Define the term pharmacodynamics and distinguish pharmacodynamics from pharmacokinetics
- Pharmacodynamics: effects of drugs on the body (drug receptors, dose-response curves, and MODA)
- Pharmacokinetics: effects of the body on drugs (absorption, distribution, metabolism, elimination)
A specific molecule in a biological system that plays a regulatory role defines what?
What kind of curve is typically seen when you plot a drug dose arithmetically?
What kind of curve do you get when you plot a concentration-effect curve (logarithm of drug vs. response)
What type of response answers the question: "How much?"
This response typically represents which value within a population or a single subject?
- Mean value
What type of response is used to examine the frequency of (i.e., number of individuals showing) a response within a large population?
What is a Non-cumulative vs. Cumulative quantal dose response curve?
- Non-cumulative: number or % of individuals responding at a dose of a drug and only at that dose
- Cumulative: number or % of individuals responding at a dose of a drug and at ALL doses LOWER than that dose
How to calculate therapeutic index (TI)?
What does a higher TI indivate in regards to drug safety?
TI = TD50 / ED50
*Higher the TI the safer the drug
The range of doses of a drug or of its concentration on a bodily system that provides for the safe and effective therapy, defines what?
The ability of a drug to change a receptor function and produce a physiological response upon its binding to a receptor, defines what?
Define physiologic antagonism
Occurs between endogenous pathways regulated by different receptors
A pharmacologic antagonist that binds agonist binding site and is reversible is considered what type of antagonist?
Competitive; can be displaced from receptor by other drugs
A pharmacologic antagonist that binds the agonist binding site and is irreversible is considered what type of antagonist?
Noncompetitive agonist site antagonist
List the non-covalent bonds from stongest to weakest.
Ionic > Hydrogen > Hydrophobic > Van der Waals forces
How readily and tightly that a drug binds to its receptor describes its what?
A property of a drug determined by its affinities at various binding sites describes what?
(T or F) Antagonists have intrinsic activity?
Cholestryramine is a bile acid-binding resin that is used for the Tx of hypercholesterolemia. It absorbs aspirin, preventing its absorption in GI tract and antagonizing its effects.
Cholestyramine is an example of what type of antagonist?
*Chemical antagonism: when chemical antagonist makes the other drug unavailable
Describe a covalent bond drug receptor interaction
Irreversible; drug removal requires new synthesis of a recptor or enzymatic removal of the drug
How do you plot a dose response curve? (i.e., what's on each axis)
Dose on x axis and drug effect on y axis (hyperbolic curve)
What is ED50?
Effective dose: dose of drug that produces 50% of its maximal effect
What does a qunatal response require?
Pre-defined response (i.e., death, falling asleep, 10% reduction in BP)
What is the parameter that describes affinity?
- Kd = drug concentration at which 50% of the drug receptor binding sites are occupied by the drug; unit used is molar
- Lower Kd = higher affinity
What is a full agonist?
- Fully activate receptors
- Produce maximal pharm effect when all receptors occupied
- Maximal intrinsic activity
What is an inverse agonist?
- Decrease receptor signaling
- Decrease response at receptors w/ significant level of constitutive receptor activity
- Intrinsic activity is present and related to the inhibition of receptor function
*Inverse agonist would bind and cause low BP, while an antagonist would prevent the agonist from binding, thus preventing high BP
What is chemical antagonism?
When the chemical antagonist makes other drug unavailable
Describe what competitive antagonism does to the dose response curve?
Increases EC50, but does NOT change Emax
Describe what non-competitive antagonism does to the dose response curve?
Decreases Emax but does NOT change EC50
What is drug efficacy and how is it represented?
What happens when the value representing it increases?
- Maximal pharmacological effect that a drug can produce; represented by Emax
- Greater the Emax, the more efficacious the drug
- Efficacy is related to the total number of receptors available to bind a drug
- Determines clinical effectiveness
What is drug potency and how is it represented?
- Amount of drug required to produce a specific pharm effect
- Represented by the ED50
- The lower the ED50, the more potent the drug