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Tablets & Capsules October 2014 9 not significantly alter the drug release rate, the physical stability of the dosage form, or the chemical stability of the active ingredient [2]. One of the most common blinding techniques for solid oral dosage forms is over-encapsulation, in which the tablet or capsule is placed inside an opaque capsule and an excipient is added to prevent rattling. This method requires that the product to be blinded fit within the capsule shell and thus it may not be suitable for large products [3]. Furthermore, drug dissolution may be slightly delayed because the capsule shell must begin dis- solving before the dosage unit inside is exposed to gas- trointestinal fluids. In addition, the residual water in a gelatin capsule shell may present stability issues for drug products that degrade by hydrolytic mechanisms [4]. Another over-encapsulation technique, "milling and filling," calls for reducing the comparator to a powder and then filling it into a capsule. This aggressive treatment destroys the original drug product and, due to changes in particle size, can alter the dissolution rate of the drug and influence its chemical stability. Moreover, the process may induce polymorphic changes and destroy any special drug-release mechanism [2, 5]. Overcoating a drug product—covering the unique ink markings on tablets with a water-soluble polymer—has been used as an alternative to over-encapsulation [2]. Intentional bridging of a logo with water-soluble poly- mers has also been used [6]. Obviously, the dosage form must remain stable under the processing conditions, and the coating should not alter the drug-release properties. An alternative to overcoating is de-inking, in which the unique product identification print is removed from the surface. Such a process, if done carefully, should minimize changes to drug release and physical changes to the dosage form. Manual de-inking, however, is very laborious, which has limited its popularity. Recently an automated system was developed that has the potential to remove the ink from tablets and capsules more quickly and with less labor [7]. The objective of the study described here was to eval- uate how this automated de-inking system compared to a manual process in terms of the extent of ink removal and the effect on the product surface. Methods Advil (ibuprofen) tablets, enteric-coated aspirin tablets, and diphenhydramine capsules were purchased from a local pharmacy. These commercially available products were subjected to an automated de-inking process and a manual de-inking process. Automated de-inking. The automated de-inking sys- tem (photo right and on page 8) passes a fabric tape over the surface of the tablet or capsule. Metered amounts of isopropyl alcohol, a solvent, are applied to the fabric tape to accelerate de-inking. Following ink removal, a dry sec- tion of fabric tape passes over the dosage form to remove any residual solvent. Manual de-inking. Tablet and capsule samples were manually de-inked using a cotton swab wetted with ethanol. The cotton swab was squeezed to remove excess liquid. The minimum number of wipes required to remove visual evidence of the identifying print was determined. The Advil tablets required approximately 14 to 18 wipes; the diphenhydramine capsules required 6 to 10 wipes; and the enteric-coated aspirin tablets required more than 80 wipes. Microscopic examination. Representative samples were imaged by light microscopy at 43 magnification using an IX70 microscope (Olympus, Center Valley, PA), and images were captured using Olympus cellSens Dimension software. Samples were also imaged at 1803 magnification using a JSM 5800LV scanning electron microscope (JEOL USA, Peabody, MA) in low-vacuum mode. Sputter-coating was not used. Images were cap- tured with Link ISIS Windows software (Oxford In - struments, Abingdon, UK). Disintegration testing. To investigate the influence of the de-inking process on the functionality of the enteric- coated aspirin tablets, control (unadulterated) and de-inked tablets (n55) were subjected to modified disintegration testing. Tablets were weighed individually then placed for 2 hours in a disintegration apparatus that was dipped in pH 1.2 media equilibrated at 37ºC. Next, the tablets were removed, blotted dry with a lint-free towel, and reweighed. Tablets were then returned to the disintegration basket, and the times to initial disintegration and to complete dis- integration in pH 6.8 media equilibrated to 37ºC were determined. The weight gain of each tablet after exposure to the acidic media was calculated using Equation 1. (1) % weight gain 5 Weight After 3 100 Weight Before Results Examination by light microscopy showed that the majority of ink was removed from both tablets and cap- sules, irrespective of the de-inking method employed, as shown (figures 1 to 3). Small ink spots did remain on the The automated ink-removal system [7]