Chromatography Forum

Hi. I am new to HPLC and would like to know some information about developing a stability indicating assay. Following the stress studies and the separation of the peak of interest form the degradation products, do we need to identify and quantify all of the degradation products of a compound? What happens if there are no reference standards available for the degradation products and there is no information on the degradation pathways of the drug in the literature?

Thank you

It depends upon the level of the final product and the probability of the API yielding toxic degradants.

If the active ingredient is in a topical product, then maybe not have to identify all degradants. When I validated a stability indicating assay where the API was in a teat dip, I did not have to identify the degradants.

When the final product was a GMP manufactured injectable; then, I had to make efforts to identify the degradants. For example, I had a project where I had to convert a HPLC assay to a LC/MS compatible assay in order to elucidate probable degradant structures. I fraction collected the degradants from the original HPLC assay, then analyzed the fractions by the LC/MS compatible assay.

In another instance, the API was in a GMP injectable final product, and there were no literature references on the degradation pathways. I contacted the manufacturer, who could not find literature references either. So, I did 'chemistry.' I wrote out the equations to figure out possible degradant structures.

Then, I scoured through literature and vendor websites to find these structures. In the end, I found a few of the possible degradant compounds through commercial sources. I also used the 'related compounds' approach, wherein I purchased compounds that were closely related in structure and characteristics to the possible degradant structures. I, then, analyzed all these possible degradants and related compounds to show specificity and stability indication of the assay.

Thank you for your answer. There seems to be little information about the specific requirements for each product. I will be working on a transdermal dosage from. So most likely I would need to identify the degradation products !!

I agree with you. A transdermal could potentially carry degradants across along with the API.

Also, if you work in a cGMP regulated environment, you may be able to contact your local regulatory district for advice. This approach has been helpful to me in the past.

If the active ingredient is in a topical product, then maybe not have to identify all degradants. When I validated a stability indicating assay where the API was in a teat dip, I did not have to identify the degradants.

Sally - do you have an official document reference that states one does not need to identify degradants in a topic product (especially a wash-off prouct) ? Thanks.

Sorry, but that project was six years ago, and I don't remember if I found a regulatory document and / or relied on advise from our regulatory district. This is why I mentioned contacting the local regulatory district for their view on the extent of validation for that particular formulation.