Ca-alginate beads loaded with meloxicam: effect of alginate chemical composition on the properties of the beads and ulcerogenicity of the drug

Ca-alginate beads loaded with meloxicam (MX) were produced by dripping dispersion of MX in sodium alginate solution into gently stirred CaCl2 solution. Alginates having different mannuronic-block to guluronic-block (MM/GG) ratios were utilized in bead preparation. The gelation of the beads continued for a long time and was dependent on the MM/GG ratio as well as the alginate fraction. Swelling and erosion of Ca-alginate beads were observed in phosphate buffer (pH 7.4). MX release in 0.1 N HCl was scarce while, in phosphate buffer (pH 7.4), the release was dependent on MM/GG ratio and drug content. With the increase in MM block fraction, the MX release increased. The release was consistent with the swelling of the beads and alginate release from the beads (erosion). Scanning electron microscopy (SEM) photographs showed that the prepared beads were nearly spherical in shape and small (about 1 mm diameter). The surface of the beads showed cracks and fissures. Differential scanning calorimetry (DSC) indicated that MX was present in the beads in crystalline form. The gastric mucosa of the rat administered free MX showed complete disappearance of mucosal surface with marked ulceration. On administration of the beads loaded with MX, no ulceration or even inflammation was observed. In conclusion, alginate beads loaded with MX gave different patterns of release according to MM/GG ratio and MX:Alg ratio. Taking into account that MX is NSAIDs, variation in release pattern is important and could be used to protect the GIT from its side effects.