Development and Validation of UPLC Tandem Mass Spectrometry Assay for Ceftibuten and Sulbactam in Human Plasma.

A sensitive and rapid ultra-performance liquid chromatography coupled with -tandem mass spectrometry (UPLC-MS/MS) method was developed and validated to determine ceftibuten (CTB) and sulbactam (SUL) in human plasma. An ACQUITY UPLC HSS T3 C18 (2.1 × 100 mm), 1.8 µm column with gradient elution of water (0.1% formic acid) and acetonitrile was used for separation at a flow rate of 0.2 mL/min. This method involves a simple sample preparation with acetonitrile. The calibration curves of CTB and SUL in plasma showed good linearity over the concentration range of 0.50-25 µg/mL and with a correlation coefficient (r2) >0.99. This method was validated in terms of selectivity, linearity, precision, accuracy and stability. High precision was obtained with coefficients of variation <15%. Excellent recovery in the range of 90-104% was achieved for CTB and SUL was 86-110%. The method has the potential utility to support pharmacometric modeling in clinical practice and biopharmaceutic studies.

Altered Arylamine N-acetyltransferase 1 and miR-1290 Levels in Childhood Acute Lymphoblastic Leukemia: A Pilot Study.

BACKGROUND/AIM: Arylamine N-acetyltransferase 1 and 2 (NAT1 and NAT2) are drug-metabolizing enzymes that play a key role in the development of acute lymphoblastic leukemia (ALL). MATERIALS AND METHODS: This study evaluated NAT1 and NAT2 mRNA and protein expression and their enzymatic activity in peripheral blood mononuclear cells (PBMC) from patients with ALL (n=20) and healthy children (n=19) and explored the mechanisms that regulate these enzymes in ALL such as microRNAs (miR-1290, miR-26b) and SNPs. RESULTS: PBMC from patients with ALL showed a decrease in NAT1 mRNA and protein expression. In addition, NAT1 enzymatic activity was decreased in patients with ALL. There was no influence of SNP 559 C>T or 560 G>A on low NAT1 activity. The lower expression of NAT1 might be related to the loss of acetylated histone H3K14 in the NAT1 gene promoter in patients with ALL and the higher relative expression of miR-1290 in the plasma of patients with relapsed ALL compared with healthy controls. There were significantly fewer CD3+/NAT1+ double-positive cells in patients who relapsed compared with control subjects. Based on a t-distributed stochastic neighbor embedding algorithm, CD19+ cells that reappeared in patients with relapse showed low NAT1 expression. In contrast, for NAT2, there were no significant results. CONCLUSION: The expression and function of NAT1 and miR-1290 levels could be involved in modulating immune cells altered in ALL.

Simultaneous determination of four serotonin selective reuptake inhibitors by an UPLC MS-MS method with clinical application in therapeutic drug monitoring.

An analytical method of ultra-high performance liquid chromatography coupled to tandem mass spectrometry detection was developed and validated for the simultaneous quantification in plasma of four selective serotonin reuptake inhibitor antidepressants: sertraline, escitalopram, paroxetine, fluoxetine, and its metabolite norfluoxetine. A simple protein precipitation was performed with acetonitrile containing 100 ng/mL of indomethacin, which was used as internal standard. Chromatographic separation was carried out on an Acquity BEH C18 column with isocratic elution of the mobile phase consisting of 5 mmol/L ammonium acetate with 0.1% formic acid (A) and acetonitrile (B) at a 60:40 proportion, respectively. The flow rate was 0.4 mL/min with a run time of 5 min. A positive electrospray ionization source was used for detection. The method was linear in a range of 5-800 ng/mL, with determination coefficients greater than 0.991. The accuracy ranged from 91% to 112% for intra-assay and from 89% to 112% for inter-assay. The variation coefficients ranged from 3.1% to 14.88% for intra-assay and from 3.60% to 14.74% for inter-assay precision. The method was successfully applied for the analysis of 73 samples from patients under treatment with these antidepressants; 36.9% of the samples had concentrations outside therapeutic ranges. This method can be applied for routine analysis in clinical practice, simplifying sample processing, reducing analysis time and consequently the costs associated with it.