Preclinical Potential of Probiotic-Loaded Novel Gelatin-Oil Vaginal Suppositories: Efficacy, Stability, and Safety Studies

The current study describes a suppository base composed of aqueous gelatin solution emulsifying oil globules with probiotic cells dispersed within. The favorable mechanical properties of gelatin to provide a solid gelled structure, and the tendency of its proteins to unravel into long strings that interlace when cooled, lead to a three-dimensional structure that can trap a lot of liquid, which was exploited herein to result in a promising suppository form. The latter maintained incorporated probiotic spores of Bacillus coagulans Unique IS-2 in a viable but non-germinating form, preventing spoilage during storage and imparting protection against the growth of any other contaminating organism (self-preserved formulation). The gelatin-oil-probiotic suppository showed uniformity in weight and probiotic content (23 ± 2.481 × 10⁸ cfu) with favorable swelling (double) followed by erosion and complete dissolution within 6 h of administration, leading to the release of probiotic (within 45 min) from the matrix into simulated vaginal fluid. Microscopic images indicated presence of probiotics and oil globules enmeshed in the gelatin network. High viability (24.3 ± 0.46 × 10⁸), germination upon application and a self-preserving nature were attributed to the optimum water activity (0.593 a_w) of the developed composition. The retention of suppositories, germination of probiotics and their in vivo efficacy and safety in vulvovaginal candidiasis murine model are also reported.