U01.05.010 Efficacy vs potency

Definition: The maximal effect a drug can produce, regardless of the dose.
Representation: Efficacy is typically represented by the y-value (Vmax) on a dose-response curve.
Key Points:
- Full agonists produce the highest efficacy (i.e., they reach Vmax).
- Partial agonists have lower efficacy than full agonists, even if the drug concentration is similar.
- Efficacy is unrelated to potency. A drug can be highly efficacious but have low potency, or vice versa.

Drug	Maximal Effect (Vmax)	Efficacy
Drug A	Vmax	High
Drug B	Vmax	High

Definition: The amount of drug needed to produce a given effect, typically measured by the concentration at which 50% of the maximal effect is achieved.
Representation: Potency is represented by the x-value (EC50) on a dose-response curve.
Key Points:
- Potent drugs require a lower dose to achieve the desired effect.
- The left shift of the dose-response curve indicates higher potency (lower EC50).
- Potency is unrelated to efficacy; a potent drug may have either high or low efficacy.

Drug	Effective Concentration (EC50)	Potency
Drug A	EC50	High
Drug B	EC50	Low

Efficacy reflects the maximal achievable effect of a drug and is shown by the y-value (Vmax) on a dose-response curve.
Potency indicates the amount of drug required to produce a given effect and is shown by the x-value (EC50).
The Vmax (efficacy) of one drug can be higher than that of another, regardless of their potency.
A leftward shift in the dose-response curve represents increased potency, meaning less drug is needed to achieve the same effect.

Efficacy Curve:

Drugs A and B may have the same Vmax (efficacy), but Partial agonists will have a lower maximal effect than Full agonists.

Potency Curve:

Drug A with a left-shifted curve is more potent than Drug B, requiring a smaller dose to achieve the same effect.

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