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A drug may increase of decrease cell function, but does NOT:

initiate new cellular function


Important attributes of receptor-mediated processes:

-Self-limiting on short time scales
-Organized in opposing systems
-Small signals can be amplified
-Large number of receptors operate through a small number of 2nd messenger systems


Occupancy theory assumes that:

The response or effect, is proportional to the receptor occupancy.

And that each receptor only binds to one ligand!


Explain affinity:

Ability to form complex with receptor. Greater affinity will lower the amount of drug required to produce effect.

The curve looks the same, but will shift toward the right with lower affinity


What does potency mean with regard to the dose-response curve?

Potency is the relative position of the curve. Further to the left means that the drug is more potent


Explain efficacy:

Capacity to produce the response
Full efficacy is alpha=1


Difference between full and partial agonists?

Full agonist produces the maximal response and has full efficacy (alpha = 1)

Partial agonist produces a less-than maximal response. The alpha will be somewhere between 0 and 1.


Pure antagonist is defined how?

Has affinity for the receptor and stops agonist from binding. At the same time has NO efficacy. alpha=0


What will competitive and noncompetitive antagonists do to the dose response curve?

-Shifts dose-response to the right
-Slope stays same
-Adding more drug will help recover activity

-slope reduced
-Vmax reduced
-Adding more drug will not recover activity


Partial agonists are important why?

Turns out that in the presence of a full agonist, a partial agonist will e sort of an antiagonist, but not quite as bad because they still create an effect.


Inverse agonists do what?

They can actually lower the activation of a recptor to BELOW basal levels. WHOA!


Quantal dose effect:

Individuals can differ from the median effective dose of a drug. They can either be hyporeactive of hyperreactive


What does the therapeutic index measure?

The relative safety

Difference between ED(effective dose) and LD(Lethal Dose).

Usually you want this margin to be very large. In extreme cases it is small and must be managed very careful for very serious disease.


Imperfect selectivity of a drug to its particular receptor leads to what?

Drug side-effects.