Innovation of Rice Straw Cellulose-Based Tablet Excipients Through Isolation, Characterization, and Performance Evaluation Stages

The demand for high-quality cellulose-based pharmaceutical excipients continues to increase, while their availability still largely depends on commercial materials and imported products. Rice straw, an agricultural waste rich in cellulose, has the potential to be developed as an economical and sustainable alternative source of tablet excipients. This study aimed to isolate cellulose from rice straw, characterize its physicochemical properties, and evaluate its performance as a tablet excipient. The study was conducted using an experimental approach through preparation, delignification using 4% NaOH, and bleaching using 5% H₂O₂. The isolated cellulose was characterized using Fourier Transform Infrared (FT-IR), X-Ray Diffraction (XRD), and Scanning Electron Microscopy (SEM), as well as evaluated for its flowability and compressibility properties. Subsequently, the isolated cellulose was formulated as a tablet excipient and evaluated based on tablet weight uniformity and hardness. The results showed that 289 g of dried cellulose was obtained from 1,000 g of rice straw, with a final yield of 28.9%. FT-IR analysis confirmed the presence of characteristic cellulose functional groups, including O–H stretching (3,300–3,400 cm⁻¹), C–H stretching (approximately 2,900 cm⁻¹), C–O vibration (1,050–1,060 cm⁻¹), and β-1,4-glycosidic bonds (approximately 900 cm⁻¹). XRD analysis revealed a cellulose type I structure with a Crystallinity Index (CI) of 62.6%, while SEM analysis showed short fiber and irregular flake-like morphologies. The isolated cellulose exhibited good flowability and compressibility properties, with an angle of repose of 34.72 ± 0.86°, Carr index of 21.95 ± 0.74%, and Hausner ratio of 1.28 ± 0.01. The formulated tablets showed an average weight of 500.4 ± 3.2 mg and hardness of 6.21 ± 0.42 kgf (60.9 ± 4.1 N). These findings indicate that rice straw-derived cellulose has potential as a natural-based tablet excipient.