lecture2 Flashcards
1
Q
Define Agonist
A
- drug or ligand that binds to a receptor and produces a MOLECULAR, CELLULAR or PHYSIOLOGICAL response
2
Q
define antagonist
A
- a drug or ligand that binds to a receptor and INHIBITS the RESPONSE produced by an agonist
3
Q
define competitive antagonist
A
- Agonist and antagonist compete for the SAME binding site
- causes a shift to the right in the EC50; but maximal effect is still achievable
4
Q
define noncompetitive antagonist
A
- Agonist and antagonist bind to DIFFERENT sites
- decrease in maximal effect; agonist affinity for the receptor may not change in presence of noncompetitive antagonist
5
Q
define partial agonist
A
- Drug that produces a lower maximal response as compared to the agonist
–> as binding of partial agonist to the receptor INCREASES, the binding of the agonist DECREASES
–> the response of a partial agonist is less than the agonist
–> the net response to apartial agonist in the presence of an agonist is a reduction in physiological effect
6
Q
define ED50
A
dose at which 50% of people exhibit a specific quantal effect
7
Q
define TD50
A
- dose at which a specific toxic effect occurs in 50% of the individuals tested
8
Q
define LD50
A
- dose that is lethal for 50% of individuals tested
- experimentally defined with animal models
9
Q
describe therapeutic index
A
- indicator of safety
- the greater the ratio or the greater the windown between TD50 and the ED50 = the safer the drug is for patients
- TI = TD50/ED50
10
Q
Define Tolerance
A
- decreases in drug response following repeated administration of the drug (SHIFT TO THE RIGHT)
- causes for tolerance that include changes in pharmacokinetic parameters, changes in pharmacodynamic paramters or behavioral changes
11
Q
define sensitization
A
- increase in drug resposne following repeated exposure to a drug
- represents a shift to the left
