Adsorption and release of antibiotics from morselized cancellous bone in vitro studies of 8 antibiotics

Abstract

We studied the basic release patterns of antibiotics from cancellous bone in vitro. Antibiotic-impregnated bone was compressed into a wire-mesh cylinder and the release of antibiotic was assessed by two different in vitro methods: agar diffusion and broth elution. The zones of inhibition were measured on seeded agar and the amounts of antibiotics released in elution tubes were assessed by a bioassay. The study continued for 21 days with daily transfer of the cylinders. The results indicated that benzylpenicillin, dicloxacillin, cephalotin, netilmicin, clindamycin, vancomycin, ciprofloxacin and rifampicin were adsorbed to cancellous bone in vitro. Compared to broth elution, agar diffusion showed a prolonged period of release, owing to the small amounts of antibiotic leaking out of the cylinder into the agar. The betalactams had antibacterial activity in broth for a shorter time than the other antibiotics. The release patterns of the betalactams were similar, in spite of their differences in thermal stability. Only rifampicin showed a concentration higher than MIC for longer than 21 days.

Alendronate enhances antibiotic-impregnated bone grafts in the treatment of osteomyelitis

“…Beta-lactams have been shown to lose their antibacterial effect after a few days [22]. The pH of the impregnation fluid affects the amount of antibiotics released.…”

“…The above-mentioned studies on drug impregnation into bone grafts were done with commercially available human dry cancellous bone chips [22][23][24]. In order for us to comply with these studies we preferred to use commercially available bone grafts during our study.…”

“…Various biomaterials have been tried for local delivery of adequate antibiotic dose to the infection site [4,7,15]. Bone grafts have also been used as antibiotic carriers with favourable outcomes [5][6][7]22].…”

Incorporation of vancomycin-supplemented bone allograftsRadiographical, histopathological and immunohistochemical study in pigs

“…The use of cancellous bone to act as a carrier for vancomycin has been reported in vitro and in vivo (McLaren 1989, Witso et al 1999, Winkler et al 2000. Initially, the concentrations of antibiotics in the surrounding medium are high; they then fall to lower levels which persist for long periods.…”

“…Recent experiments with cancellous bone as a delivery vehicle for vancomycin in vitro and in vivo have shown high initial peak concentrations of antibiotics in the surrounding medium, followed by low levels for long periods (Witso et al 1999, Winkler et al 2000. However, high concentrations of vancomycin can substantially reduce osteoblast replication and even cause cell death , Edin et al 1996.…”