What are the so-called "ancillary ingredients" in AMO's Complete MoisturePLUS?
Posted by
Armand RossettiJune 15, 2007 7:44 PMTags:
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On April 13, 2005, the FDA approved AMO's Complete MoisturePLUS. This time, AMO represented that Complete MoisturePLUS was "the same as the currently marketed solution." But it wasn't just like it, because MoisturePLUS contained two additional ingredients, propylene glycol (used as antifreeze in automobile radiators) and taurine (used as a specialized buffer).
On two prior occasions, AMO had submitted 510(K) summaries to the FDA for marketing approval for Complete brand Multi-Purpose Solution. The FDA approved the first 510(K) on February 12, 2003 , and the second on April 4, 2003. The second summary stated a comprehensive device description, listing the following ingredients: a sterile, isotonic, buffered, solution containing hydroxypropyl methylcellulose as a lubricant preserved with polyhexamethylene biguanide 0.0001%, a phosphate buffer, Poloxamer 237 as a surfactant, edentate disodium as a chelating agent, sodium chloride, potassium chloride, and purified water.
Hydroxypropyl methylcellulose is mainly used as dispersant in the production of PVC and as thickener, stabilizer, emulsifier, excipient, water retention agent, film-forming agent in petrochemical, building materials, agrochemical, ink, printing and dyeing of textile, paper making, cosmetic, etc. The "etc" must also include contact lens solutions.
What was missing in this picture when AMO decided to file another 510(k) for FDA approval of Complete MoisturePLUS Multi-Purpose Disinfecting Solution?
In its 510(k) submission, AMO presented the FDA with following generalized device description for Complete MoisturePLUS: "a sterile, isotonic, buffered, solution containing lubricants, preservatives, buffers, surfactants, ancillary ingredients, and purified water."
AMO's above-described scant description ensured that the FDA would have no clue that additional ingredients were included in a new formulation, much less any indication that MoisturePLUS was not "the same as the currently marketed solution," i.e., Complete brand Multi-purpose Solution.
What about taurine? AMO probably added taurine to protect the corneal surface. Taurine is an osmoprotectant that increases osmolarity. Increased osmolarity can cause Acanthamoeba to encyst (a protective mechanism) but taurine may help keep the cell active longer. This could thus increase Acanthamoeba's reproductive cycle and the potential for infection; the extent of the increase in the reproductive cycle would depend on the taurine concentration.
Was there a formulation design problem at AMO? Taurine can be used as a component within a medium to grow Acanthamoeba cysts. Taurine Acanthamoeba cysts are harder to kill with PHMB, which is the disinfectant that is found in Complete MoisturePLUS.
Propylene glycol is an eye irritant when not diluted. Did AMO conduct studies that addressed just how much potential the propylene glycol in Complete MoisturePLUS had to irritate the eyes? Did AMO test propylene glycol's cumulative affect on the corneal tissue over time?
Why did AMO describe propylene glycol in the Complete MoisturePLUS FDA 510(k) submission for approval, as an "ancillary ingredient" and taurine as just another "buffer" and portray the new solution as being the same as the preceeding older solution, i.e., the "predicate" device. Perhaps AMO can kindly and swiftly provide the answer.