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Compressibility In another study, researchers exam- ined the compressibility of a dry gran- ulation [3]. The resulting granules were used to make tablets that were then compared to tablets made with either FCC in powder form, calcium carbonate, mannitol, or microcrys- talline cellulose (MCC). The researchers then compared the tensile strength and porosity of tablets made across a range of compression pressures (figures 2a and 2b). At low compression pressure, the tensile strength of tablets formulated with FCC powder or granules was higher than that of tablets formulated with mannitol or calcium carbonate and was comparable to that of tablets for- mulated with MCC. Across the range of compression pressures applied, the FCC tablets had a higher porosity than the tablets made using the other excipients tested. The authors also tested tablets formulated with parac- etamol (figures 2c and 2d). The authors concluded that the tensile strength and porosity relationships between tablets formulated with differ- ent excipients did not change signifi- cantly after paracetamol was incorpo- rated. In addition, FCC could be granu- lated both by high-shear mixing and dry granulation, although the high- shear method would require optimiz- ing because the FCC's lamellae were partially damaged by the 150-rpm impeller and 1,500-rpm chopper that the researchers used. Regardless, with FCC in the formulation, tablets could reach comparable or higher hardness than other formulations at lower com- Figure 2 Compression and porosity of tablets made using FCC and reference excipients with and without API [2] b. Porosity versus mean compression pressure for tablets formulated with one of the following: 1) FCC powder, 2) FCC granules by roller compaction, 3) FCC granules by high- shear mixing, 4) calcium carbonate, 5) mannitol, or 6) MCC. The starting porosity of FCC tablets is higher than tablets formulated with the reference excipients. As compression pressure increases, the porosity of the FCC tablets decreases significantly less than that of tablets formulated with the reference excipients. a. Tensile strength versus mean compression pressure for tablets formulated with one of the following: 1) FCC powder, 2) FCC granules by roller compaction, 3) FCC granules by high-shear mixing, 4) calcium carbonate, 5) mannitol, or 6) MCC. At lower compression pressures, FCC tablets reach tensile strengths higher than or comparable to tablets formulated with other reference excipients. FCC powder FCC granules by roller compaction FCC granules by high-shear mixing Calcium carbonate Mannitol MCC FCC powder FCC granules by roller compaction FCC granules by high-shear mixing Mannitol MCC Calcium carbonate 0 200 400 600 Mean compression pressure (MPa) Porosity (%) 0 200 400 600 Mean compression pressure (MPa) 100 80 60 40 20 0 15 10 5 0 d. Porosity versus mean compression pressure of tablets for- mulated with paracetamol and one of the following: FCC powder or MCC. Despite the presence of an API, as com- pression pressures increase, the porosity of the FCC tablets decreases significantly less than that of tablets formulated with MCC. c. Tensile strength versus mean compression pressure for tablets formulated with paracetamol and one of the following: FCC powder or MCC. Tensile strength of FCC tablets was comparable to that of tablets formulated with MCC. FCC powder 50% FCC powder and 50% paracetamol MCC 50% MCC and 50% paracetamol 100% Paracetamol FCC powder 50% FCC powder and 50% paracetamol MCC 50% MCC and 50% paracetamol 100% Paracetamol 0 200 400 600 Mean compression pressure (MPa) Porosity (%) Tensile strength (MPa) 0 200 400 600 Mean compression pressure (MPa) 15 10 5 0 100 80 60 40 20 0 46 September 2015 Tablets & Capsules