Time Stamps:
00:00 Resting State of the Receptor and Receptor Activation
01:21 Intrinsic Activity/ Intrinsic Efficacy
03:20 Intrinsic Activity of Full, Partial and Inverse Agonists
09:15 Full, Partial and Inverse Agonists on a bar graph
12:48 Concentration-Response Curve (CRC) or Dose-response Curve (DRC)
14:54 Efficacy and Potency
26:39 Spare Receptors/ Reserve Receptors

The efficacy of a drug is the maximum response achievable from a drug regardless of the drug potency.

Note that a drug may have a high efficacy but not be potent, i.e. the drug may have a high maximal response (Emax) but require a lot of the drug to do so. If an analgesic can relieve hundred percent of a patient's pain but requires 2000 mg to do so, this drug has a high efficacy but a low potency. Conversely, a drug can have a high potency (small amount of drug required to get 50% of the maximal response) but have a low efficacy (partial agonist).

A drug can be less potent but still highly efficacious (Emax = 100%). Do not get confused by this concept. Remember potency and efficacy are independent of each other. Refer to the graphs in this video to illustrate this concept.

This video lecture is on:
#IntrinsicActivity
#EfficacyAndPotency
#FullandPartialAgonist
#SpareReceptors

GraphPad Prism Video:
Title: How to determine EC50 (Potency) in Prism?
Link:    • GraphPad Prism 8 | Finding IC50 value...