Background Joint prosthesis infection is a growing public health problem. The infections occur during surgery or in the postoperative period, and more rarely through blood. According to the time of onset and clinical settings (Tsukayama classification), 60% of infections are caused by staphylococcus spp. Vancomycin is one of the antibiotics commonly used. Therapeutic drug monitoring (TDM) of vancomycin is recommended because of its narrow therapeutic range.
Purpose To assess the impact of implementation of a new dosage schedule for vancomycin on plasma concentrations of this antibiotic and on renal function in patients with first time replacement prosthesis.
Material and methods Retrospective cohort study from December 2013 to May 2015 performed in a 400 bed tertiary university hospital. Patients undergoing first time replacement prosthesis were included. Vancomycin dosage schedule: first day 1 g/8 h; second day 1 g/12 h and blood samples for TDM.
Data collected: demographics, weight, treatment duration, vancomycin Cmin and AUC, recommended dose to achieve Cmin 20–25 µg/mL, initial and final renal function (serum creatinine (Scr), ClCr Cockroft-Gault) and nephrotoxicity defined by the RIFLE Scale for renal failure.
Pharmacokinetic analysis: Bayesian estimation compartmental model (PKS System Abbott).
Data are shown as median (Q1-Q3). Statistical analysis was performed using non-parametric tests.
Results Patients included: 84 (42 male), 69.5 (57.2–78.0) years, 79.0 (68.5–94.0) kg.
Treatment duration: 9 (7–13) days. Cmin 10.8 (6.3–15.9) µg/mL. AUC 463 (348–585) µg.h/ml. Increasing dose 71 (84.5%) patients, decreasing 8 (9.5%). Recommended dose 3 (2.4–4) g/day.
Renal function: Scr initial 0.70 (0.56–0.87) mg/dL, Scr final 0.74 (0.60–0.88) mg/dL. ClCrCockroft-Gault initial 105 (72–147) ml/min, final 106 (77–148) mL/min. RIFLE 1–2––0-0. Nephrotoxicity 3.6%.
Conclusion Although an increase in initial vancomycin dose was implemented, most patients did not achieve therapeutic trough levels. This situation may be explained by high ClCr values in the patients included. However, AUC values agreed with optimal pharmacokinetic concentrations against microorganisms, with MIC <1 µg/mL.
The new dosage schedule of vancomycin showed insufficient maintenance doses of this antibiotic on the second day of treatment. Vancomycin nephrotoxicity was negligible.
No conflict of interest.
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