Influence of cerebral fluid drainage on the pharmacokinetics of vancomycin in neurosurgical patients.

The objective of this study was to retrospectively investigate the influence of cerebral fluid drainage on the serum concentrations and pharmacokinetic parameters of vancomycin (VCM). We analyzed 55 patients with normal renal function who had been hospitalized in the neurosurgical ward and received intravenous infusions of VCM. We compared the daily doses of VCM, serum VCM concentrations, serum concentration/dose ratio (C/D ratio), and pharmacokinetic parameters calculated using the Sawchuk-Zaske method between patients who underwent cerebral fluid drainage (drainage group) and controls (non-drainage group). The patients in the drainage group showed a significantly lower trough concentration of VCM (5.8 ± 3.3 μg/mL) than that shown by the non-drainage group (9.9 ± 5.4 μg/mL, p = 0.017). Further, the patients in the drainage group showed a significantly lower trough C/D ratio (0.32 ± 0.17) than that shown by the non-drainage group (0.50 ± 0.31, p = 0.047). In conclusion, cerebral fluid drainage may influence VCM pharmacokinetics. Our findings strongly suggest that a high dose of VCM is required to maintain optimal serum concentrations of VCM in patients managed with cerebral fluid drainage.