Potency: Please help me understand

[gfeldman]

I'm new to the forums, so hello all and thank you for your advise and input in advance. I have been given a compound with ~77% potency (as I am told). I am rather confused as to what this means though. Does this mean that when I run the sample and receive a peak area, that area corresponds to 100% of the compound that is only 77% active? Or, the peak area is only 77% of the actual compound that was loaded (so it would be more like a percent recovery)?

If potency is really just % recovery then it can be calculated "theoretical in/total measured". If it has to do with actual active compound though, certainly it can not be measured by HPLC can it?

Please forgive my lack of knowledge on this, I cant seem to find anything covering it in my HPLC book and I was embarrassed to ask about it at work!

Advice and explanations appreciated!

[Karen01]

While i'm not sure, I would assume that if it's drug substance the API is only 77% of the weight of the powder, and if it's drug product that the dosage form only has 77% of label claim for the API.

If it has to do with actual active compound though, certainly it can not be measured by HPLC can it?

Sometimes the active is a metabolite of the API... but for drug production (at least for small molecules) it's all about the amount of the API that winds up in the dosage form. The correlation with biological effects to establish safety and efficacy for dosage levels of API is what animal and clinical trials are about.

- Karen

[krigan]

Consider just that the area received is 77% of the total substance.

for example 100mg of a substance produces 1000 of área.

Consider that 1000 of área is due of the 77mg of the active and the other 33mg are not active.

[cody84]

I would consider 'potency' as percent active ingredient weight by weight. (In other words, label claim).

However potency means the activity itself...so maybe; of XXX % or weight of the active from the label claim, 77% of that is actively potent as a drug.

I t hink USP has a glossary for potency.