The vaginal sheet: an innovative form of vaginal film for the treatment of vaginal infections.

Objective: To develop and characterize a new form of vaginal film.Significance: This formulation is intended to overcome some known limitations of traditional dosage forms. It has an absorptive intention to control symptoms and to improve the treatment of vaginal infections characterized by excessive fluid. The vaginal sheet is a thick drug delivery system easy to manipulate, nontoxic and composed by biocompatible macromolecules and polymers, such as gelatin and chitosan.Methods: The sheets were prepared by formulating gelatin or chitosan based gels isolated or in combination, in association with a plasticizer. Gels were subsequently lyophilized. Different proportions of polymer:plasticizer were tested. Lactose was used as a surrogate to study powder incorporation in the formulation. All formulations were analyzed regarding their organoleptic characteristics, texture (hardness and resilience), in vitro absorption efficiency of vaginal fluid simulant - VFS (pH 4 and 5), pH and acid-buffering capacity.Results: Different properties were obtained by varying polymer and plasticizer proportions. Combinations including gelatin with propylene glycol showed the best organoleptic characteristics. The best proportions were 4:3 and 4:5. Up to 10% of powder was successfully incorporated in the formulation. Hardness and resilience of formulations were largely dependent on the concentration of plasticizer. Absorption of vaginal fluid was found to be highly efficient, especially at pH 5. Buffering capacity, upon dilution in normal saline and VFS, was generally higher for VFS pH 4.Conclusions: The vaginal sheet is a promising solid drug delivery system able to further incorporate drugs to treat vaginal clinical conditions characterized by excessive fluid.

Optimization and Application of In Vitro and Ex Vivo Models for Vaginal Semisolids Safety Evaluation.

Preclinical safety assessment of vaginal products includes cytotoxicity assays upon cell lines. Furthermore, tissue explants have been considered for application on ex vivo models. In this study, traditional and renewed methods were studied for toxicity assessment of vaginal semisolids upon products currently used in clinical practice as antimicrobials (Gino-Canesten®, Sertopic®, Dermofix®, Gyno-Pevaryl®, Lomexin®, Gino Travogen®, Dalacin V®), containing estrogens (Ovestin®, Blissel®, Colpotrophine®), and reference formulations (Replens®, Universal Placebo). Two in vitro cytotoxicity tests were performed: 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and neutral red uptake upon uterine (HEC-1A), cervical (HeLa) and vaginal (VK2 E6/E7) cells, according to ISO/EN 10993-5 (in vitro evaluation of medical devices). Similarly, a strategy to determine tissue viability on ex vivo porcine vaginal model (through MTT reduction assay and histological analysis) was developed and optimized. The vaginal cell line VK2 E6/E7 conducted to the most accurate calculation of half-maximal toxic concentration among all cells on the MTT assay. However, it was shown not be sensitive to the neutral red uptake assay. Tissues from the porcine model were collected with approx. 15% variability in thickness and variation coefficients lower than 25% when testing negative and positive controls were achieved. These models can improve cost-efficiency in early steps of product development.

Vaginal semisolid products: Technological performance considering physiologic parameters.

Vaginal semisolid products are frequently used to treat vaginal infections and atrophy-related symptoms of menopause. Formulations composition and the methods for their characterization, especially those developed concerning the target epithelia, are key tools to predict in vivo results at early stages of product development. However, recent studies on this subject have been almost exclusively focused on anti-HIV preparations. The aim of this work consists on improving traditional characterization methods by using physiological parameters in order to construct predictive tools to characterize a new ideal vaginal semisolid formulation whatever target it may have. Ten vaginal antimicrobial and hormonal products already available in the market were studied (Gino-Canesten®, Sertopic®, Dermofix®, Gyno-pevaryl®, Lomexin®, Gino Travogen®, Dalacin V®, Ovestin®, Blissel®, Colpotrophine®). Furthermore, Universal Placebo gel and Replens® were used for comparison. Products were characterized in terms of: pH and buffering capacity in a vaginal fluid simulant (VFS); osmolality - directly and upon dilution in VFS; textural parameters (firmness, adhesiveness and bioadhesion) using vaginal ex vivo porcine epithelium; and viscosity (including VFS dilution at 37°C and after administration on an ex vivo model). Interestingly, the majority of the tested commercial vaginal formulations did not present technological characteristics close to the ideal ones when tested under target biological conditions. The inclusion of such methodologic adaptations is expected to optimize cost-efficiency of new formulations development by predicting efficacy and safety profiles at early stages of product development.

Studies and methodologies on vaginal drug permeation.

The vagina stands as an important alternative to the oral route for those systemic drugs that are poorly absorbed orally or are rapidly metabolized by the liver. Drug permeation through the vaginal tissue can be estimated by using in vitro, ex vivo and in vivo models. The latter ones, although more realistic, assume ethical and biological limitations due to animal handling. Therefore, in vitro and ex vivo models have been developed to predict drug absorption through the vagina while allowing for simultaneous toxicity and pathogenesis studies. This review focuses on available methodologies to study vaginal drug permeation discussing their advantages and drawbacks. The technical complexity, costs and the ethical issues of an available model, along with its accuracy and reproducibility will determine if it is valid and applicable. Therefore every model shall be evaluated, validated and standardized in order to allow for extrapolations and results presumption, and so improving vaginal drug research and stressing its benefits.