Welcome all to IS PHARMACOLOGY DIFFICULT Podcast ! I am Dr Radhika Vijay, in today's episode I will talk about more details and facts about Receptor mediated Drug Action. Receptors can be membrane bound or Intracellular. They bind with specific functional groups of drugs, as well as some endogenous substances. Receptor has 3 D Configuration. Its same as lock and key mechanism. This leads to the formation of DR complex which finally results in the effect. This can be reversible du to Vander waal forces in hydrogen bonds, or it can be irreversible when there are covalent bonds, along with reversible and irreversible binding, there is stereoselective binding, where there is different activity of optical isomers . All these are accompanied with apt examples. Receptors are macromolecular proteins, there are several types of them. If the drug receptor binding does not lead to effect, its not a receptor, its only acceptor or non specific binding site. Then, next I will talk about Affinity, which is capability of drug able to bind with the receptor. Whereas Efficacy or Intrinsic activity refers to the ability to produce a response. On the basis of these two basic concepts, there are different definitions of Agonists, Antagonists, Partial agonist, Inverse Agonist, etc and much more. Before winding up, I will be wishing you all the best and safest, healthiest, brightest season's greetings, yes WISHING YOU ALL A VERY HAPPY DIWALI, till next knowledge talk, do follow me here, stay tuned, do rate and review on ITunes, Apple podcasts, thank you!!