[JSM]

We have Desmopressin standard vial with label as 0.98mg per vial. It is available in the form of Desmopressin Acetate . Means in vial actually it will be more than 0.98mg.Desmopresiin acetate molecular formula is as
Desmopressin.acetic acid.3H2O

Molecular weight of Desmopressin is 1069
Molecular weight of Desmopressin Acetate anhydrous is 1129 Molecular weight of Desmopressin Acetate trihydrate is 1183

How to calculate poency of Desmopressin Acetate as is basis.

[Arkcon]

You have to write a ratio, of what you have, and what your procedure requires, and multiply it by what you weigh, to determine the potency of what you prepare.  I hope that's clear enough for you to follow, because we do like to help people to do things for themselves on this forum.  However, you're question is not very clear, I don't really know, what you have, and I really don't know what you need. 

Another way of looking at the problem is to consider anions, and water of crystallization as impurities, that drive your mass down.  You seem to be saying that there will be more in the vial, when it's given that it's the acetate, and that's not correct.  The water of crystallization, I don't know where that enters into what you have.

[JSM]

I want to calculate potency of desmopressin acetate as is basis. I have COA of Desmopressin API. In that they had given potency as below,
Peptide(Desmopressin) as is-87%
As anhydrous, acetic acid free basis-97.7%
Water-2.4%
Acetic acid-5.8%

What will be the potency of Desmopresssin acetate as is basis.
We required for tablet assay calculation in the form of desmopressin acetate.

[JGK]

From the information supplied, I would calculate it as follows:

100 (%) - 2.4 (% water content) - 5.8 (% acetic acid content) = 91.8 %

91.8 * 0.977 (anhydrous purity) = 89.7

[JSM]

Actually I want potency as Desmopressin Acetate as is basis.We are calculating std potency as
=Peptide conetent x 100/100-Acetic Acid content

Is it correct or not because we are getting assay about 93% by using this potency calculation

[JGK]

Actually I want potency as Desmopressin Acetate as is basis.We are calculating std potency as
=Peptide conetent x 100/100-Acetic Acid content

Is it correct or not because we are getting assay about 93% by using this potency calculation

I don't believe it is correct as you are not accounting for the water content in the vial in your calculation, which only addresses the acetic acid content.

Alternatively from the data  supplied it can be calculated from


87 (% Desmopressin as is) x (1129 (mw Desmopressin Acetate)/1069 (mw Desmopressin)) = 91.9 %

[JSM]

Thanks for giving guidance