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Sang-Mi Kim,1 Hyun-Seung Lee,1 Na-Young Hwang,2 Kyunga Kim,2 Hyung-Doo Park,1 Soo-Youn Lee1,3,4 1Department of Laboratory Medicine and Genetics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea; 2Statistics and Data Center, Research Institute for Future Medicine, Samsung Medical Center, Seoul, Korea; 3Department of Clinical Pharmacology & Therapeutics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea; 4Department of Health Science and Technology, Samsung Advanced Institute of Health Science and Technology, Sungkyunkwan University, Seoul, KoreaCorrespondence: Soo-Youn LeeDepartment of Laboratory Medicine and Genetics, Samsung Medical Center, Sungkyunkwan University School of Medicine, 81 Ilwon-ro, Gangnam-gu, Seoul, 06351, KoreaTel +82-2-3410-1834Fax +82-2-3410-2719Email suddenbz@skku.eduBackground: To date, outcome data with a large sample size and data regarding the clinical outcomes of pharmacokinetic-guided (PK) dosing of vancomycin are limited.Aim: We evaluated the pharmacokinetic and clinical outcomes of a PK-guided dosing advisory program, pharmacokinetic consultation service (PKCS), in vancomycin treatment.Methods: We investigated vancomycin therapeutic drug monitoring (TDM) and PKCS use through a retrospective review of patients who had serum vancomycin trough concentration data from October 2017 to November 2018. Among these patients, we selected non-critically ill adult patients satisfying our selection criteria to evaluate the effect of PKCS. Target trough attainment rate, time to target attainment, vancomycin-induced nephrotoxicity (VIN), vancomycin treatment failure rate, and duration of vancomycin therapy were compared between patients whose dosing was adjusted according to PKCS (PKCS group), and those whose dose was adjusted at the discretion of the attending physician (non-PKCS group).Results: A total of 280 patients met the selection criteria for the VIN analysis (PKCS, n=134; non-PKCS, n=146). The incidence of VIN was similar between the two groups (PKCS, n=5; non-PKCS, n=5); however, the target attainment rate was higher in the PKCS group (75% vs 60%, P = 0.012). The time to target attainment was similar between the two groups. Further exclusions yielded 112 patients for the clinical outcome evaluation (PKCS, n=51; non-PKCS, n=61). The treatment failure rate was similar, and the duration of vancomycin therapy was longer in the PKCS group (12 vs 8 days, P = 0.008).Conclusion: In non-critically ill patients, an increase in target trough achieved by PKCS did not lead to decreased vancomycin treatment failures, shorter vancomycin treatment, or decreased nephrotoxicity in vancomycin treatment. Considering the excessive amount of effort currently put into vancomycin dosing and monitoring, more selective criteria for individualized pharmacokinetic-guided dosing needs to be applied.Keywords: vancomycin, pharmacokinetics, dosing, therapeutic drug monitoring, trough concentration, nephrotoxicity

Rihwa Choi,1,2 Hye In Woo,1 Hyung-Doo Park,1 Soo-Youn Lee1,31Department of Laboratory Medicine and Genetics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea; 2Department of Laboratory Medicine, Green Cross Laboratories, Yongin, Gyeonggi, Republic of Korea; 3Department of Clinical Pharmacology and Therapeutics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of KoreaPurpose: The current status of therapeutic drug monitoring (TDM) assay utilization by clinical laboratories in South Korea remains little known. We investigated the TDM status of five antibiotics known for nephrotoxicity (vancomycin, amikacin, gentamicin, tobramycin, and teicoplanin) for the improvement of TDM in South Korea among patients with infectious diseases using a cross-sectional nationwide survey.Patients and methods: We developed an online questionnaire and collected responses using a user-friendly web-based platform. The survey included questions about laboratory characteristics, implementation and operation of drug assays, implementation and operation of TDM consulting services, patient needs, and barriers to providing better TDM service including expectations and concerns about other platform-based drug assays.Results: Among a total of 235 clinical laboratories, 112 (47.7%) responded, and 62 of the responding laboratories (55.4%) possessed drug assay facilities. Only 41.2% to 58.1% of respondents were providing TDM consulting services for each antibiotic. Respondents indicated that there are unmet needs regarding drug assays and TDM consultation as well as barriers to TDM utilization including high operating costs, lack of knowledge about TDM, lack of user-friendly software, lack of medical and laboratory information systems that can access patient information critical for TDM dose calculation, and reimbursement issues.Conclusion: This study, the first nationwide survey addressing these questions, showed that there are barriers against the utilization of TDM in South Korea. These barriers may be addressed by improving drug assays and TDM consulting services with the goals of new analytical method development, better interpretation of results, consultation services, and quality control.Keywords: questionnaire, TDM service, TDM consulting, point-of-care