By Steven A. Melman, VMD
Tris EDTA (TrizEDTA tm, DermaPet) has a mechanism of action, chemical description and method of usage well described in the Pseudomonas in Ear Disease article by Foster and Deboer appearing in the Compendium, August, 1993. As it pertains to TrizEDTA, this article appears at this website along with a diagram of the gram negative bacterial cell wall.
The Mechanism of Action is to chelate minerals (MG+++) from the bacterial cell wall. Although it alone is bactericidal, it is most often used with aminoglycosides and fluorquinolones with which it is synergistic. Personally, I am concerned about the use of aminogycosides in the ear due to ototoxocity. It has also been reported to be useful in the bladder, eye, nose, skin, and ruminant teats (for mastitis).
TrizEDTA (patent pending), a 4 ounce container to which 112 ml of distilled water is added, is composed of Tromethamine USP (Tris) 533 mg, Edetate Disodium Dihydrate USP (EDTA) 141 mg, buffered with Tromethamine HCL to a pH of 8. Readers will note the similarity of this product to those published using lesser quality, laboratory ingredients. While this appears easy to make (to one who chose to not honor the patent that is pending), most assuredly it is not, as the precisely weighing the ingredients, mixing and pH buffering is very difficult.
The method of usage is to place the TrizEDTA in the ear or chosen site of usage. Ideally, one should wait 15 minutes and apply an antibiotic of choice. My preference is Baytril. I also use a systemic antibiotic. Deboer has described instilling tris edta long term, a few times a week, in Pseudomonas cases.
There are many articles by Woolley and others which are referenced at the web site.
Steve Melman VMD
DermaPet
Animal Dermatology and Behavior Clinics
http://www.dermapet.com
301-365-0191 fax
301-983-8387
8909 Iverleigh Court 
Potomac, Maryland 20854
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