Mechanical characteristics of orally disintegrating films: Comparison of folding endurance and tensile properties.

The tensile test is the most widely used method for testing the mechanical characteristics of orally disintegrating films (ODFs). The other available test is the folding endurance (FE) test, which is more suitable for clarifying the actual strength during the manufacturing and dosing. However, the FE test is performed manually, and the FE number it generates has not been adequately analyzed as an index. The aim of this studies were to establish an automatic method for determining the FE number, and to compare the resulting FE numbers with the tensile properties. For this purpose, a desktop-model endurance test machine was used. First, the operating conditions-i.e., the folding angle, the folding speed and the weight requirement were optimized using ODF models. Secondly, the FE of ODFs prepared from three film formers (HPMC, HPC, and PVA) and with insoluble particles (calcium carbonate), plasticizers (glycerin) and APIs (acetaminophen), was evaluated and compared with the tensile properties. Lastly, the commercial ODFs were investigated. The results showed that our automatic system could be successfully used to determine the FE characteristics of ODFs. FE was suggested to relate to not only the strength but also the elongation during the tensile test.