title: Macroindentation hardness measurement-Modernization and applications.
abstract: In this study, we first developed a modernized indentation technique for measuring tablet hardness. This technique is featured by rapid digital image capture, using a calibrated light microscope, and precise area-determination. We then systematically studied effects of key experimental parameters, including indentation force, speed, and holding time, on measured hardness of a very soft material, hydroxypropyl cellulose, and a very hard material, dibasic calcium phosphate, to cover a wide range of material properties. Based on the results, a holding period of 3min at the peak indentation load is recommended to minimize the effect of testing speed on H. Using this method, we show that an exponential decay function well describes the relationship between tablet hardness and porosity for seven commonly used pharmaceutical powders investigated in this work. We propose that H and H at zero porosity may be used to quantify the tablet deformability and powder plasticity, respectively.
authors.affiliation: Pharmaceutical Materials Science and Engineering Laboratory, Department of Pharmaceutics, College of Pharmacy, University of Minnesota, Minneapolis, MN, USA.
authors.forename: Sarsvat
authors.initials: S
authors.lastname: Patel
authors.affiliation: Pharmaceutical Materials Science and Engineering Laboratory, Department of Pharmaceutics, College of Pharmacy, University of Minnesota, Minneapolis, MN, USA. Electronic address: sunx0053@umn.edu.
authors.forename: Changquan Calvin
authors.initials: CC
authors.lastname: Sun
mesh_terms: D002130:Calcium Phosphates / Q000737:chemistry*; D002482:Cellulose / Q000031:analogs & derivatives* / Q000737:chemistry; D002626:Chemistry, Pharmaceutical / Q000379:methods*; D004339:Drug Compounding / Q000379:methods; D005079:Excipients / Q000737:chemistry*; D006244:Hardness; D016062:Porosity; D011208:Powders; D013607:Tablets; D013678:Technology, Pharmaceutical / Q000379:methods
chemical_list: D002130:Calcium Phosphates; D005079:Excipients; D011208:Powders; D013607:Tablets; D002482:Cellulose; C008079:hydroxypropylcellulose; C485829:calcium phosphate, dibasic, anhydrous
keywords: Indentation; Plasticity; Powder technology; Tableting