Comparative In Vitro Release Study of Vitamin C from Spirulina-Based Matrix Tablets: Influence of Excipients on Dissolution Kinetics and Tablet Performance.

Objective (s): This study aimed to compare the in vitro release kinetics of vitamin C from spirulina-based matrix tablets and to evaluate the influence of selected excipients on dissolution behavior and tablet performance. Design: Four formulations were prepared by varying the proportions of vitamin C, spirulina, HPMC, starch, microcrystalline cellulose, and lactose. Tablets were manufactured by direct compression and evaluated according to pharmacopeial standards. Intervention (s): Dissolution testing was performed in 0.1 N HCl (pH 1.2) at 37 °C for 4 hours. Vitamin C quantification was carried out by HPLC DAD at 245 nm. Main outcome measure(s): Dissolution profiles, mechanical properties, and similarity/difference factors (f₂, f₁). Results: Spirulina significantly improved tablet hardness, while starch and microcrystalline cellulose accelerated vitamin C release. HPMC produced a sustained release matrix, whereas lactose exerted a neutral to slightly inhibitory effect. Spirulina containing tablets showed prolonged release but also partial vitamin C oxidation after 90 minutes, likely due to transition metal ions naturally present in spirulina. Dissolution comparison revealed non similarity between formulations (e.g., F2 vs F4: f₁ = 17.2; F3 vs F4: f₂ = 42.75). Conclusion: Excipient composition strongly modulates both mechanical strength and release kinetics of vitamin C matrix tablets. Spirulina enhances hardness and sustains release but may promote oxidative degradation. Optimizing excipient ratios is essential for achieving robust and stable nutraceutical formulations. In vivo studies are recommended.