Efficacy and Receptor Reserve

The role of agonists and antagonists in the effectiveness of pharmaceuticals as taught in undergraduate pharmacology. This video is designed as a revision aid for students as well as to support teachers in the classroom.

[@syedrizvi539]

amazing analogy keep it up

[@shangfanggao6880]

Excellent elaboration!

[@blasphemyjg]

might need to look at that analogy. If you add 4 more new batteries in series like shown, you'll most certainly increase the brightness of that torch as you will have doubled the voltage supplied to the torch.

[@dianagriniouk3243]

Super useful!

[@alistermcneish8148]

This is not strictly true partial agonists can achieve 100% occupancy and never evoke the maximal response - its a defining feature of partial agonists and is experimentally borne out in tissue

[@shahadyagoub5143]

He never denied this fact !! he specifically said with partial agonist by increasing the amount of the drug you might have a chance to increase the response while this chance it’s not possible at all with full agonist so he was basically comparing the two. he never said that increasing the amount of a partial agonist Will for sure achieve maximal response at some point

[@alistermcneish8148]

​@@shahadyagoub5143 It is implied in the video that by adding more partial against you have a greater chance of obtain the maximal response if there is a large receptor reserve - that is simply not the case: by definition a partial against will *never* the cause a maximal response even if 100% of receptors are occupied (even in tissues where receptor reserve is high). If it could evoke a maximal response it would not be a partial agonist. In fact some partial agonists can evoke their greatest submaximal response at very low receptor occupation and (just like full agonists that produce a maximum response at low occupation) adding more of the partial agonist will not cause a bigger response. Thus in many cases receptor reserve may not be important in the action of partial agoninsts. Receptor reserve is better explained in terms of occupation by looking at the effects of irreversible competitive antagonists that permanently occupy the "reserve receptors" by measuring the number of receptors required to be occupied to reduce the maximal effect of a full agonist we then reveal the receptor reserve.

[@DrAndyHolt]

Whether or not an agonist is a partial agonist or a full agonist depends on the tissue and the level of receptor expression in the tissue. A drug can be a partial agonist in one tissue and a full agonist in another tissue that expresses a higher number or density of receptors.

[@gugulothuday8137]

Nice 3d