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The FDA determined that NanOss is “substantially equivalent” to other resorbable calcium phosphate bone void filler devices because its intended use, design, and functional characteristics are substantially the same as previously approved devices, each of which was intended to fill gaps in bone, was not intended to be load-bearing, and consisted of calcium compounds. Yet the USPTO granted a patent on NanOss covering both the nanocrystals and the method of producing them.
Antimicrobial silver wound dressing is another product that employs nanotechnology, has FDA approval, and has been patented. NUCRYST Pharmaceuticals, a publicly held company in Wakefield, Massachusetts, uses a patented process to isolate silver-containing nanoparticles, which are then placed on a substrate of polyethylene mesh as atomically disordered nanocrystals. The substrate is used in wound and burn care products.
The FDA determined that the dressings are “substantially equivalent” to prior silver-coated dressings that release silver ions into wound sites to provide an antimicrobial effect. Yet NUCRYST holds numerous patents that cover the manufacturing process, as well as compositions of matter (including coatings, powders, and flakes) and uses that incorporate the technology.
If NanOss and nano-sized wound dressings are substantially equivalent to larger versions of the materials, as the FDA has found, an infringer might be able to challenge the patent on the grounds that the inventions are not novel. Alternatively, if these products are novel—and potentially create new risks—the FDA should be paying closer attention.
Public interest groups are petitioning the FDA to reconsider its position that the nano versions of products behave in the same way as the larger versions. In July 2007, an FDA taskforce recommended that the FDA seek public comments on which property changes in nano materials could lead to concerns about safety and efficacy. This is now playing out on our beaches and ski slopes, because the FDA determined that nano-sized particles of titanium dioxide and zinc oxide, ingredients commonly found in sunscreen, are substantially equivalent to their larger-sized counterparts. The small size of the nanoparticles gives sunscreen what seems to be a novel property—better absorbability, which reduces the white skin appearance that otherwise results from these compounds. But small size also raises health concerns.
As particle size decreases, there can be an increased evasion of the body’s natural defense mechanisms. Inhaled or injected nanoparticles can enter the blood and lymph system and migrate to other organs, tissues, and the nervous system, raising concern that they may cause damage. Certain nanoparticles can also cross the blood brain barrier—a function which could be beneficial for drug delivery to the central nervous system, but which could also cause harm to neural tissue.
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