A Liquid Chromatography-mass Spectrometry Method to Determine the Content of Genotoxic Impurity Piperidine in Rimonabant.

Objective: To establish and determine the content of the genotoxic impurity piperidine in the active pharmaceutical ingredient (API) of rimonabant using a liquid chromatography-mass spectrometry (LC-MS) method. This study underscores the importance of detecting piperidine due to its potential health risks, including carcinogenic and mutagenic effects, thus highlighting the critical need for rigorous quality control in pharmaceutical products. Methods: An Atlantis C18 column (5 µm, 3.9×100 mm) was chosen for separation due to its high efficiency and selectivity for piperidine, with a gradient elution of 0.05% formic acid-water (A) and methanol (B) as the mobile phase at a flow rate of 1.0 mL/min. The column temperature was optimized at 30°C to ensure peak resolution and sensitivity, the injection volume was set to 5.0 µL to minimize sample consumption while maintaining detectability, and the analysis time was kept at 7 min for efficient throughput. Results: Piperidine demonstrated excellent linearity in the concentration range of 0.03-0.40 µg/mL (R>0.99), with a detection limit of 0.01010 µg/mL. This detection limit is significantly lower than regulatory thresholds, indicating the method's high sensitivity compared to existing methods and its adequacy for regulatory compliance in pharmaceutical quality control. Conclusion: This LC-MS method not only demonstrated high accuracy, good repeatability, and strong durability but also sets a benchmark for future research, regulatory practices, and pharmaceutical quality control. By accurately detecting low levels of genotoxic impurities like piperidine, this method supports the development of safer drug formulations and underscores the importance of stringent quality control measures in the pharmaceutical industry.

A high-throughput UHPLC-MS/MS method for the determination of eight anti-tumor drugs in plasma.

Rapidly developing UHPLC-MS/MS bioassays with high throughput and quality are challenging yet desired in routine clinics. METHODS & RESULTS: A high-throughput UHPLC-MS/MS bioassay has been built for simultaneously quantifying gefitinib, ruxolitinib, dasatinib, imatinib, ibrutinib, methotrexate, cyclophosphamide and paclitaxel. After the protein precipitation with methanol, samples were separated on an Acquity BEH C18 column following a gradient elution system with methanol and 2 mM ammonium acetate in water at 40 °C with a run time of 3 min (flow rate 0.4 mL/min). Mass quantification in the positive ion SRM mode was then performed with electrospray ionization. The method of specificity, linearity, accuracy, precision, matrix effects, recovery, stability, dilution integrity and carryover were all validated as per the guideline of the China Food and Drug Administration whose values met the admissible limits. Application of the bioassay to therapeutic drug monitoring revealed important variability in the studied anti-tumour drugs. CONCLUSION: This validated approach was shown to be reliable and effective in clinical management, being a valuable support in therapeutic drug monitoring and subsequent individualized dosing optimization.

Influence of UGT2B7, UGT1A4 and ABCG2 Polymorphisms on the Pharmacokinetics and Therapeutic Efficacy of Lamotrigine in Patients with Epilepsy.

BACKGROUND AND OBJECTIVES: A substantial inter-individual variability has been observed in the pharmacokinetics of lamotrigine. The aim of the study was to investigate the impact of genetic polymorphism of the metabolizing enzymes (UGT2B7, UGT1A4) and transporter (ABCG2) on the pharmacokinetics and therapeutic efficacy of lamotrigine in patients with epilepsy. METHODS: The genetic analysis of single-nucleotide polymorphisms was conducted using polymerase chain reaction sequence. High-performance liquid chromatography/tandem mass spectrometry was employed to measure the plasma concentrations of lamotrigine. The efficacy of lamotrigine was assessed by evaluating the reduction rate of epileptic seizure frequency. RESULTS: This study included a cohort of 331 patients who were treated with lamotrigine as monotherapy. A linear correlation was observed between the lamotrigine concentration and daily dose taken (r = 0.58, p < 2.2e-16). Statistically significant differences were found in both the median plasma concentration and dose-adjusted concentration (C/D ratio) when comparing the ineffective to the effective group (p < 0.05). Multivariate analysis showed that UGT1A4 rs2011425, ABCG2 rs2231142 polymorphisms and age had a significant relationship with the lamotrigine concentrations (p < 0.05). Age was a predictive factor for C/D ratio (p < 0.001). Lamotrigine concentration and weight were good predictive factors for effective seizure outcomes (odds ratio [OR] = 0.715, 95% CI 0.658-0.776, p < 0.001; OR = 0.926, 95% CI 0.901-0.951, p < 0.001, respectively). The cut-off values of lamotrigine trough concentrations for clinical outcomes in the age-related groups were determined as 2.49 µg/ml (area under the receiver-operating characteristic curve [AUC]: 0.828, 95% CI 0.690-0.966), 2.70 µg/ml (AUC: 0.805, 95% CI 0.745-0.866) and 3.25 µg/ml (AUC: 0.807, 95% CI 0.686-0.928) for the adult group, adolescent group, and toddler and school-age group, respectively. CONCLUSIONS: UGT1A4 rs2011425 and ABCG2 rs2231142 were correlated with lamotrigine concentrations. Lower lamotrigine trough concentration was found in the ineffective group and the troughs were associated with seizure outcomes.

