Simplex lattice design for the development of arrowroot starch and sodium alginate with calcium chloride crosslinker as a capsule shell alternative.

Gelatin, commonly used for capsule shells, is mostly imported from Europe and America to Indonesia. However, Indonesia's rich biodiversity offers abundant natural alternatives like arrowroot and alginate. The need for local raw material independence in pharmaceuticals drives this research. This study aims to determine whether arrowroot starch and sodium alginate with calcium chloride as a crosslinker can replace gelatin capsule shells. This study involved five capsule shell formulas (F1-F5), with evaluations on characteristics, swelling %, disintegration time, dispersive X-ray, Fourier-transform infrared (FTIR) analysis, and simplex lattice design (SLD) method optimization, using commercial capsules (CCs) as a control. We used the one-sample t-test. F3 showed the best results in weight uniformity (0.22 ± 0.01 g), %swelling (45.84 ± 0.08%), and disintegration time (8.22 ± 0.85 min), compared to the CC, i.e., weight uniformity (0.12 ± 0.003 g), %swelling (43.26 ± 0.03%), and disintegration time (6.19 ± 1.38 min). Morphologically, F3 was the most homogeneous, resembling CC. FTIR analysis showed hydroxyl band from carboxylic group shifts indicating crosslinking, with notable changes from 1416.6 to 1386.9/cm in F3 and 1417.7-1394.0/cm in F5 after CaCl₂ addition. SLD validation was performed on three model-generated equations using experimental data. The differences between predicted and experimental results were 34.54% (weight uniformity), 3.12% (swelling), and 5.35% (disintegration time). A one-sample t-test showed no significant differences (α > 0.05). Arrowroot starch and sodium alginate with calcium chloride crosslinker can be used as an alternative to capsule shells.