Search

Rationale: An LC–MS/MS method was established to measure tigecycline in dried blood spots (DBSs). Methods: The DBS specimens obtained by applying 30 μl of blood to filter paper were extracted with hydrogen oxide and subsequently precipitated protein with perchloric acid, then the extract was directly analyzed by liquid chromatography tandem mass spectrometry. A Hypersil GOLD aQ column was utilized for separating the analytes, and detection was carried out in positive and selective reaction monitoring modes. The precursors to product ion transitions m/z 586.3 → 513.1 and m/z 586.3 → 569.2 were monitored for tigecycline, and m/z 473.2 → 456.0 and m/z 473.2 → 367.0 for 9‐amino minocycline as internal standard. Results: The validation parameters of specificity and selectivity, linearity (0.02–5 μg ml−1), sensitivity (limit of quantification 0.02 μg ml−1), intra‐ and interday precision (within 15%) and relative error (within ±15%) were acceptable. The recoveries were from 84.65% to 90.49% and from 85.41% to 95.72% for tigecycline and internal standard, respectively, and the matrix effect was not evident to influence accuracy. The impact of hematocrit on measurement of the analyte was negligible, and after preserving at ambient temperature for 24 h and at 4°C for 1 month it remained steady. Conclusions: The advantages of nonintrusive blood collection and micro‐volume sample requirements make DBS a potent surrogate to conventional venepuncture for sampling. [ABSTRACT FROM AUTHOR]

Rationale: A liquid chromatography/tandem mass spectrometry (LC/MS/MS) method for quantification of caspofungin in dried blood spots (DBS) was developed and validated. Methods: The DBS samples were prepared by spotting whole blood onto Whatman 903 filter paper, drying at room temperature and extracting with 50% methanol and further cleaned by protein precipitation with acetonitrile. Roxithromycin was selected as internal standard, and the separation of the analytes with endogenous ingredients was accomplished on a Hypersil GOLD aQ column with a mobile phase composed of 0.1% formic acid (v/v) and methanol in gradient mode. The detection of the analytes was performed on a triple quadrupole mass spectrometer in positive electrospray ionization mode, and the following selective reaction monitoring (SRM) transitions were monitored: m/z 547.6 → 538.7 and 837.4→ 679.4 for quantification of caspofungin and the internal standard, respectively. Results: The total analytical time was 8 min for each run. The calibration curve exhibited a good linearity over the range from 0.2 to 20 μg/mL and the lower limit of quantification (LLOQ) was 0.2 μg/mL for caspofungin in DBS. The recoveries of caspofungin ranged from 62.64% to 76.69%, and no obvious matrix effect was observed. The intra‐ and inter‐day precision and accuracy were within acceptable limits, and caspofungin in DBS was stable after storage at room temperature for 24 h and at −80°C for 30 days. There was no evident effect of the hematocrit value on the analysis of caspofungin. Conclusions: The proposed method presents an alternative to the conventional venous sampling method, and was successfully utilized for pharmacokinetics study of caspofungin in ICU patients. [ABSTRACT FROM AUTHOR]

An LC-MS/MS method for analysis of daptomycin in dried blood spot (DBS) was established. The DBS samples were prepared by spotting one droplet of blood onto absorbent paper, and were left to dry at room temperature. The DBS samples were extracted with water followed by deproteinization with acetonitrile. A Hypersil GOLD aQ column was applied to chromatographically separate the analyte, and mobile phase at a flow rate of 0.3 mL/min consisted of methanol and 0.1% formic acid. Detection of analyte was performed on a triple quadrupole mass spectrometer in positive mode, and the mass spectrometer was manipulated in selective reaction monitoring (SRM) mode. The SRM transitions m/z 810.9→811.1 and 810.9→640.8 for quantification and qualification of daptomycin and m/z 837.4→679.4 and 837.4→558.3 for roxithromycin used as internal standard were monitored. The calibration curves covering the range of 1-200 μg/mL exhibited good linearity, and lower limit of quantification (LLOQ) was 1 µg/mL for daptomycin in DBS. The proposed method was fully validated, and hematocrit effect on the quantification of daptomycin in DBS was not obvious. The proposed DBS method was non-invasive and required collection of a micro-volume blood, and was successfully utilized to a pharmacokinetics study in seriously ill patients. [ABSTRACT FROM AUTHOR]

Tigecycline, a novel intravenously administered glycylcycline antibiotic, currently plays a key role in the management of complicated multiorganism infections. However, current liquid chromatography with tandem mass spectrometry methods briefly describe parameters and the only reported internal standard was sometimes difficult to obtain. In our study, an updated liquid chromatography with tandem mass spectrometry method for the quantitative analysis of tigecycline in human serum was developed. Sample preparation involved precipitation with 20% trichloroacetic acid. Chromatographic separation of tigecycline and tetracycline (internal standard) was achieved on a Hypersil GOLD C18 column using gradient elution. The selected reaction monitoring transitions were performed at m/ z 586.1→513.2 for tigecycline and m/ z 445.1→410.2 for tetracycline. The assay was linear over the concentration range of 5-2000 ng/mL. The intra- and interday precisions at three concentration levels (10, 100, and 1600 ng/mL) were <15% and their accuracies were within the range of 95.1-106.1%. The mean recovery ranged from 94.3 to 105.6% and the matrix effect from 92.1 to 97.6%. Tigecycline was stable under all tested conditions. This validated method was successfully applied to a pharmacokinetic study in critically ill patients. The data demonstrated that our method allows quantification of tigecycline in serum in a quick and reliable manner for widespread application. [ABSTRACT FROM AUTHOR]

B vitamins in the human distal gut are primarily derived from the gut microbiota because daily dietary vitamins are fully absorbed in the small intestine under normal dietary and physiological conditions. Quantitative determination of B vitamins in the distal gut and faecal samples is crucial for understanding the intricate relationship between gut B vitamins, gut microbiota, and host health. In this study, we developed a rapid, robust, and reliable method with a simple extraction procedure for the simultaneous analysis of seven B vitamins in human faeces using high-performance liquid chromatography-electrospray ionisation-tandem mass spectrometry (HPLC-ESI-MS/MS) with stable isotope-labelled internal standards. A protein precipitation approach using methanol as the precipitant was employed to extract vitamin B from human faecal samples. Seven B vitamins were adequately separated and quantified within 9 min by HPLC-ESI-MS/MS with a Pursuit PFP column (2.0 ×150 mm, 3.0 µm), including vitamins B1, B2, B3, B5, pyridoxic acid, pyridoxine, and B7. The lower limits of quantification were within the range of 0.1–25 ng mL−1. The intra-day and inter-day precision and accuracy were both within 15 %. The validated method was successfully applied to 55 faecal samples collected from healthy individuals, patients with type 2 diabetes, and obese patients. Compared with healthy controls, obese patients had lower faecal concentrations of vitamins B1 and B3 and pyridoxic acid, whereas patients with type 2 diabetes had lower faecal concentrations of vitamins B1 and B5. [Display omitted] • Development of an HPLC-MS/MS method for quantification of faecal B vitamins. • Application to faecal samples collected from healthy volunteers and patients. • Changes in faecal B vitamins profile in obesity and type 2 diabetes. [ABSTRACT FROM AUTHOR]