4: Pharmacodynamics Flashcards
Pharmacokinetics vs pharmacodynamics
Kinetics: effects of body on drugs
Dynamics: effects of drug on body
Emax vs ED50
Emax: max effect that can be produced by a drug
ED50: dose of drug that produces 50% of max effect
What does the graded dose response curve represent?
Mean value within a population or a single subject
What does a quantal dose response curve show
Does the response occur or not, and in how many people? Is a yes/no binary response
Two axes on a quantal dose response curve
X: drug dose
Y: % of individuals that respond to the drug at that dose
Non-cumulative vs cumulative quantal dose response curve
Non-cumulative: number of individuals responding to a drug only at that dose (bell shaped)
Cumulative: number of individuals responding to a drug at that doses and all doses lower (sigmoidal shaped)
How to interpret therapeutic index
Higher index = safer drug
Therapeutic window
Range of doses of a drug in a body that provides for the safe and effective therapy
Potency
Amount of drug required to produce a specific pharmacological effect
What does a low ED50 mean?
More potent drug
Efficacy
Max pharmacological effect a drug can produce
What does higher Emax mean?
More efficacious drug
Covalent vs non-covalent bonds in drug receptor binding
Covalent: irreversible
Non-covalent: reversible, most drugs use this
Three non-covalent bonds, from strongest to weakest
- Ionic bonds
- Hydrogen bonds
- Hydrophobic interactions
With high affinity, does one need more or less drug to produce a response?
Less drug needed
KD
Equilibrium dissociation constant - describes affinity of a drug
What does lower KD mean?
Higher affinity of a drug for a receptor
What happens to the KD ratio with a more selective drug?
Higher ratio (KD off target / KD target)
Do more or less selective drugs have more side effects
Less selective -> more side effects
Intrinsic activity
Ability of a drug to change a receptor function and produce a physiological response upon binding to receptor
Antagonists
Bind receptor but do not change its function, only prevent activation (dont have intrinsic activity)
When all receptors are full with partial agonists, what happens?
Sub-maximal pharmacological effect
Inverse agonists
Produce an effect opposite to an agonist
Three types of antagonism and describe them
- Pharmacologic: action at same receptor as endogenous ligand
- Chemical: chemical makes other drug unavailable
- Physiologic: occurs between endogenous pathways regulated by different receptors
