Quiz 13 Flashcards
Define pharmacokinetics
The actions of the body on the drug
Define pharmacodynamics
The actions of the drug on the body
Usually this means ‘how does the drug bind to the receptor’
Name four examples of pharmacokinetics
ADME
Absorption
Distribution
Metabolism
Elimination
Define what an agonist is
Drug or natural ligand that activates the receptor. Sometimes selective, sometimes not
What does the dose response curve look like for an agonist?
Sigmoidal
Define what an antagonist is
Binds to the receptor in the same location as the agonist would. However it does not activate a response. Thus it interferes with the agonist.
What happens to the dose response curve when you add an antagonist
It shifts the dose-response curve to the right. Slope and shape of the sigmoidal curve remains the same
If you have antagonist in solution, how do you overcome this to get a desired effect?
Increase the concentration of agonist
Define what an allosteric activator is
It binds to the receptor at a separate location from where the agonist binds and potentiates the effect.
(It changes the configuration of the receptor to better receive the agonist)
Describe the changes to the dose-response curve when an allosteric activator is added
The plateau (think Vmax) is raised. This means that the same concentration of agonist brings about a greater effect.
Describe what an allosteric inhibitor is
It binds to the receptor at a location separate from the agonist site, thus it is noncompetitive. Actions are often reversible.
Describe the dose-response curve change that occurs when an allosteric inhibitor is added
The plateau (think Vmax) is lowered. Meaning the same concentration of agonist is less effective at bringing about a response
True or false… receptors may be active, producing an effect, even in the absence of drug
True. Very small amounts however. “In the absence of drugs, the two isoforms of receptors are in equilibrium and Ri is favored”
True or false.. If a receptor is bound to drug, it must be in the active form
False. “Inactive receptors can exist, even if paired with MOST drugs”
Receptors are in equilibrium between the inactive and active forms. Without drug the ____ form is favored. With drug the ____ form is favored.
1) inactive
2) active
Define full agonist. Describe its dose-response curve
This agonist has a much higher affinity for the active receptor, thus the equilibrium favors the Ra-D form the most, resulting in the largest effect.
The curve has the highest plateau
Describe what a partial agonist is. Describe what the dose-response curve looks like
A partial agonist produces a lower response than full agonists because the agonist has intermediate affinity for both Ri and Ra. (Meaning the equilibrium is shifted more towards the Ri side, resulting in less of a response). The Ra-D complex is less stable.
This simply lowers the plateau on the curve
Describe what an inverse agonist is. What doe its dose-response curve look like?
this agonist has a greater affinity for Ri, thus equilibrium favors the Ri-D complex (very stable), resulting in a decrease of activity compared to the constitutive activity. Thus, inverse agonists can produce contrasting physiologic results.
The plateau shifts down, even below the constitutive activity
Describe what a conventional antagonist is and what its dose-response curve looks like
A conventional antagonist has equal affinity for the Ra and Ri, thus has NO CHANGE in constitutive activity.
The dose-response curve is flat, at the same level as constitutive activity.
What is EC50?
The concentration of agonist at which you get 50% of the effect
What is Kd?
The concentration of agonist in which half of the receptors are bound.
What is IC50?
This is the concentration of the ANTAGONIST in which you have 50% of the effect
True or false. EC50 = Kd
FfAaLlSsEe
What happens to EC50 when you add competitive antagonist to the solution?
The EC50 shifts to the right (think Km)