Dose Escalation Trial of Intrasite Vancomycin Pharmacokinetics

Surgical wound infections remain a serious problem despite aseptic techniques and the use of prophylactic systemic antibiotics. Such infections can occur at rates up to \~20% in high-risk patients receiving long segment instrumented spinal fusions for deformity correction and present potentially catastrophic consequences. Given this, the high cost of treatment, and a payer system unable to support such expenses, investigators must make every effort to find new cost-effective ways to prevent these complications. Increasingly surgeons have sought to address this problem by placing lyophilized Vancomycin into spinal surgery wounds immediately prior to wound closure. This method, known as "intrasite" application, is adapted from techniques used to prevent infection in joint replacement surgeries. The motivation for this practice is to maximize antibiotic concentration within the wound while minimizing systemic concentration and toxicity, (the inverse of the situation when using IV antibiotics). While the popularity of intrasite delivery has grown rapidly, this has occurred without prospective scientific evidence. Recently, three retrospective papers including nearly 2,500 treated patients, indicated that intrasite Vancomycin reduces wound infections without increasing adverse events\[1-3\]. However, there are no published data on the dosing or pharmacokinetics of intrasite Vancomycin, let alone prospective trials of its efficacy and safety. The investigators propose to perform the first prospective trial of intrasite Vancomycin pharmacokinetics and safety. Study objectives will include standardizing application and dosing, defining peak/trough concentrations and clearance parameters, verifying bactericidal potency, and dose selection for use in future studies. This will be accomplished by enrolling groups of patients (n=10) to receive one of three doses of intrasite lyophilized Vancomycin (3, 6 or 12 mg/cm2), prior to wound closure. Vancomycin concentrations in venous blood and wound seroma fluid will be measured at regular intervals after surgery to establish pharmacokinetic parameters. Preliminary data regarding local and systemic adverse events including wound healing, fusion rate, and toxicity will be prospectively collected. The ultimate goal of this learning-phase study is to gather sufficient information regarding application, dosing, pharmacokinetics, measurement strategies, and adverse events to prepare for a Phase III efficacy trial.