Issue link: https://www.e-digitaleditions.com/i/1287521
22 September 2020 Tablets & Capsules on the right is a surface coated and processed using CN+, a proprietary method that modifies the coating surface to reduce formulation sticking to the punch face. The peak- to-valley height is the same on the CN surface as it is on the CN+ surface. However, when looking at the peak-to- peak value, the surface textures differ dramatically. To eliminate sticking, manufacturers must analyze the effect of the interaction between the granule and the sur- face finish. There are several methods they can employ, including optical surface profilometry, which measures the surface roughness after polishing; scanning electron microscopy, which studies the structure of the steels and the coatings; and, as previously mentioned, AFM, which measures adhesion forces and can be used to create a nanoscale map of the surface. Table 1 shows the results of a case study that tested different coatings on compression tooling used to tablet ibuprofen. The tooling was placed in a tablet press with 39 stations and run at three different speeds with a main compression force of 17 kilonewtons and a pre-com- pression force unchanged throughout the test. Five tool- ing samples were tested, including coated and uncoated stainless-steel tooling manufactured by a competitor and three PharmaCote-treated tooling samples. The competitor's stainless-steel and coated tooling created severe sticking issues while the CN+ and ECxtra (E-Chrome) samples presented only partial sticking. The CT-textured chromium-nitrate coating, which does not have a mirror finish and would once not have been used due to its Ra value, resolved all the sticking issues during ibuprofen tableting. No single solution Sticking is detrimental to tablet production and costly, as it inevitably results in downtime and reduced produc- tivity. To mass produce quality tablets, you must first resolve any sticking issues. Because the physical proper- ties of each sticky formulation are unique, there is no one-size-fits-all, anti-stick solution. Applying a predictive tool such as TSAR that analyzes several sticking causes and suggests a suitable punch or die coating solution can save time and money compared to slow and costly on- or off-site compression trials. T&C References 1. V. Waknis et. al., "Molecular basis of crystal mor- phology-dependent adhesion behavior of mefenamic acid during tableting," Pharm Res. 2014;31(1):160-172. 2. J. Wang et. al., "Modeling of adhesion in tablet compression--I. Atomic force microscopy and molecular simulation," J Pharm Sci. 2003;92(4):798-814. Rob Blanchard is research development & quality systems manager at I Holland (www.tablettingscience.com, +44 115 972 6153). I Holland manufactures steel tooling and the PharmaCote line of tool coating. faces can include a range of surfaces that interact with formulations in different ways. The required standard surface for a punch tip is between 0.1 to 0.025 roughness average (Ra). Figure 5 shows two different surfaces within the Ra parameters. On the left is a surface coated with PharmaCote CN and Table 1 Tool coating case study Process Parameters Tablet press: XP500 Stations: 39 Press speeds: 40 rpm/50 rpm/60 rpm Main compression: 17kN max Sample Results Competitor uncoated stainless steel Sticking present Competitor coated stainless steel Sticking present CN+ Partial sticking ECxtra Partial sticking CT No sticking Figure 5 Comparison of CN and CN+ coating surfaces (Both meet EuroStandard, TSM, and ISO 18084 surface finish specifications of 0.1 to 0.025 Ra) 365 μm 365 μm 365 μm 365 μm