Formulation of mucoadhesive vaginal hydrogels insensitive to dilution with vaginal fluids

The main objective of this work was to design thermosensitive and mucoadhesive vaginal hydrogels able to keep their rheological and mucoadhesive properties after dilution with vaginal fluids. Formulations were composed of pluronic F127 or a mix of two pluronics F127 and F68. Both formulations contained hydroxypropylmethyl cellulose (HPMC) as a mucoadhesive polymer. The determination of gelling temperature (T(gel)) after dilution with simulated vaginal fluid (SVF) demonstrated that hydrogels were resistant to dilution and T(gel) values were close to 30°C. Ex vivo mucoadhesion experiments conducted on porcine vaginal mucosa founded on the technique of traction of the adhesive/adherent joint allowed the characterization of mucoadhesive properties of hydrogels by measuring work of adhesion (W) and maximum force of detachment (F(max)). In the case of F127-based hydrogels, W and F(max) were lowered after dilution with SVF. However, in the case of F127/F68-based hydrogels, W, F(max) and mucoadhesion profiles were weakly affected by dilution. These differences could be attributed to the higher elasticity of F127/F68/HPMC (22.5/2.5/1% w/w) hydrogel in comparison with F127/HPMC one (20/1% w/w). Indeed, rheological analyses of the formulations showed that both elastic (G') and viscous moduli (G'') were higher for F127/F68/HPMC (22.5/2.5/1% w/w) than for F127/HPMC hydrogel (20/1% w/w). However, we demonstrated that the higher elasticity of the hydrogel was due to the higher total pluronic concentration and not due to the presence of F68 in the formulation.