DOS 2018

198 · DOS Abstracts Vancomycin concentrations in the cervical spine after intravenous administration – results from an experimental porcine study Mats Bue, Pelle Hanberg, Mikkel Tøttrup, Maja B Thomassen, Hanne Birke- Sørensen, Theis M Thillemann, Torben L Andersson, Kjeld Søballe Department of Orthopaedic Surgery, Horsens Regional Hospital; Department of Orthopaedic Surgery, Randers Regional Hospital; Orthopaedic Resarch Unit, Aarhus University Hospital; Department of Orthopaedic Surgery, Aarhus University Hospital; Department of Clinical Biochemistry, Aarhus University Hospital Background: Vancomycin may be an important drug for intravenous periopera- tive antimicrobial prophylaxis in spine surgery. Purpose / Aim of Study: The present study aimed to assess single-dose van- comycin pharmacokinetics in the intervertebral disc, the vertebral cancellous bone, and subcutaneous adipose tissue using microdialysis in a porcine model. Materials and Methods: Eight female pigs received 1,000 mg of vancomy- cin intravenously as a single dose over 100 minutes. Microdialysis probes were placed in the C3-C4 intervertebral disc, C3 vertebral cancellous bone, and sub- cutaneous adipose tissue, and vancomycin concentrations were obtained over 8 hours. Venous blood samples were obtained as reference. Findings / Results: Ranging from 0.24 to 0.60, vancomycin tissue penetra- tion was incomplete for all compartments. The lowest penetration was found in the intervertebral disc. The time to a mean clinically relevant minimal inhibitory concentration (MIC) of 4 μg/mL were 3, 17, 25, and 156 min for plasma, sub- cutaneous adipose tissue, vertebral cancellous bone and the intervertebral disc, respectively. In contrast to the other compartments, a mean MIC of 8 μg/mL was not reached in the intervertebral disc. An approximately three-times longer elimination rate was observed in the intervertebral disc in comparison to all the other compartments (p < 0.001), and the time to peak drug concentration was higher for all tissues compared with plasma. Conclusions: Preoperative administration of 1,000 mg of vancomycin may provide adequate vancomycin tissue concentrations with a considerable delay, though tissue penetration was incomplete. However, in order also to achieve adequate intervertebral disc concentrations in all individuals and accommodat- ing a potentially higher MIC target, supplemental application of vancomycin may be necessary. 139.