Evaluation of the Film-Forming Ability for Heparinoid Cream Formulations

We compared the film-forming ability of a heparinoid cream (HP-C) formulation, an oil-in-water-type emulsion used as a moisturizer, and found that the original HP-C (HP-C_O) formulation formed a thick and robust film that floated easily on an acrylic plate. It is suggested that the thickness and robustness of HP-C_O contributed to the retention of its high keratin water content, while its floatability helped prevent adhesion to clothing after application. Among the generic HP-C formulations tested, only one (HP-C_G1) formed a film with properties similar to those of HP-C_O. When the HP-C formulations were mixed with white petrolatum, the floatability of the resulting film was eliminated, and the film easily disintegrated upon physical stimulation with a spatula. These results suggest that mixing the HP-C formulations with other ointment bases, such as white petrolatum, is not appropriate from the standpoint of film formation. Because peaks corresponding to glycerin (GL) were clearly observed in the near-IR spectra of both HP-C_O and HP-C_G1 after 24 h at room temperature, we explored the addition of water-soluble polyhydric alcohols, such as GL and propylene glycol (PG), to generic HP-C formulations that did not initially demonstrate good film-forming properties. The state of the film and its floatability tended to improve when these generic HP-C formulations were mixed with GL or PG. Thus, these results indicate that the film-forming ability differed depending on the HP-C formulation. Furthermore, the results suggest that GL played a key role in the successful film formation observed in both HP-C_O and HP-C_G1.