Welcome all to IS PHARMACOLOGY DIFFICULT Podcast ! I am Dr Radhika Vijay, in today's episode, wishing all a very happy DIWALI!!! Now I will be talking about Agonists, Antagonists etc with regard to Affinity and Efficacy. Agonists have affinity and Intrinsic Activity which is maximum i.e. equals to 1. Antagonists, competitive ones have affinity and Intrinsic activity equals to 0(zero). Partial agonists have affinity and Intrinsic activity somewhere between 0 and 1.  All have their unique examples. Antagonists interfere the binding of endogenous agonists. Teaser of dual nature of receptors is given. Partial agonists have higher affinity and are more potent than full agonists but being partial agonists, they cannot produce maximum response, though they occupy a large number of receptors. Inverse agonists have affinity and intrinsic activity is between zero and minus one(0 and -1). They have constitutive activation, i.e. tonically partially active, even in absence of drug. Maximal response is produced by agonists even after occupying minimum number of receptors, in such case a large number of spare receptors is present. All these situations are affected by so many factors like presence or absence of drug etc. That was all for the day folks, till next episode, do follow me here, stay tuned, do rate and review on ITunes, Apple podcasts, thank you!!