Purity is a measure of how much of some substance is “what it says on the tin”. Potency in contrast refers to the dose necessary for a substance to exert its effect on the body.

What does the purity of the drug mean?

Purity is the measurement of the quantity of a prevalent component of a drug substance when only that component is present. The purest material is generally regarded as a reference standard and is used to determine the purity of a drug by a comparative UV spectroscopic method.

What is as potency?

A Potency (as Is) factor will have accounted for all of the measured moisture and impurities in that particular batch.