Issue link: https://www.e-digitaleditions.com/i/1371139
Tablets & Capsules May/June 2021 29 the material have been reached. This often coincides with no further increase in TFS with increasing compaction pressure, another warning sign of problems. A note on material true density values: The material true density value of the sample is the one piece of information needed prior to analysis to generate a full compaction tri- angle data set. For most excipients and well-studied APIs, this value can be easily found in a suitable reference. It is an additive value, so the true density of a blend can be calculated from the true density values of its individ- ual components. In a case where the material true density value is simply not available, compaction analysis can still provide useful information because the tabletability profile (often the most useful piece of data) is independent of the material true density value. A lubrication assessment can also be carried out without the true density value. Compactibility A compactibility plot shows how the tablet tensile fracture stress changes with solid fraction. Generally, tablet tensile strength increases exponentially with solid fraction, as the presence of fewer or smaller pores strengthens a compact. If two samples display similar solid fractions but differing tablet tensile strength values, then the difference in strength is caused by differences in the binding forces in the tablet. Very high densities due to over compaction result in slower dissolution and increased risk of capping. In the example compactibility profile in Figure 2c, the data show that tablets of similar solid fraction from each formulation have significantly different strengths. This implies that the differences in tablet strength between the formulations are not due to differing levels of porosity but rather to something more fundamental about the parti- cle interactions in the tablet. These differences are most likely the result of a change in excipient concentration or a major change in the manufacturing process, such as changing from granulation to direct compression, which usually reduces product performance. Elastic recovery For most formulations, the tablet dimensions change after the lower punch ejects the tablet from the die. Occasionally, the tablet contracts, but typically it expands. This dimensional change is termed elastic recovery. Elastic recovery is measured as the percent- age difference between the tablet volume at the time of ejection (the in-die tablet volume) and the tablet volume after ejection (the out-of-die tablet volume). High elas- tic recovery values have been linked to capping problems in production, but the relationship is complex, and the measurement is not a definitive indicator of capping. If capping is a problem with a formulation, looking at the elastic recovery and the solid fraction values (compress- ibility profile) is recommended. % Elastic recovery = In-die tablet volume Out-of-die tablet volume This filter is just one of over 100,000 replacement filters and parts Donaldson has in-stock and ready to ship today. Not tomorrow. Today. Find this filter and thousands more at shop.donaldson.com P190817-016-436 Ultra-Web ® fine fiber technology delivers longer filter life, cleaner air and greater cost savings. A proprietary substrate plus a fine fiber layer reduces pressure drop and increases airflow leading to longer filter life. © 2021 Donaldson Company, Inc. Donaldson.com 800.365.1331