Gelatin Films Modified with Acidic and Polyelectrolyte Polymers—Material Selection for Soft Gastroresistant Capsules

Abstract

The following investigation comprised the formation of acid-resistant gelatin-based films, intended for future use in soft-capsule technology. Such film compositions were obtained by including nonionized forms of acid-insoluble polymers in a gelatin-based film-forming mixture. The selected films were additionally modified with small amounts of anionic polysaccharides that have potential to interact with gelatin, forming polyelectrolyte complexes. The obtained film compositions were subjected to, e.g., disintegration tests, adhesiveness tests, differential scanning calorimetry (DSC), and a transparency study. As a result of the performed study, some commercial enteric polymers (acrylates), as well as cellulose acetate phthalate, were selected as components that have the ability to coalesce and form a continuous phase within a gelatin film. The use of a small amount (1.5%) of additional gelling polymers improved the rheological characteristics and adhesive properties of the obtained films, with ί-carrageenan and gellan gum appearing to be the most beneficial.

Prototype Gastro-Resistant Soft Gelatin Films and Capsules—Imaging and Performance In Vitro

“…Macroscopically it was visible that the samples after the acid treatment became opaque and swollen. Under the microscope, the untreated samples had a smooth surface with no structures visible [6]. As presented in Figure 3, the films after submersion in acid revealed a network-like structures, resembling scaffolds.…”

“…A very important issue associated with the development of a new capsule shell composition is to identify the physiochemical phenomena that can be utilized in designing and manufacturing of modified release gelatin-based films. In our previous work, selection of the most effective modification of the shell material composition was performed, and their microstructure and barrier properties were described [5,6]. However, there are still a few unexplained issues in the description of the phenomena that lead to formation of the films, as well as the changes that the films undergo when exposed to various conditions.…”

“…The preparation method of the film-forming mixtures and films was described in detail in the 91 previously published work [5,6]. Shortly, the mixture of components (…”

“…After closing the form, the resulting 99 reservoirs were filled with: (a) MCT oil, (b) PEG 400 or (c) cetearyl alcohol. For a better visual The preparation method of the film-forming mixtures and films was described in detail in the previously published work [5,6]. Shortly, the mixture of components (Table 1) was stirred at 80 • C for 2 h, which was followed by deaeration under vacuum.…”

“…The film selected for the test was gelatin + Aquacoat + carrageenan (GAC), the same as for structures visible [6]. As presented in Figure 3, the films after submersion in acid revealed a network-169 like structures, resembling scaffolds.…”