Agonists And Antagonists Flashcards
What is a agonist?
Thet are molecules capable of inducing a physiological response when binding to a receptor.
Agonists are classified according to their _________ and their __________.
Potency and efficacy
Full agonists do what?
Elicit a full response equivalent to the endogenous agonist. (100% response)
Partial agonist do what
elicit partial response (<100%)
What do inverse agonists do?
have intrinsic activity but elicit a response opposite response to that of an agonist.
What is a dose response curve?
is typically a plot of log[dose] vs the biological response.
The magnitude of the maximum response is termed the ________ and the ED50 is termed the __________.
efficacy, potency
Agonists are identified by?
exposing a cell or tissue to the drug then measuring a response.
Agonist conc. Is plotted on the ________ of a dose/response curve with the magnitude of the measured response plotted on the _______
X axis and y axis
administration of an antagonist by itself will elicit __________
No response
Antagonists act by?
altering the effect of a co-administered or endogneous agonist
Antagonists inhibit the response produced by an agonist.
TRUE OR FALSE
TRUE
To assay for antagonist potency, typically the ________ concentration is held constant and the _________ concentration is slowly increased to inhibit the stimulating effect of the agonist
Agonist, antagonist
To analyze this data, the concentration of the antagonist is plotted on the x-axis and the fractional response remaining is plotted on the y - axis. This creates an ?
Inhibition curve
IN A INHIBITION CURVE. Instead of an ED50, an IC50, or the concentration required to inhibit the agonist response, is measured as an indication of antagonist potency
TRUE
A competitive antagonist does what?
blocks activity of an agonist by binding to the same exact site as the agonist.
A non- competitive antagonist does what?
binds to a binding site other than the one that binds the agonist.
Typically a _________________________ will produce an apparent decrease in the Emax (maximum elicited response or the asymptote of the dose /response curve
Competitive antagonist
Agonists produce an effect when binding to a receptor by stimulating a ______________________?
signal transduction pathway
The signal transduction pathway includes conformational changes in the receptor that then produce secondary effects such as______________?
binding of other proteins, activation of enzymes, ion channel conductance and self modification (for example autophosphorylation) among many others
The range of ultimate effects is dictated by the?
receptor activated, the metabolism of the cell stimulated, competing signals from other receptors and the number and subtype of the many receptors in the cell.
__________ typically replicate the action of the endogenous agonist while _______________ typically block these effects.
Agonists and antagonists
Intrinsic activity
Intrinsic activity is the ability of a drug to induce an effect. It is an inherent ability based on the result of a drug binding to a receptor. If the drug can activate the receptor, it is said to have “intrinsic activity”. A drug with intrinsic activity is generally termed an agonist, while a drug that binds to a receptor with no intrinsic activity is called an antagonist.
Intrinsic efficacy
While the ability of a drug to elicit a response at a receptor is called “intrinsic activity”, the ability of a drug to elicit a specific amplitude of a response is called “intrinsic efficacy”. The efficacy of a drug is the magnitude of the response it produces; hence, intrinsic efficacy is the ability of a specific receptor/drug interaction to elicit a specific magnitude of response. A drug that elicits the maximum possible response is called a full agonist, while a drug that elicits a smaller response is known as a partial agonist.
Structure activity relationship
The relationship between the structure of the drug and its ability to produce a physiological effect.
