In vitro Evaluation of Solutions Prepared From Mucoadhesive Polymers

Abstract

Abstract: : Purpose: Ocular mucoadhesive systems involve dosage forms containing polymers which are able to adhere to the mucins present on the ocular surface. Topical treatments of ocular surface disorders include the use of mucoadhesive polymers, being the ocular surface exposed to these agents for a long time. The aim of this work was to evaluate in–vitro mucoadhesion of hypotonic and isotonic solutions containing hyaluronic acid (sodium salt) (HA–Na) and polyacrlylic acids (PAA) of different molecular weights. Methods: Hypotonic and isotonic solutions of Hyaluronic acid sodium salt (HA–Na Mw1,3x 10⁶ Da) and polyacrylic acids (Mw 450,000 and 1,25 x 10⁶ Da) were prepared at concentrations: 0.1; 0.2 and 0.3 % (w/v). Isotonicity was adjusted with ClNa (HA–Na) or Mannitol (PAA). The vehicle employed was an aqueous solution of phosphate buffer pH (6,0) being used as reference (AS). Mucoadhesion measurements were carried out using a tensiometer. The adhesion values obtained for the formulations (n=5) were expressed as a percentaje of mucin–mucin standard measurements (100% mucoadhesion). Cell viability assays were performed by the MTT method based on cellular mitochondrial respiration. Results: High molecular weight PAA rendered the higher mucoadhesion values (133.21% ± 4.89). HA–Na (0.1%) presented a similar value of mucin–mucin adhesion (106.6% ± 10) while the formulation without polymer addition (AS) resulted in less mucoadhesiveness (87.27%± 3.5). Cell viability was decreased for PAA formulations depending on the molecular weight of polymer and its concentration. Only treatment with PAA (1,25 x 10⁶Da) solution resulted in a significant decrease of cellular respiration. No significant differences were observed between isotonic and hypotonic solutions. Conclusions: In vitro mucoadhesion properties allow characterizing bioadhesive polymers. Taking into account that formulations containing mucoadhesive polymers are widely employed to hydrate the ocular surface, further studies are necessary to evaluate their effects on long– term treatments.

Keywords: cornea: tears/tear film/dry eye