Physicochemical and release properties of anthocyanin gastric floating tablets colloidized with κ-carrageenan/metal ions

Gastro-retentive carriers have recently been used to improve the quality of biologically active components and their controlled-release. Anthocyanins are biologically active compounds that are absorbed and digested in the stomach. In this study, κ-carrageenan, sodium bicarbonate, calcium carbonate, and potassium chloride were used to produce anthocyanin gastric floating tablets (GFTs). The GFTs had a hardness of 6.63–8.58 kgf and friability of 0.02–0.05%. Differential scanning calorimetry and X-ray diffraction revealed a good excipient stability. Metal ions changed the κ-carrageenan type and concentration, which influenced composite hydrogel film production and anthocyanin release. An increase in potassium ions increased –OH stretching (3600–3000 cm−1) and calcium ions improved hydrogel properties, lowering the tablet swelling ratio from 80.48 to 66.67%, thereby facilitating the formation of a stable κ-carrageenan gel structure. This also increased the duration of anthocyanin release in the simulated gastric fluids from 180 to 300 min. GFTs can be used as gastro-retentive carriers for the delivery of pharmaceuticals and functional supplements.