Comparison of In Vitro Dissolution Profiles of Vancomycin and Cement Mechanical Strength among Vancomycin-laden : Bone Cements Containing Various Commercial Vancomycin Products

Bone cements have been widely used to fill the dead space of bone tissues in orthopaedic surgeries.Loaded with antibiotics,these materials are also administered for the prevention and treatment of infections,infectious osteomyelitis for example.We made polymethylmethacrylate cement preparations of five commercial vancomycin (VCM) products and compared the in vitro dissolution profiles of the VCM in them and mechanical strengths of the cements.When immersed in phosphate buffer (PB) for 30 days,dissolved amounts of VCM ranged between just 5 and 19% of the calculated contents and after immersion in PB for 40 days mechanical strengths were significantly decreased (50-75% of the control without VCM).Further,on testing a cement preparation containing pharmaceutical additives as well as VCM,the amount of antibiotic released was significantly larger than that for other preparations and the release was more rapid as well.This cement preparation also had the lowest strength among those studied.By doing this,we showed that pharmaceutical additives could have marked effect on the dissolution of the antibiotic and mechanical strength for antibiotic-laden bone cements for the first time,though these were in vitro findings.The present study clearly demonstrated that the antibiotic products used can cause functional differences in antibioticladen bone cements and also suggested that pharmaceutical additives influence cement functions.It is therefore necessary to pay attention to both the antibiotic content of commercial VCM products and types of pharmaceutical additive in the preparation of such cements.