Assay calculation for lyo product

[domino1]

Hi all,

Just wanted to know how you all handled this.

We have a lyo product and were looking at two options for the assay prep/calc.

1. Quantiatively transfer the cake to a volumetric flask and do everything wt/vol.

2. Do wt/wt and then use a density factor to convert. The issue here is that you assume that the cake has a certain wt and that the density is consistent since you are basing it on a perfect cake scenario. Or, you can verify the weight of the cake after the assay by doing the vial wt before and after to get the actual cake wt, but you still would be using the theoreitcal density since you can't measure that every time (at least it would be too cumbersome for this project).

Let me know your thoughts.

thanks!

Domino

[AdrianF]

More explanation required! What is a lyo cake?

[domino1]

A lyophilized drug product (rather than a liquid).

Sorry!

[AdrianF]

I would transfer the dissolved cake quantitatively to a volumetric flask and then assay.

You will then discover how many ug/mg of active you had in your vial. I see no need for any weights/densities to come into it.

It is rather like an individual tablet assay.

It would be useful to know the weight of the cake as well so you can decide if any out of spec assay relates to the weight of cake.

[markreyes]

I ageee with dissolving and transferring to a vol flask to get assay value. it should already be pre determined what your fill volume is and the concentration of your product before you lyo your product. With these number you can calcualte recovery.

In addittion to doing the assay, you might want to do content uniformity also.