EC50 for an Agonist
Emax = decreased EC50 = unchanged