Issue link: https://www.e-digitaleditions.com/i/883179
lasers can mark SODFs after they are sealed in clear blis- ter packaging. One drawback to laser engraving is that it can only leave a medium-to-dark gray marking. Nonetheless, these markings contrast well with most col- ors found on tablets, capsules, and softgels. Beyond the basics of identification Advances in identification technology, coupled with smart phones and other personal electronics, promise to bring the internet-of-things to pharmaceutical tablets and capsules. That means new possibilities for supporting patient care. Clinical trials. Printing data matrix codes onto tablets and capsules at the point of dispensing would help iden- tify and track the experimental drug products, compara- tors, and placebos in double-blind clinical studies. Codes could be read optically by smart phones or other devices and the dispensing data could be transmitted to clinical trial managers in real time. It would even be possible to authenticate that the correct product is being adminis- tered to individual patients/subjects. Tampo printing is essentially a linear stamping process that begins with a stationary etched or engraved metal plate. The plate receives ink from a supply bag or pot and a doctor blade passes over the plate to remove any excess ink. Next, a rubber pad contacts the plate, picking up the ink pattern. The pad then moves into position over an array of oriented SODFs and tamps the ink onto their surfaces. Inkjet printing. This technology is the most recent method to gain acceptance in the pharmaceutical indus- try. There are two approaches: continuous inkjet (CIJ) and thermal inkjet (TIJ), both of which are digital "drop- on-demand" techniques. They offer the greatest versatil- ity in terms of printing schemes and colors, complex logos, and machine-readable codes. The only limitations are the print head's resolution and choice of inks. With either method, you can easily change the print format and/or data sequencing using software. Because both apply ink without contacting the tablet or capsule, inkjet printing offers an alternate to debossing uncoated tablets, some of which are too soft for debossing. Certain orally disintegrating tablets, or ODTs, are one example. CIJ. With CIJ printing, a recirculating stream of ink is supplied to a nozzle that applies it to the tablet or cap- sule. Any ink that isn't used for printing enters a return gutter and flows back to the ink reservoir. To produce the ink droplets, the print head vibrates using a piezo- electric crystal. These are deflected by energized elec- trodes and impinge on the product's surface. This hap- pens extremely fast and produces precise, sharp imprints with good resolution. The bulk of the ink used in CIJ printers recirculates continuously, which leads to solvent loss through evaporation. To ensure consistent print quality, a control loop based on ink viscosity is used to add makeup solvent. TIJ. This is the newest approach to printing on tablets and capsules. TIJ printing uses a compact cartridge that operates on a principle similar to that of the cartridges home and office printers use. The cartridges feature an array of miniscule chambers, each with its own electrical heating element. When an electric pulse passes through an element, heat instantly vaporizes ink in the chamber, causing expansion and a rise in pressure, which propels ink droplets onto the product. The ink remains in solu- tion inside the cartridges, which have no moving parts and require no external supply of ink. This greatly reduces volatile organic compounds at the point of use. Laser engraving. As a digital technology, laser engrav- ing also allows you to create images using software. The software interfaces with a control system to operate a series of high-speed mirror galvanometers that redirect the laser beam into the desired pattern. Lasers operating in the UV spectrum create their mark by oxidizing an excipient, tita- nium dioxide, which effects a change in the oxidation state of the titanium. This releases oxygen atoms and changes the excipient's color from white to gray. Laser engraving provides well-defined, indelible mark- ing, depending on the nature of the SODF surface. Some 36 October 2017 Tablets & Capsules This thermal inkjet printer provides digital print-on-demand capabili- ties. Imprints can be made using its design software or by uploading files created in Adobe, Corel, or other programs. The printer uses an inkjet cartridge that eliminates the ink pots, change parts, and prod- uct-specific design plates that traditional roll and pad printers require.