Characterization and evaluation of novel hydrogels based on new dendritic polymers as antimicrobial carrier systems.

GARCÍA, MC.; CUGGINO, J.; ROSSET, C.; ALOVERO, F.; MANZO, RH.; ALVAREZ IGARZABAL, C.; JIMENEZ KAIRUZ, AF.

Porto Gallinas

Simposio; XIV Latin American Symposium on Polymers, SLAP 2014.; 2014

Asociación Brasileira de Polímeros

1 INTRODUCTION Hydrogels are three-dimensional, cross-linked networks of water soluble polymers. A particular class of hydrogels is based on drug-polyelectrolite (D-PE) complexes constituted by a molecular dispersion of D ionically bounded at the ionizable pending groups of PE , , , . The unique physical properties of these hydrogels place them as interesting systems to be used en controlled D delivery . Recently, a new anionic dendritic polylelectrolyte (DP) was synthesized, by aqueous free-radical polymerization, from a vinyl monomer derivative of Behera´s amine . This work is aimed to the characterization and evaluation of DP-Ciprofloxacin (CIP) complexes, as hidrogels, with potential use in topical and/or mucosal opportunist infections treatment. CIP was selected as ionizable model drug because of its wide use in common topical opportunist infections. 2 MATERIALS AND METHODS A series of DPx, where ?x? is the DP crosslinking degree were obtained by the addition of 0.5, 2 and 4 mol% (+)-N, N'-diallyltartramide. They were used to obtain DP-CIP complexes by ionic reaction in solid state in which free base CIP neutralized 25% of the acid groups of DP. The mixture of DP and CIP was mixing with appropriate volume of ethanol to obtain a semisolid paste of DPx-CIP25. The complexes were kept at room temperature for 24 h and dried until constant weight at 40 °C. The solid complexes were characterized by spectroscopic, calorimetric, crystallographic and rheological techniques (FTIR, DSC/TG, DRXP, optical microscopy and oscillatory rheology). To obtain the hydrogels, the complexes DPx-CIP25 were dispersed in distilled water with an appropriate amount of 1M NaOH which neutralized 20% of the acid groups of DP. In vitro release studies in diffusion Franz cells from DPx-CIP25-Na20 hydrogel were performed where the receptor compartment was filled with water, 0.9% NaCl, pH 6.8 USP-buffer solution. Antimicrobial activity and physicochemical properties of interest for topical application were evaluated. Cytotoxicity was determined by assay of DP direct contact with a monolayer of fibroblast cells from skin according to ISO 10993-5 . The antimicrobial potency of DP2-CIP25-Na20 bioassay was performed using the technique of cylinder-plate diffusion, free CIP being used as reference. Skin irritation potentials from hydrogels with and without CIP, DP2-Na20 and DP2-CIP25-Na20, were evaluated in rabbits using the Draize score test. On day 0 of the test period, backs were clipped free of hair. Several layers of skin were removed with adhesive tape from one half of the shaved back and areas of skin abrasion were created. Each rabbit was treated with 0.5 ml of the DP2-Na20 and DP2-CIP25-Na20 hygrogels, which were applied over a 6.25 cm2 area of hair-free skin. This test was performed according to guidelines established by Resolution 288/90 from Ministry of Health of Argentine and Standard ISO , . 3 RESULTS AND DISCUSSION The FT-IR, DXRP, DSC and optical microscopy analysis showed ionic interaction between DP and CIP in DPx-CIP25 complexes. Opaque, viscous and stable DPx-CIP25-Na20 hydrogels were obtained, which the range of pH resulting was 6.2 to 6.8. Viscoelastic measurement showed predominant storage moduli, that was increased with the DP crosslinking degree. Hydrogels exhibited a slow release of CIP towards water, while is raised significantly (3 to 5 times) promoting by ionic exchange when water was replaced by NaCl solution. An intermediate behavior was observed when buffer solution was in the receptor compartment. Release profiles has a good fitted with Peppas equation and not significant differences were observed among the different cross-linking grades (p>0.05). Citotoxicity assays proved the no-toxicity of DP. Hydrogel of ionic complex DP2-CIP25-Na20 inhibited bacterial growth, suggesting a reversible PE-CIP interaction. However, DP2-CIP25-Na20 exhibits a potency equivalent to 38 and 58% of that exhibited by similar concentrations of CIP solution against S. aureus and P. aeruginosa, respectively. On the other hand, no inhibitory effect was shown by the drug-free polymer. Absence of edema and erythema was observed, which indicate high biocompatibility of the hydrogels. Thus DP would be classified as non-irritant. 4 CONCLUSIONS New controlled release systems based on DP-CIP were developed. The DPx-CIP25-Na20 hydrogels are physically stable, biocompatible and behaves as a reservoir of CIP. In addition, they showed acceptable microbiological activity. These systems showed promising properties that could be exploited for topical and mucosal opportunist infections treatment.