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The linear range was 3.9-52.9 mg/L. The imprecision was less than 12%, the limits of detection and quantification were less than 0.13 and 0.72 mg/L, respectively. The sample carry-over and ion suppression were insignificant. In the standard dose group, the median teicoplanin concentrations were 7.5 mg/L (days 3-5) and 8.9 mg/L (on days 6-8) and the proportion of trough levels achieving ≥10 mg/L, was 20% (days 3-5) and 38% (days 6-8), respectively. In the TDM-guided individualized dose group, median teicoplanin concentration was higher (16.9 mg/L), and the proportion of trough levels ≥10 mg/L was also higher (77%) when compared with the standard dose group CONCLUSIONS:: Based on these results, the present UHPLC-MS/MS method can be considered suitable for routine TDM of teicoplanin. Also based on the insufficient trough teicoplanin concentrations achieved with standard dose regimen, and the higher trough teicoplanin concentrations achieved with TDM-guided individualized dose regimen, this study highlights the importance of TDM of teicoplanin, especially in high-risk patient groups.

Abstract Background A pilot external quality assurance (EQA) survey for the free light chain (FLC) assay was developed and implemented in Korea. Methods Survey data over 6 years (2010–2015) were collected retrospectively and Sigma metrics were calculated for method-specific peer groups. Results Nineteen to 29 laboratories participated in the EQA survey, and nephelometric (20%) and turbidimetric (80%) methods were used. Using a previously published clinically relevant reference change value (RCV) of 54.5% as the tolerance limit, the method-specific median Sigma metrics of kappa (κ) and lambda (λ) FLC achieved greater than Three-Sigma for 86–97% of all EQA distributions, and Five-Sigma for 48–72% of all distributions. Conclusions This EQA analysis of FLC assay applied clinically relevant quality specifications using Sigma metrics. During the 6-year EQA survey, we found that most of the results from participating laboratories meet clinically relevant quality specifications. In addition, method-specific differences were noted for λ FLC, at FLC concentrations above the initial measuring range that require a sample dilution.

Summary Background Posaconazole (PCZ) is a triazole approved for prophylaxis of invasive fungal infections. Objectives Herein, the impact of clinical variables on PCZ plasma concentrations (PPCs) attained with PCZ delayed‐release tablet (DRT) was investigated and compared with a historical cohort treated with PCZ oral suspension (OS). Patients/Methods Steady‐state PCZ PPCs in 513 patients with haematologic malignancy treated with PCZ‐DRT were assessed and impact of variables were analysed. Also, a comparison with matched historical cohort treated with PCZ‐OS was made. Results The median PPC in the PCZ‐DRT group was 1,308.9 ng/mL (range: 29.8‐10 455.9). Use of proton pump inhibitor (1181 vs 1344 ng/mL, P = .0337) in the AML/myelodysplastic syndrome remission induction group, diarrhoea (867 vs 1543 ng/mL, P = .0325) and gastrointestinal graft‐versus‐host disease (870 vs 1713 ng/mL, P = .0178) in the HSCT group were associated with lower PPCs. There was lack of evidence that hepatotoxicity was related with PCZ‐DRT. Higher prevalence of UGT1A4*3 allele (33.0%) was noted compared to allele frequency in Koreans in those with PPCs < 500 mg/mL. The median PPC in the PCZ‐DRT group was significantly higher than that in the PCZ‐OS group (1308.9 vs 713.0 ng/mL, P < .0001). Significantly less patients had PPCs < 700 ng/mL in the PCZ‐DRT group compared to the PCZ‐OS group (18.7% vs 48.0%, P < .0001). Conclusions Our study demonstrates that PCZ‐DRT has enhanced absorption and bioavailability than PCZ‐OS in real‐world clinical settings. In addition, specific factors associated with lower PPCs should prompt consideration of therapeutic drug monitoring in patients treated with PCZ‐DRT.

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