Analysis of vancomycin therapeutic drug monitoring in two multidisciplinary hospitals in Latvia, with and without a monitoring protocol

Vancomycin is a glycopeptide antibiotic which acts against various gram-positive microorganisms. Systemic infections are treated with intravenous vancomycin with dosing adapted to renal function and body weight. Due to the narrow therapeutic index, therapeutic drug monitoring should be performed. That helps to reach adequate therapeutic efficacy, while reducing the risk of potential nephrotoxicity. However, even various guidelines for appropriate vancomycin therapy is available, majority of patients do not reach appropriate vancomycin concentration. Inadequate therapeutic drug monitoring is often mentioned as a reason. Therefore, various approaches are implemented for more precise monitoring of vancomycin concentration, including supervision of clinical pharmacist.Retrospective study was performed in two multidisciplinary hospitals in Latvia. The aim of the study was to investigate details of monitoring of vancomycin concentration, to investigate influence of therapeutic drug monitoring protocol developed by clinical pharmacist. Data about the patients included in the study  were analyzed based on gender, age, body weight, BMI, renal function. Data about vancomycin therapy analyzed: dosing schemes (vancomycin dose and dosing interval), data about loading and maintenance doses, vancomycin concentration, details about vancomycin concentration (sampling time and concentration level). Differences between the hospitals were found in terms of documenting the initiation of vancomycin administration and concentration sampling- more correct notes were found in hospital with protocol if compared with the hospital without the protocol (97.22% vs. 18.95%, p<0.001), performance of administration of loading dose (22.73% vs. 1.29%, p<0.01) and reaching target concentration (55.56% vs. 35.29%, p<0.01). Concentration sampling in correct timeframe before the vancomycin dose and vancomycin administration did not show statistically better results in either of hospitals (4.60% vs.6.29%, p=0.786). Better results were in the hospital with TDM protocol. However, for long term maintenance of good results and improvement of vancomycin administration regular training for medical professionals is necessary.