Silica sol-gel for the controlled release of antibiotics. I. Synthesis, characterization, and in vitro release

Room temperature processed silica sol-gel (xerogel) was investigated as a n ovel controlled release carrier of antibiotics (vancomycin). Xerogel charac teristics, in vitro release properties, and bactericidal efficacy of the re leased antibiotic were determined. The xerogel/vancomycin composite showed a long-term sustained release (up to 6 weeks). In addition, bactericidal ef ficacy of released vancomycin was retained. The kinetics of release and the amount released were dose dependent. The initial, first-order release was followed by a near-zero-order release. The time to transition from the firs t- to zero-order release increased with vancomycin load (from 2 to 3 weeks with load increase from 2.2 to 11.1 mg/g). Regardless of the load, about 70 % of the original vancomycin content was released by the transitional point , and the cumulative release after 6 weeks of immersion was about 90%. This study, combined with other reports documenting biocompatibility and contro lled resorbability of the xerogel/drug, composite in vivo, suggests that si lica xerogel is a promising controlled release material for the treatment o f bone infections. (C) 2001 John Wiley & Sons, Inc.