Question

What is the difference between an agonist, partial agonist, antagonist and inverse agonist? Use an example of a psychiatric drug from each category explaining the mechanism of action.

Answer 1

Answer :

Agonist : it is chemical that binds to a receptor and activates the receptors to produce and biological responses , that means it is responsible for any action in the body.

Antagonist : it is opposite to the agonist, it blocks the action of agonist.

Inverse agonist : it is an agent that binds to the same receptors as an agonist but what ever the pharmacological response from it that is opposite to the agonist.

These are the difference between agonist, antagonist, inverse agonist.

Example :

Lithium is an anti psychotic medication, it is used for bipolar disorder, it is dopamanergic agonists or antagonists.

Mechanism of action :

It inhibit the exietary neurotransmitters those are dopamine and glutamate and promote the GABA medicated neurotransmission, finally it is agonist to the dopamine receptors.

Lithium is vasopressin receptor antagonists,

Opioid antagonist nalaxone or naltrexone are partial inverse agonist at opioid receptors.