[e-drug] Chromatographically purified vancomycin? (6)

e-drug
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E-DRUG: Chromatographically purified vancomycin? (6)
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dear e-Druggers,

As a non-scientist, I don't have a response to this, but I did share
the query with an experienced analytical chemist. Below is his
response. Bear in mind that this is a general reply, he has not studied
the specific case regarding vancomycin.

Chromatographic purification is a reasonable step that I would think
all pharmaceutical manufacturers use in preparing their drugs. If it
is important that only a specific ingredient, from a mixture of
compounds, be collected for subsequent use (blending with excipients
or other important ingredients), then some form of purification is
required. Chromatography is often used when other procedures, such as
distillation, cannot, and it can be scaled up for bulk methods.

But, because chromatography is so common, I suspect, making it a
requirement in a tender seems silly to me. Instead, the chemical
industry usually guarantees product quality by assay, after the fact,
which is more reliable. A company that produces a product with a
chromatography purification step could still produce bad product.

regards

Joana Ramos, MSW
Cancer Resources & Advocacy
Seattle WA USA
+1-206-229-2420
http://ramoslink.info/
www.bmtbasics.org
www.healthyskepticism.org

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E-DRUG: Chromatographically purified vancomycin? (7)
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Dear E-druggers:

As a former analytical chemist for a U.S. biotech company, I agree with
Joana's friend.

Purification by chromatography does not eliminate all impurities -- it
depends on the substrate characteristics (such as pore size, substrate
type, etc.), the carrier solvent characteristics (mixture, gradient
used, etc.), and several other factors. These methods then need to be
validated through extensive testing, comparison to standard compounds,
and subsequent analysis.

If they mean vancomycin has been analyzed by chromatographic method
assays, then this is another issue entirely. Liquid and gas
chromatographic instruments - especially HPLC, GC, GC-MS - are extremely
sensitive and serve as Quality Control mechanisms in many biotech and
pharmaceutical companies - and of course in the U.S. Pharmacopeia and
other reference documents. This type of analysis could potentially add
value to the vancomycin in question.

Like Joana's friend, I am not familiar with the specific manufacturing
process and analytical methods used for vancomycin. I can only comment
on the general principles involved.

Cheers!

Scott Ruschak, MPH, MA
Senior Manager, Medicines Program
MAP International
SRuschak@map.org