Effect of Hydrophobic Powders on the Tensile Strength of the Tablet

Zoe Chu1,2, Christopher Windows-Yule¹, Ian Gabbott², Gavin Reynolds², Rachael Shinebaum² and Andy Ingram¹1. School of Chemical Engineering, University of Birmingham, Edgbaston, B15 2TT2. Oral Product Development, Pharmaceutical Technology & Development, Operations, AstraZeneca, Macclesfield, UKEmail: zhc906@student.bham.ac.ukIntroductionA tablet consists of the active pharmaceutical ingredients (API), and the other components, excipients. A tablet needs to withstand coating, packing and shipping stresses whilst maintaining the dissolution time; therefore, the tensile strength is of great importance. Currently, there is a lack of understanding on why excipients improve the bulk powder properties and the bonding mechanisms of the powder during compression. This makes tablet formulation development an inefficient trial-and-error process that is required for every new API (1). Literature has shown that the surface energy of the powders contributes a significant amount towards the tablet tensile strength. Hydrophobic powders have a lower surface energy (2) and are seen to disrupt this tablet strength (3,4).Experimental Aim and MethodThe aim was to investigate the impact of the hydrophobicity of excipient powders on tabletability of microcrystalline cellulose. This was done by mixing powders of varying hydrophobicity with MCC at varying mass fractions. There was focus on a lower mass fraction (0.02-0.1 m/m) with increasing increments of 0.02 m/m of added additive as well as gaining a global picture (0.2-1 m/m) with increments of 0.2 m/m.ResultsIt was found that at low mass fractions (0.02-0.4 m/m) of additive added the hydrophobic powders disrupted the tablet strength more compared to hydrophilic powders which could be attributed to the levels of surface energy of the additive. In contrast, at higher mass fractions (0.6-0.8 m/m), the surface energy is not as important and it is hypothesised that the deformation mechanisms of the additives governs the tablet strength.1. Reynolds GK, Campbell JI, Roberts RJ. A compressibility based model for predicting the tensile strength of directly compressed pharmaceutical powder mixtures. Int J Pharm [Internet]. 2017;531(1):215–24. Available from: http://dx.doi.org/10.1016/j.ijpharm.2017.08.0752. Sunkara D, Capece M. Influence of Material Properties on the Effectiveness of Glidants Used to Improve the Flowability of Cohesive Pharmaceutical Powders. AAPS PharmSciTech. 2018;19(4):1920–30. 3. Zuurman K, Maarschalk KVDV, Bolhuis GK. Effect of magnesium stearate on bonding and porosity expansion of tablets produced from materials with different consolidation properties. 1999;179:107–15. 4. Mishra SM, Rohera BD. Mechanics of tablet formation: a comparative evaluation of percolation theory with classical concepts. Pharm Dev Technol [Internet]. 2019;24(8):954–66. Available from: https://doi.org/10.1080/10837450.2019.1599913