Pharmacist-managed dose adjustment feedback using therapeutic drug monitoring of vancomycin was useful for patients with methicillin-resistant Staphylococcus aureus infections: a single institution experience

Background: Vancomycin (VCM) requires dose adjustment based on therapeutic drug monitoring. At Aomori Prefectural Central Hospital, physicians carried out VCM therapeutic drug monitoring based on their experience, because pharmacists did not participate in the dose adjustment. We evaluated the impact of an Antimicrobial Stewardship Program (ASP) on attaining target VCM trough concentrations and pharmacokinetics (PK)/pharmacodynamics (PD) parameters in patients with methicillin-resistant Staphylococcus aureus (MRSA) infections. Materials and methods: The ASP was introduced in April 2012. We implemented a prospective audit of prescribed VCM dosages and provided feedback based on measured VCM trough concentrations. In a retrospective pre- and postcomparison study from April 2007 to December 2011 (preimplementation) and from April 2012 to December 2014 (postimplementation), 79 patients were treated for MRSA infection with VCM, and trough concentrations were monitored (pre, n=28; post, n=51). In 65 patients (pre, n=15; post, n=50), 24-hour area under the concentration-time curve (AUC 0-24 h)/minimum inhibitory concentration (MIC) ratios were calculated. Results: Pharmacist feedback, which included recommendations for changing dose or using alternative anti-MRSA antibiotics, was highly accepted during postimplementation (88%, 29/33). The number of patients with serum VCM concentrations within the therapeutic range (10-20 mg/mL) was significantly higher during postimplementation (84%, 43/51) than during preimplementation (39%, 11/28) (P<0.01). The percentage of patients who attained target PK/PD parameters (AUC 0-24 h/MIC >400) was significantly higher during postimplementation (84%, 42/50) than during preimplementation (53%, 8/15; P=0.013). There were no significant differences in nephrotoxicity or mortality rate. Conclusion: Our ASP increased the percentage of patients that attained optimal VCM trough concentrations and PK/PD parameters, which contributed to the appropriate use of VCM in patients with MRSA infections.