Gels Containing Poloxamer 407 and Sodium Alginate as Vehicles for Vaginal Administration

Sodium alginate and poloxamer 407 were both studied in order to design a hydrogel-based delivery system as a platform for the formulation of vaginal medecines. Sodium alginate is a natural anionic mucoadhesive polymer while poloxamer 407 is a temperature-sensitive polymer. A commercial alginate was characterized. Then, its solutions (0.5-2 % w/w), poloxamer 407 solutions (16-21.5 % w/w) and their mixtures were prepared. Their rheological properties and the influence of vaginal simulated fluid were assessed. This commercial alginate had a mannuronate-to-guluronate ratio of 1.24, a weight-average molecular weight of 300 000 ± 2% g.mol-1, a polydispersity index of 1.8 ± 3%. Alginate solutions displayed a viscous behavior not suitable for a vaginal administration. Poloxamer solutions and their mixtures with alginate were temperature-sensitive, shear-thinning, non-thixotropic and had an elastic behavior suitable for a vaginal administration. Their resistance to dilution with vaginal fluid could prolonge vaginal residence. Keywords: Formulation, poloxamer 407, rheology, sodium alginate, temperature–sensitive, vaginal fluid, viscoelastic properties.