Polysaccharide-based membranes loaded with erythromycin for application as wound dressings

In this study, the antibiotic erythromycin (Ery) was incorporated into chitosan (Ch)-alginate (A) and Ch-xanthan (X) membranes with the aim of using them as bioactive wound dressings. Drug incorporation was performed by direct addition (DA) to the polysaccharide mixture and by membrane impregnation in solution (IS). A higher incorporation efficiency was obtained for DA, but higher amounts of drug were loaded into membranes by the IS method (maxima approximate to 2.1 and 0.7 g/g for Ch-X and Ch-A, respectively) because the initial concentration of drug could be higher than that in the DA method. Ery release in phosphate-buffered saline was slow, reaching about 12 and 32 mg of drug/g of membrane in 60 h for Ch-X and 4 and 16 mg/g for Ch-A by the DA and IS methods, respectively. With formulations prepared with IS, the required therapeutic dosage was reached within 60 h, whereas for those incorporating the drug by DA, prolonged use would be required. Both membrane types behaved as drug reservoirs, providing continuous antibiotic release to the wound site. Formulations with higher drug contents showed effective antibacterial activity against two species of bacteria commonly found in skin lesions, Staphylococcus aureus and Pseudomonas aeruginosa, and were thus potentially capable of protecting the wound site from bacterial attack. (C) 2016 Wiley Periodicals, Inc.