Packaging Forum

Identifying Marks (continued)

Combination techniques A multifaceted anticounterfeiting solution—which consists of a combination of visual, electronic, chemical, flavor, and aroma identification—allows overt and covert tools to work in tandem, thus providing drug makers another safe way to protect their products from counterfeiters. For example, a visual tool such as a hard-to-duplicate pearlescent coating may be combined with an electronic identification tool such as a two-dimensional bar code or a covert barrier (i.e., edible chemical markers that are invisible to the naked eye). In addition, flavor and aroma film coating additives provide unique profiles and an additional level of authentication. Film coating, colorant technology, and high-definition printing and imaging systems are central to the implementation of these tools. Transitioning to one or more of these technologies may necessitate an investment in printing and scanning equipment, but should add only a fraction of a cent per tablet in material costs (Security inks and coatings, Colorcon, West Point, PA). Pearlescent coatings are available in several custom colors and provide a distinctive appearance that enhance product branding and provide positive identification at all supply chain levels. Strictly controlled production secures supplies. Several bar code inks have been tested and proven to reproduce scannable Data Matrix codes. Successful combinations include white ink on a purple film coat, black ink on a red film coat, red ink on a yellow film coat, and black ink on a white film coat. Code size and tablet shape also affect scannability. Tests show that the minimum size for a Data Matrix representation of a national drug code ranges from 2.5 mm2 for a flat tablet to 4.0 mm2 for a solid dosage form with complex curves. Bar codes can be combined with logos or numbers to enhance recognition. With today's high-resolution printing, logos can  even incorporate coded images to provide a product fingerprint (i.e., a covert chemical marker added to the film coating). Such a marker provides a means to authenticate the two-dimensional code and might contain additional information such as manufacturer, expiration date, and distribution channel. Ink-jet printing. Food-grade inks combined with an ink-jet printing system capable of high-definition microprinting can produce alphanumerical, two-dimensional codes with print heights of 0.8 mm. Such systems accommodate product moving at 308 m/min. (Pinpoint inkjet coder with food-grade ink, Domino Printing Sciences PLC, Cambridge, UK). Variable data can be printed on tablets using thermal inkjet technology and food-grade inks. Printing may take place on- or off-line. Variable data not only provides an authentication tool, but also enhances track-and-trace capability to meet electronic pedigree initiatives (Print-on-tablet technology, HP, Palo Alto, CA). Additional two-dimensional codes. Other two-dimensional codes also have potential for tablet marking. The technology behind these printed codes is based on image recognition principles and chaos theory. The printed marks may be applied to smooth, rough, curved, or flexible surfaces by means of laser. Data capacity ranges from 7 to >30 d; codes as small as 0.1 mm, which is invisible to the naked eye, can be produced. Scanning requires a contrast of less than 10% between the code and its background and may be performed at speeds as fast as 12,000 codes/h with commercially available equipment (2DMI, ORBID Corp., San Francisco, CA). Data matrix and other two-dimensional codes require camera-based readers rather than the laser-based scanners typically used with linear bar codes. Numerous suppliers provide camera-based readers. When selecting equipment, however, drug makers must match features to the coding task. Bar codes that are not readily visible to the eye may require readers with enhanced capabilities such as high-resolution scanning (AutoProof Pro, Complete Inspection Systems, Intelligent Scanner XS, DVT Machine Vision, Duluth, GA). Other techniques. Electrostatic coating, another brand protecting and enhancing technology, relies on the same principles as photocopying. A conductive tablet core receives an electrostatic coating, which is then fixed in place with heat. A variety of patterns or alphanumeric characters can be created in contrasting colors (UniQ brand protection, Phoqus, West Malling, Kent, UK). To help drug manufacturers design solid dosage forms that are difficult to counterfeit but do not extend the design cycle, a global network of design centers supports on-site or remote collaboration among team members. Key to the system is proprietary software that displays two-dimensional images of the evolving tablet design. Facilities in West Point, Pennsylvania; Dartford, United Kingdom; and Goa, India; will be joined by the end of 2005 by design centers in China and Japan (Colorcon Global Tablet Design Centers, Colorcon). PT