Potency & efficacy

Potency & efficacy

Efficacy:The effect produced by drug is called efficacy.

·         Amiloride cause 5%  excertion→Low efficacy.

·         Thiazide cause 10%  excertion→Moderate efficacy.

·         Frusemide cause 25%  excertion→High efficacy.

Potency:Any response or effect of a drug by a fixed dose is called potency.It is expressed in w/w.Potency is influenced by-

·         Absorption.

·         Distribution.

·         Biotransformation.

·         Excertion of drug.

Difference between potency & efficacy:

Potency	Efficacy
1.Potency does not help to choose among drug.	1.Efficacy help to choose among drugs.
2.Potency determine the administered dose of the choosen drug.	2.Efficacy determine clinical effectiveness of a drug.
3.Potency≡Affinity	3.Efficacy≡Intrinsic activity
4.Potency is affected by affinity of receptors for binding the drug and also by efficiency of drug receptor interactions.	4.Efficacy may be affected by the characteristics of a particular drug receptors interaction.
5.Clinical significance:important in durgs of low theraputic index.	5.Important in clinical effectiveness of a drug