Silica sol-gel for the controlled release of antibiotics. II. The effect of synthesis parameters on the in vitro release kinetics of vancomycin

Room temperature-processed silica sol-gel (xerogel) was investigated as a n ovel controlled release carrier of vancomycin for the treatment of osteomye litis. Vancomycin-loaded xerogels were fabricated with varying water/ alkox ysilane molar ratios and vancomycin concentrations. The goal of this study was to determine the effect of varying the aforementioned synthesis paramet ers on the daily in vitro release kinetics of vancomycin from the xerogel d isks. A controlled, load-dependent, long-term release of vancomycin was obs erved for all of the molar ratios that were used in the study (4, 6, and 10 ). Variations in the water/ alkoxysilane molar ratio affected the release p rocess extensively. A cumulative release of about 90% of the original amoun t of vancomycin was found for molar ratios 6 and 10 by 21 and 14 days, resp ectively. Only about 30% was released from xerogels with a molar ratio of 4 after 21 days of immersion. A first-order release stage was followed by a steady release stage for xerogels with molar ratios of 6 and 10, whereas ze ro-order release was observed for xerogels with a molar ratio of 4. The fin dings of this study indicate that the release kinetics of vancomycin from x erogel can be tailored by varying the xerogel synthesis parameters. (C) 200 1 John Wiley & Sons, Inc.