Issue link: http://www.e-digitaleditions.com/i/883179
44 October 2017 Tablets & Capsules ent, making these poSi particles excellent candidates for use in phar- maceutical and nutraceutical prod- ucts as unique identifiers. Optical microtags are a promising poSi PCID technology that has recently been developed. These are fabricated using a silicon wafer anodization technique that is well understood and, therefore, allows for easy control of the formation of poSi materials on a large scale. And because they are manufactured from high-purity, semiconductor-grade sil- icon wafers, the impurity profile is similarly well understood and con- trolled, typically within the low ppm or ppb level. Microtag identification technol- ogy is based on fundamental optical filter technology. The pores can be etched into the silicon wafer in such a way that, when illuminated by white light, a specific, pre-selected optical reflectance peak (color) results. This specific color reflectance can easily be discerned by a spec- trometer, or even your eye. The entire wafer surface is etched identi- cally, after which the surface layer is removed and broken into fine parti- cles, thereby producing millions of microtags from each etched layer, with each of those micro-particles reflecting the same color pattern. As you can imagine, a single color of reflected light is not particularly secure since one could use any mater- ial with a unique color reflectance (e.g., glitter) and replicate that effect. The poSi microtag security feature comes from other elements of the poSi product, whereby multiple reflectance peaks—from ultraviolet to infrared—are etched into the micro- tags, thereby creating a unique, multi- color, optical "signature." This feature is analogous to the number of bits in encrypted data. The more bits there are, the more combinations exist and the more difficult it is to crack the encryption. Depending on the level of security needed for a given applica- tion, you can specify the number of color reflectance peaks the microtag will include. In addition to the optical peaks encoded in the poSi microtags, other characteristics of the reflectance (optical spectrum, amplitude, disper- sion), as well as the application (loca- tion, density) can be included to pro- vide multiple levels of security, making this technology virtually impossible to counterfeit. The application of the optical microtags to SODF products is done using existing methods, such as pan coating for tablets and blending and encapsulation for capsules. Because the number of tags required to accu- rately verify a single dose is low, there is virtually no impact on the product's manufacturing process, dosage form, function, or elegance. • For pan-coating applications, the microtags are blended directly into the tablet's outer coating formu- lation for integration via the spray coating process. • For addition to capsules, the microtags are blended into the formu- lation just prior to encapsulation and are filled directly into the capsules. These microtags are covert, can be incorporated into or onto SODF products as well as bulk powder products, and their use levels are far less than 1 percent, making them easy to integrate into existing prod- ucts and processes while remaining cost-effective for the manufacturer. Furthermore, because each batch or lot of SODF products can have a unique signature, and because the microtags on secured products can be scanned and decoded in seconds, countermeasures can be initiated immediately. This can prevent potentially harmful counterfeit prod- ucts from reaching consumers and allow law enforcement to more quickly identify the perpetrators. The development of these optical microtags using excipient-grade silica provides a low-cost, highly secure on-dose identification solution. It offers manufacturers a new tool to combat the pandemic of pharmaceu- tical counterfeiting and diversion, and protects patients from poten- tially tragic consequences. Application to drug delivery Enhancing the solubility of APIs. PoSi has been shown to improve oral bioavailability of poorly water-solu- ble APIs. Because oral administration is a preferred method of drug deliv- ery, it is critical that APIs achieve sys- temic absorption when ingested. That means it must be present in solution in the gastro-intestinal tract so it can be absorbed by the intestinal walls. Unfortunately, many APIs have low solubility in water, which poses a significant challenge to making it available for absorption. By deposit- ing such APIs onto poSi particles, it is possible to improve the dissolution rate of many of these low-solubility molecules. Intercellular nanoparticles. Mesoporous silica nanoparticles are another area of interest because they can be taken in by individual cells through endocytosis, and deliver their payload there. The benefits of such delivery are potentially huge since the particles, once inside the cell, can be functionalized to target specific cellu- In addition to identifying products, porous silica can provide sustained release of actives to targeted locations.