Development and Evaluation of a Thermosensitive In Situ Gel Formulation for Intravaginal Delivery of Lactobacillus gasseri

In situ administration of vaginal probiotics has been proposed as an effective prevention strategy against gynecological diseases caused by microecological disorders. In this study, a thermosensitive in situ gel formulation was prepared for intravaginal delivery of Lactobacillus gasseri (L. gasseri). The optimized formulation was characterized for the rheological properties, in vitro release properties, and microencapsulation efficiency. The mixtures of poloxamer 407 (26.0% w/w) and 188 (9.0% w/w) produced an increase in gelation extent at 37 °C after dilution in simulated vaginal fluid (SVF). The presence of a low concentration of hyaluronic acid (HA, 0.3% w/w) improved the mucoadhesive properties and the capability to gel at 37 °C. Additionally, the viability of L. gasseri encapsulated with alginate or via co-extrusion technique with fructooligosaccharide (FOS, 0.5% w/w) was maintained at 11 log CFU/mL for eight weeks at 4 °C. In conclusion, the evaluation of the in situ thermosensitive gel formulation was shown to be efficacious for intravaginal delivery of L. gasseri with suitable textural and rheological properties.