Therapeutic drug monitoring (TDM) of anti-tuberculosis (TB) drugs is beneficial for patients responding slowly to treatment and those with multidrug-resistant TB. We used ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) to develop a rapid method for simultaneously measuring the blood concentrations of nine second-line anti-TB drugs: streptomycin, kanamycin, clarithromycin, cycloserine, moxifloxacin, levofloxacin, para-aminosalicylic acid, prothionamide and linezolid. Serum samples were extracted with acidified methanol and neutralized with NaOH. A Waters Acquity HSS T3 column and gradients of ammonium formate and acetonitrile in 0.1% formic acid were used for UPLC separation. Drug concentrations were determined by multiple reaction monitoring in positive ion mode, and assay performance was evaluated. We applied this method to TDM, analysing random serum samples from 85 patients treated with second-line drugs. Sample preparation using acidified methanol extraction followed by neutralization yielded good recovery and ionization efficiency, with chromatographic separation achieved within 3 min per sample. Within-run and between-run precisions were 1.7%–7.5% and 1.7%–12.4%, respectively, at concentrations representing low and high levels for the nine drugs. Lower limits of detection and quantification were 0.025–0.5 and 0.25–5.0 μg/mL, respectively. Linearity was acceptable at five concentrations for each drug. No ion suppression was observed at the retention time for most compounds, except for streptomycin, kanamycin and cycloserine, which were eluted close to the void volume of the column. In a limited pilot study, all quantifiable human samples had values within the validated assay ranges. The performance of our MS/MS detection technique was generally acceptable. The method provided rapid, sensitive and reproducible quantification of nine second-line anti-TB drugs and should facilitate drug monitoring during treatment.

Ki Ho Hong , M.D., Gab Jung Kim , Ph.D., Kyoung Ho Roh , M.D., Heungsup Sung , M.D., Jaehyeon Lee , M.D., So Yeon Kim , M.D., Taek Soo Kim , M.D., Jae-Sun Park , Ph.D., Hee Jae Huh , M.D., Younhee Park , M.D., Jae-Seok Kim , M.D., Hyun Soo Kim , M.D., Moon-Woo Seong , M.D., Nam Hee Ryoo , M.D., Sang Hoon Song , M.D., Hyukmin Lee , M.D., Gye Cheol Kwon , M.D., and Cheon Kwon Yoo , Ph.D.. Ann Lab Med 2022;42:391-7. https://doi.org/10.3343/alm.2022.42.4.391

Moon SY, et al. Ann Lab Med. 2014 Jan;34(1):7-14. http://dx.doi.org/10.3343/alm.2014.34.1.7

Accurate, precise and reliable laboratory test results play a critical role in medical decision making. To satisfy the increasing needs in clinical laboratory tests, the analyzers have been advanced. In this study, authors aimed to evaluate the analytical performance of the Alinity i system (Abbott Laboratories, IL, USA) for diverse analytes measured by using immunoassay principle. Analytical performance of recently launched Alinity i system has been evaluated for 31 assays in aspects of precision, linearity and analytical measurement range, correlation with the Architect i2000sr system (Abbott Laboratories), carry-over, and reference interval validation in accordance with CLSI guidelines. The within-laboratory CVs of the analytes tested in the study ranged between 1.00 and 7.84%, which met vendor claimed value in precision. In linearity test, most assays satisfied acceptable linearity criteria, best-fit first order regression or polynomial regression with nonlinearity smaller than ±10%, compared with linear regression. The recovery of each analyte distributed from 90.1 to 109.7%. The coefficient of determination (R2) for each test was larger than 0.95 except for folate when compared to the results obtained from existing routine analyzer and statistically or clinically equivalent. The carry-over rates were acceptable, and reference intervals were validated. Through this study, acceptable analytical performance of novel Alinity i system has been verified. It is expected to readily replace existing instrument and to be an option for laboratories considering introduction of automated immunoassay analyzer.

Hee Jae Huh, M.D., Ki Ho Hong, M.D., Taek Soo Kim, M.D., Sang Hoon Song, M.D., Kyoung Ho Roh, M.D., Hyukmin Lee, M.D., Gye Cheol Kwon, M.D.. Ann Lab Med 2021;41:225-9. https://doi.org/10.3343/alm.2021.41.2.225

Point-of-care (POC) tests are used increasingly due to fast results and simple test procedures, which enables rapid diagnosis and therapeutic monitoring. We evaluated the performance of the Piccolo xpress Chemistry Analyzer (Abaxis, USA) a POC chemistry analyzer. Fourteen analytes, Na(+), K(+), Cl(-), Ca(2+), total carbon dioxide, AST, ALT, total bilirubin, alkaline phosphatase, blood urea nitrogen, creatinine, albumin, total protein, and glucose; were measured simultaneously with a 100 microL of whole blood sample using a Comprehensive Metabolic Reagent disk. Within-run and total precision and linearity were evaluated according to CLSI EP15-A and EP6-A guidelines, respectively. Comparison with a central laboratory chemistry analyzer was performed using 144 patient samples. The coefficients of variations of within-run and total precision were all within 5% for three levels except for total carbon dioxide, ALT, alkaline phosphatase, total bilirubin, and creatinine in low level, and creatinine in middle level. The results of 14 analytes were linear within a commonly encountered range in clinical samples (r(2)> or =0.98). More than 10% of samples in Na(+), AST, ALT, glucose, BUN did not satisfy CLIA analytical quality requirement. The Piccolo xpress Chemistry Analyzer can analyze multiple analytes with a minimal amount of whole blood in a short time. It showed an acceptable performance for precision, linearity and comparison with central laboratory analyzer. It can be useful as a screening tests modality in mobile clinics, ambulances, and field clinics for military use, and for pediatric patients from whom enough sample volume is difficult to obtain.