Pharmacodynamics (Chapter 3) Flashcards
what is the difference between pharmacodynamics and pharmacokinetics ?
pharmacokinetics: how the body acts on the drug
pharmacodynamics: how the drug acts on the body
what is an agonist ?
a ligand that binds to a receptor and initiates a change in the cell via a transduction mechanism
what is an antagonist ? give an example.
a ligand that binds to a receptor but does not initiate a change in the cell- it has no function. It blocks the endogenous compound, like a “blocker”
beta-blocker
what is a site of action ?
specific molecular surface on the target, usually a receptor, where the drug binds
what is the onset of action ?
the time it takes for the concentration of a drug at the site of action to be large enough to cause a response.
what is the duration of action ?
time between onset and termination of action, the time the drug produces the effect.
what is receptor theory?
most drugs interact with a receptor- agonist brings a productive change to the target cell, antagonist brings an unproductive change to the target cell.
what are the three places where you can find receptors on a cell?
on cell surface
in cytoplasm
in nucleus
where do most protein-based drugs bind to receptors ?
on cell surface
where do most lipid-based drugs bind to receptors ?
cross the membrane
what kind of reaction does NE and E binding to an alpha-1 receptor bring ? by what pathway?
PIP2 cleavage by phospholipase C produces second messengers IP3–> produces Ca2+ –> smooth muscle contraction
and second messenger DAG
what kind of reaction does NE and E binding to an alpha-2 receptor bring ? by what pathway ?
inhibits the release of NE and E by negative feedback
inhibits adenylyl cyclase, provoking smooth muscle contraction
what kind of reaction does NE and E binding to a beta receptor bring ?
ATP goes to cAMP thanks to adenylyl cyclase
heart muscle contraction, smooth muscle relaxation, glycogenolysis
draw a graph which shows the plasma concentration of a drug over time
I . peak concentration.
I . .
I . .
I . .
I . . minimum effective concentration
I . .
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_
I duration of I
I action I
onset termination
half-life: in the middle of the duration of action
the curve that shows the plasma concentration of a drug over time- how would you explain to an athlete, using this graph, why they shouldn’t take too much pain medication ?
either you have pain or you don’t. there isn’t such a thing as “feeling less pain”. When the curve increases, you’re not “feeling less pain”, and taking more of a drug won’t increase the effect. An increased dose would be for an increased duration of action, not for a better treatment.
