True statement regarding inverse agonists is-
Ans. is 'b' i.e., Binds to receptor and causes opposite action o Receptors are specific binding site with functional correlate,o In relation to action through receptors, two terms are important.i) AffinityAbility of the drug to combine with the receptor.It determines the concentration of drug required to form a significant number of drug-receptor complexes.ii) Intrinsic activity (efficacy)Ability' of the drug to activate (induce a conformational change) in the receptor.Based on their intrinsic activity drugs may be divided in to :AgonistAntagonistPartial agonistInverse agonist----Have both affinity and maximal intrinsic activity.Have affinity' but no intrinsic activity.Have affinity and submaximal intrinsic activity'.Have affinity but opposite intrinsic activity' ie intrinsic activity with a minus sign. AgonistAntagonistPartial AgonistInverse Agonist----Affinity + Intrinsic Activity +Affinity + Intrinsic Activity 0Affinity - Intrinsic Activity 1/2 +Affinity' + Intrinsic Activity -
Binds to receptor and causes intended action
Binds to receptor and causes opposite action
Binds to receptor and causes no action
Binds to receptor and causes submaximal action
C.N.S