An effective pretreatment technique based on multi-walled carbon nanotubes to reduce the matrix effect in plasma samples analyzed by a new type probe electrospray ionization method.

The quantitative analysis of drug plasma samples plays an important role in the drug development and drug clinical use. Our research team developed a new electrospray ion source-Micro probe electrospray ionization (µPESI) in the early stage, which was combined with mass spectrometry (µPESI-MS/MS) showing good qualitative and quantitative analysis performance. However, matrix effect severely interfered the sensitivity in µPESI-MS/MS analysis. To solve this problem, we recently developed a Solid-phase purification method based on multi-walled carbon nanotubes (MWCNTs), which was used for removing matrix interfering substances (especially phospholipid compounds) in the preparation of plasma samples, so as to reduce the matrix effect. In this study, aripiprazole (APZ), carbamazepine (CBZ) and omeprazole (OME) were used as representative analytes, the quantitative analysis related to the plasma samples spiked with the analytes above and the mechanism of the MWCNTs to reduce matrix effect were both investigated. Compared with the ordinary protein precipitation, MWCNTs could reduced the matrix effect for several to dozens of times, which resulting from the removement of phospholipid compounds from the plasma samples by MWCNTs in the selective adsorption manner. We further validated the linearity, precision and accuracy of this pretreatment technique by the µPESI-MS/MS method. These parameters all met the requirements of FDA guidelines. It was showed that MWCNTs have a good application prospect in the drug quantitative analysis of plasma samples using the µPESI-ESI-MS/MS method.

Prevalence of common mental disorders among medical students in China: a systematic review and meta-analysis.

Background: The prevalence of mental distress is common for medical students in China due to factors such as the long duration of schooling, stressful doctor-patient relationship, numerous patient population, and limited medical resources. However, previous studies have failed to provide a comprehensive prevalence of these mental disorders in this population. This meta-analysis aimed to estimate the prevalence of common mental disorders (CMDs), including depression, anxiety, and suicidal behaviors, among medical students in China. Methods: We conducted a systematic search for empirical studies on the prevalence of depression, anxiety, suicide attempt, suicide ideation, and suicide plan in Chinese medical students published from January 2000 to December 2020. All data were collected pre-COVID-19. The prevalence and heterogeneity estimations were computed by using a random-effects model and univariate meta-regression analyses. Results: A total of 197 studies conducted in 23 provinces in China were included in the final meta-analysis. The prevalence data of depression, anxiety, suicide attempt, suicide ideation, and suicide plan were extracted from 129, 80, 21, 53, and 14 studies, respectively. The overall pooled crude prevalence for depression was 29% [38,309/132,343; 95% confidence interval (CI): 26%-32%]; anxiety, 18% (19,479/105,397; 95% CI: 15%-20%); suicide ideation, 13% (15,546/119,069; 95% CI: 11%-15%); suicide attempt, 3% (1,730/69,786; 95% CI: 1%-4%); and suicide plan, 4% (1,188/27,025; 95% CI: 3%-6%). Conclusion: This meta-analysis demonstrated the high prevalence of CMDs among Chinese medical students. Further research is needed to identify targeted strategies to improve the mental health of this population.