By Florian Waser on Wednesday, November 26, 2003 - 10:55 pm:

Hello

I developped a HPLC method for the determination of Dexamethasone and its degradation products in several pharmaceutical formulations. An external laboratory could identify the main impurity peak by HPLC-MS as 17-Ketodexamethasone.
I want to quantify the 17-Ketodexamethasone, so I'm very interested in finding a supplier.
Does anybody know a brand which is specialized on such special substances. The problem is, that 17-Ketodexamethasone is not an impurity of Dexamethasone according the EP or USP (I only have USP 24).
The chemical name of this substance is:
9alpha-Fluor-11beta-hydroxy-16alpha-methyl-1,4-androstadien-3,17-dione, the CAS# should be 1880-61-1.
What I know is that clinical laboratories often have to determine this substance ("17-Ketosteroide") in urine samples, but most of these laboratories use an enzymatic testing kit which determines all 17-Ketosteroids as the sum.

Can anybody help me ?

Florian

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By Anonymous on Monday, December 1, 2003 - 04:03 am:

I know we have tested Dexamethasone in the past and that we didn't use an external standard for the degradates. We just quantified against Dexamethasone itself. The method, as I recall, used hydrogran peroxide and HCl to degrade some dexamethasone to make a system suitability solution so we could identify the degradate retention times. There was also a 17-Acid, Aldehyde, and 21-Hydroxy-Ketone degradate, so you may need to look at quantifying these too.

I don't have access to the method, so can't provide any more details.

Possibly Sigma/Aldrich would stock the degradate material/s, otherwise, you will have to look at doing a semi/prep scale analysis to make it yourself.

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By Florian Waser on Monday, December 1, 2003 - 07:04 am:

Thank you, Anon

I have a method for the synthesis of 17-Ketodexamethasone. And the target is to use such self-prepared substance as a reference substance (because of the very different response factor). So I have to identify the substance (infrared or so) and I need a method for the assay of the substance (UV or so).

So I think a supplier would give me substance AND data all together

Best regard
Florian