Formulation Based on Liposomes and Bioadhesive Polymers for Dry Eye Treatment. Tolerance Studies

Abstract

Purpose: : Stabilisation of preocular tear film can be performed through the administration of formulations which constituents are similar to the ones present in the tear film. Treatments directed to replace a disturbed lipid layer through pharmaceutical nanosystems (liposomes) result of therapeutic benefits for dry eye patients.The aim of this study was to evaluate the tolerance of a new formulation of liposomes dispersed in hyaluronic acid.

Methods: : Liposomes were prepared according to the technique described by Benitez J.M. et al. Final concentration of liposomes in a hypotonic solution of hyaluronic acid was 10mg/mL. Tonicity of formulation was adjusted with trehalose. Tolerance of the formulations was evaluated "in vitro" (Human Inmortalized-Limbal Epithelial Cells; HCLE) and "in vivo". Cytotoxicity studies, based on MTT method, were carried out at short (15minutes) and long term (1 and 4 hours) exposures. Acute ocular tolerance was performed in 9 male New Zealand white rabbits, weighing 2-2.5 kg. All the "in vivo" experiments were conducted in compliance with the ARVO statements for the Use of Animals in Ophthalmology and Vision Research. Rabbits received 30 µL of liposomes every 30 minutes for 6 hours. Contralateral left eye was used as control (no treatment). Corneal and conjunctival signs (hyperemia and staining) were evaluated.

Results: : Size of liposomes was 421.33±6.13 nm. The formulation of liposomes dispersed in hyaluronic presented an osmolarity value of 188.5±0.4 mOsm/L and a surface tension of 48.1±0.3 mN/m. Cell viability resulted higher than 80 % at short and long exposures for liposomal formulation. Animals did not present discomfort after administration of the formulation. Alteration in clinical signs (conjunctiva, cornea and lids) was not observed.

Conclusions: : The developed formulation of liposomes and hyaluronic acid presents good properties in terms of "in vitro" and "in vivo" tolerance.

Keywords: ocular irritancy/toxicity testing • lipids