Impact of calcium addition on the characteristics of hyaluronic acid-based oral films for vitamin D supplementation

An orally disintegrating film (ODF) was developed using hyaluronic acid as a base material, along with incorporation of vitamin D and varying amounts of calcium citrate. Increasing calcium amount within ODF resulted in higher opacity of the film, and stiffer texture. Microscopic examination of calcium-added films revealed consistently rough surfaces and cross-sections with irregular roughness. The moisture content and water vapor permeability were found to be higher in calcium-added films than in control films, however there was no significance by calcium amount. The content analysis indicated a loss of 32.66–46.16% of vitamin D and 8.05–13.53% of calcium in a sheet of ODF, which could be attributed to the formation of new chemical bonds among HA, vitamin D and calcium based on the result of FT-IR. In this study, it was successfully developed an ODF containing both vitamin D and calcium. However, unlike vitamin D, which can be added in recommended quantities within a single ODF, the addition of the insoluble bulk mineral, calcium, is limited, indicating that addition of plasticizer or technologies may be required to achieve an adequate amount of calcium incorporation into the ODF. [Display omitted] •The hydrocolloid of hyaluronic acid (HA) can form an oral film without plasticizer under appropriate temperature and humidity conditions.•Under these experimental conditions, the loading amount of Vitamin D corresponded to sufficient intake, however, loading of calcium into film was found to be highly limited.•The calcium content influenced the characteristics of the film, and of new chemical bonds among the components was observed.