In vitro elution of antibiotic from antibiotic-impregnated biodegradable calcium alginate wound dressing

Objective: The authors investigated the calcium alginate dressing as a drug -delivery system fur the treatment of various surgical infections. Methods: Cytotoxicity of the calcium alginate dressing to fibroblasts and H eLa cells was evaluated by the 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H tetrazolium bromide (MTT) colorimetric assay. The calcium alginate dressin g was mixed with vancomycin, and lyophilized or not lyophilized to form two types of antibiotic dressings, The antibiotic dressings were placed in 2 m t of phosphate buffered saline (PBS) or in PBS containing 0.01% Calcium ion s, and incubated at 37 degrees C. The PBS was changed daily, and the remove d solutions were stored at -70 degrees C until the antibiotic concentration in each sample was determined by high performance liquid chromatography as say. Results: The results suggested that the antibiotic dressings present no obv ious toxic risk to their use as a drug-delivery system. The concentration o f vancomycin in each sample was well above the breakpoint sensitivity conce ntration (the antibiotic concentration at the transition point between bact erial killing and resistance to the antibiotic) for more than 14 days. The release was most marked during the first 48 hours. The concentration of cal cium ions in PBS and the lyophilization of the manufacture process of antib iotic dressings prolonged the antibiotic diffusion duration. The diameter o f the sample inhibition zone ranged from 10 to 11 mm, and the relative acti vity of vancomycin ranged from 62.88% to 92.18%. Conclusion: All antibiotic dressings released bactericidal concentrations o f the antibiotics in vitro for the period of time needed to treat surgical infections, This study offers a convenient method to meet the specific anti biotic requirement for different patients.