Pharmacology 1

Front 1

Mechanism by which an antagonist drug might affect a rceptor

Back 1

Inhibit endogenous cell signalling

Front 2

Classical receptor theory/occupancy model

Back 2

As Substrates Bind Reversibly to Enzymes,

Drugs Bind Reversibly (usually) to Receptors
States that the action of a drug on a receptor is directly proportional to the concentration of the drug-receptor complex,[DR]

Front 3

units of rate of association of a drug

Back 3

units of k1 are M-1min-1

Front 4

units of rate of dissociation of a drug

Back 4

units of k2 are min-1

Front 5

KD (binding constant)

Back 5

is a measure of affinity of drug for receptor

Front 6

Equation for KD

Back 6

K2/k1
or
conc.of Drug(D) multiplied by conce.of Receptor(R) ,then divided by conce. of Drug-Receptor Complex(DR).
The units of KD are moles/liter

Front 7

T/F. At equilibrium the rate of drug receptor complex formation is equal to the rate of drug receptor complex dissociation

Back 7

True

Front 8

Receptor Occupancy Equation

Back 8

DR = Rt [D]
----------
KD + [D)

Front 9

Which is true?
A)The KD of a drug for a given receptor is the same.
B)A drug with a highest kd will have a a lowest affinity.
(C)Two drugs acting
at the same R can produce different magnitudes of response if and only if
they have different affinities (KD) according to the occupancy model.
D)All are true.

Back 9

D)All are true.

Front 10

T/F. Generally Drug response IS NECESSARILY
directly proportional to occupancy

Back 10

False.Drug response IS NOT NECESSARILY
directly proportional to occupancy .Since “occupancy model” does not hold for effect vs. [D] but occupancy vs. [D]