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Pharmacodynamics
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32
Pharmacology
Graduate
08/14/2012

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Term
What is the definition of pharmacodynamics?
Definition
The study of the biochemical and physiological effects of drugs and their mechanisms of action
Term
What physical characteristics of drug molecules determine binding specificity?
Definition
Drug size, shape, stero-isomerism (only one optical isomer), and polarity
Term
What pulls ligands closer to the receptor? What couples the ligand to the receptor?
Definition
Ionic bonds bring the ligand close to the receptor, hydrogen or van der waals forces couple the ligand to the receptor
Term
What is binding affinity (Kd)
Definition
A measurement of how readily a molecule will bind to a receptor, also the concentration of drug required to bin 1/2 of the receptors in a fixed population (high Kd means low affinity)
Term
What is the law of mass action?
Definition
L + R <-> LR* -> biological response
(L = ligand, R = receptor)
Term
How does Le Chatelier's theory apply to receptor theory?
Definition
A change in the concentration of the drug or the receptor will shift the biological response one way or another
Term
What is affinity?
Definition
The strength of the attraction between a ligand and a receptor
Term
How do you calculate the equilibrium disassociation constant (Kd) of affinity?
Definition
Kd = [L][R]/[LR], you can find it on a graph by looking at the concentration of the drug required to occupy 50% of the receptors
Term
What is efficacy in receptor theory?
Definition
A characteristic property of a ligand to induce the receptor to adopt an active conformation to generate a biological response (varies between 0-1)
Term
What is an agonist?
Definition
A substance which binds to a receptor and produces a biological response
Term
What is a full agonist?
Definition
Substance capable of generating the maximum biological response a system can achieve by activating 100% or less of the receptors, affinity and efficacy = 1
Term
What is a partial agonist?
Definition
Substance that produces, even at its highest concentration and 100% receptor occupation, less than the maximum response achievable by a system, affinity is and efficacy are between 0-1
Term
What is an inverse agonist?
Definition
A substance that produces a decrease int he basal activity of a system
Term
What are allosteric agonists or enhancers?
Definition
Chemical compounds that increase the affinity and/or efficacy of agonists for receptors by binding and altering receptor conformation
Term
What are the different types of antagonists?
Definition
Chemical and physiologica
Term
What is indirect antagonism?
Definition
A substance that inhibits a biological response by acting at a site beyond the receptor, can antagonize agonists acting through more than one receptor
Term
What are competitive antagonists?
Definition
Most common, endogenous agonists and exogenous antagonists compete for a binding site on the receptor, has affinity but no efficacy
Term
What characterizes equilibrium competitive antagonists?
Definition
Reversible, antagonism increases at increased concentrations, can be overcome by increasing the amount of agonists
Term
What characterizes nonequilibrium competitive antagonists?
Definition
Binds irreversibly to receptor via covalent bond, antagonism increases with concentration, cannot be overcome by increasing agonist amount
Term
What distinguishes allosteric agonists?
Definition
Reduces affinity or efficacy of agonists by binding receptors on sites distinct from the agonist binding site
Term
What is a dose-response curve?
Definition
Graphical representations of the relationship of the quantity of a substance (drug or ligand) to the graded effect that the substance has on a biological system
Term
What is a graded response?
Definition
A response is one that changes proportionately with each single dose of drug given with each dose producing a single tissue response
Term
What do quantal dose-response curves represent?
Definition
The "all or nothing" theraputic endpoints of a drug based on dosage
Term
What is potency?
Definition
A comparison of the relative effectiveness of drugs acting by similar mechanisms by comparing ED50 values
Term
Intrinsic activity is another name for what?
Definition
Efficacy
Term
How is equilibrium competitive antagonism graphically represented?
Definition
Rightward shift (apparent decrease in potency) of the dose-response curve while still being able to achieve a maximum response (albeit at a much higher dose of agonist)
Term
How is nonequilibrium competitive antagonism graphically represented?
Definition
Downward shift, maximum response is impossible to attain regardless of dose
Term
What is indirect antagonism?
Definition
Antagonist that inhibits the generation of a biological response by acting at some point down stream of the receptor (i.e. with components of its signal transduction cascade), can be reversible or irreversible
Term
What receptors are adrenergic receptors?
Definition
Alpha and Beta receptors
Term
What receptors are serotonergic receptors?
Definition
5-HT receptors
Term
What receptors are muscarinic cholinergic (Ach) receptors?
Definition
M1, M2, M3, M4, M5 receptors
Term
What receptors are histamine receptors?
Definition
H1 and H2 receptors
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