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Thank you for all your responses. The overwhelming response was that the gluten in zithromax is probably from corn which would not be a concern. However, others said I should ask what the source is when I call. So I called Pfizer again this morning and spoke to a pharmacist who could only tell me is that it is not from gliaden (wheat) and they are not able to go further and tell me whether it is from rye, barley, oats, or corn for that matter..

So now what? I am not sure whether to consider it safe or not. I am trying to reach the doctor to see what alternatives may exist.

I also got some explanations of gliaden from people which I am copying here...

You're right about gliadin, that's the wheat protein fraction that's 
toxic to celiacs. Hordein in barley and secalin in rye are the others.
The suspect ingredient in Zithromax is the pregelatinized starch. If 
it's made from corn, it could contain corn gluten which is of no concern to celiacs. Too bad they don't specifically reveal the source, that would really clear things up.


This should answer your question about gliadin,etc.  It is from CSA/USA 
website www.csaceliacs.org
The Damaging Proteins
The term "gluten" is, in a sense, a generic term for the storage proteins that are found in grains. In reality, each type of protein - gliadin in wheat, secalin in rye, hordein in barley, avenin in oats, zein in corn and oryzenin in rice - is slightly different from the others. The "gluten" in wheat, rye, barley, and in a much lower amount, oats, contains particular amino acid sequences that are harmful to persons with celiac disease. The damaging proteins are particularly rich in proline and glutamine (especially the amino acid sequences which are in the following orders: Pro-Ser-Gln-Gln and Gln-Gln-Gln-Pro). As peptides, some such as 33-MER, cannot be broken down any further. In people with celiac disease, 33-MER stimulates T-cells to produce antibodies. The antibodies, in turn, attack the villi in the small intestine, reducing their ability to absorb nutrients. It is important 
to note that these sequences are NOT found in the proteins of corn and rice.


I mentioned the plant scientist at the USDA in Albany, CA that had done lots of research on gluten and gliadin. Here are some links to the explanation of gluten (an often over-used word) and gliadin (the fraction of wheat gluten that is damaging to celiacs): 
Good overview. Somewhat technical: http://www.aaccnet.org/grainbin/kasarda.asp
If you believe spelt is safe, then this article will change your mind: http://www.aaccnet.org/cerealchemistry/abstracts/1999/0526-02R.asp
When Kasarda retired, he wrote this summary. It is very good: http://wheat.pw.usda.gov/ggpages/topics/celiac.html
This article mentions the role of gliadin: http://www.aafp.org/afp/980301ap/pruessn.html
Here is an article that sums up vurtually everything known about gluten and gliadin. I think it is a FDA draft: http://www.twincitiesrock.org/documents/FDADraft.pdf
If you read only one article, read the middle one


Cheryl

Visit the Celiac Web Page at Http://www.enabling.org/ia/celiac/index.html
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