A novel double-layer mucoadhesive tablet containing probiotic strain for vaginal administration: Design, development and technological evaluation.

Vulvovaginal candidosis caused by Candida spp. is the most prevalent vaginal infection in Europe and the second one in EE.UU, so it has become a major female concern. Probiotics bacteria have been proposed as an alternative treatment with the aim of avoiding the adverse effects associated with conventional therapies including antibiotics and other aggressive drugs for the vaginal mucosa and microbiota. The purpose of this work was to design and develop a novel vaginal tablet that contained Lactobacillus spp. bacteria as a treatment against vulvovaginal infections. A total of 21 two-layers vaginal tablets, which contained different polymeric ratios, were proposed. However, formulation F4 (20mg Na-CMC; 50mg Carbopol® 934; 20mg chitosan) was selected as optimal according to its swelling index and dissolution/erosion capability. F4 tablets showed suitable technological properties for vaginal administration as well as mucoadhesion time (24.36±0.88h) and force (0.0941N). Disintegration assay in simulated vaginal fluid (SVF, pH5.5) showed that effervescent layer disappeared in 27.48±0.05s whilst matrix layer was totally gelled in 1h. Two different release profiles were achieved; on the one hand, a promptly release due to the dissolution of both effervescent layer and matrix layer's surface (1.10×108CFU/g), on the second hand, a prolonged released of the remaining bacteria until 24h (5.48×107CFU/g). For stability and storage study, it was found that bacteria viability was constant until 90days in both ways of storage, in a desiccator and at room temperature, with a final dosage of 108CFU/g which was considered appropriate for vaginal therapy (108-1010CFU/g).