The impacts of roller compaction on the quality attributes of simultaneously compressed micro and minitablets

The challenges of developing good quality low dose minitablets was assessed by systematically studying the effects of ibuprofen (IBU, a model compound) particle sizes (6-58 µm D₅₀) and concentrations (0.1-3 %w/w), roller compaction forces (3-7 kN/cm), and the minitablet sizes (1.2, 1.5 and 2 mm diameter). A novel compression approach, where all three minitablet sizes were simultaneously produced in a single compression run was used. Roller compacted ribbons, granules, minitablets were characterized for physico-mechanical properties and minitablets were also characterized for stratified content uniformity and weight uniformity. The results showed that roll force was the more dominant factor to ribbon solid fraction or tensile strength and granule size enlargement. Minitablets obtained from the granules had good weight uniformity; all but one batch met the <Ph. Eur. 2.9.5 > criteria. The precise control of tooling lengths across the various sizes was found profoundly important for achieving expected weights, solid fraction, and tensile strength of the simultaneously produced minitablets. The roller compaction process considerably improved the CU variability of the minitablets as compared to the direct compression process. Smaller particle size and higher concentration of IBU, increased roller compaction force, and larger minitablet size improved the potency and content uniformity; however, only the minitablet size was a statistically significant factor in this study. As a product strategic design criterion, a threshold of 25 minitablets in a dosage unit would ensure robust downstream filling and weight verification operations as well as dose accuracy and uniformity (would pass <USP 905> stage 1 criteria). This study results demonstrated feasibility of the novel simultaneous compression approach and the roller compaction process in developing good quality minitablets.