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21 terms

Competitive and Non-Competitive Antagonism

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antagonist
a drug that neutralizes or counteracts the effects of another drug
mutually exclusive
In competive antagonism, the binding or agonist and antagonist are...
reversible competitive antagonism
This type of antagonist can be reversed with an increase in concentration of agonist
atropine (mAChR blocker
example of an reversible competitive antagonist...
irreversible competitive antagonism
This type of antagonist cannot be reversed without a complete regeneration of the system. Binds at same site as aognist
phenoxybenzamine (a blocker)
example of irrevesible competitive antagonist...
[A]'/[A]
concentration ratio=
-log [B]r=2
The negative logarithm of [A] which causes a CR of 2 is equal to...
gaddum equation
Expresses how the proportion of agonist bound receptors is dependant on the concentration of A and B.
pAR=[A]/kA(1+[B]/kB)+[A]
The gaddum equation
CR
r=
r-1=[B]/kB
The schild equation
Schild equation
Equation demonstrating parallel shift in concentration response curves and estimation of kB
intercept of X plot axis
pkB is equal to the...
log(r-1) = log[B] - log(kB)
Schild equation in logarithmic form
classification of receptors and agonists, assessment of new antagonists
Practical applications of competitive antagonism study...
kB value
Each receptor has a unique..
CR is the same as a well characterised A
It is possible to test if a new agonist acts at a given receptor by examining whether the...
reversible non competitive antagonism
Insurmountable antagonist which binds at site other than that of agonist
hexamethonium
example of RNCA that blocks nicotinic ion channels
open channel block
RNCA can only bind when ion channel is open