Identification, isolation, characterization, and UHPLC quantification of potential genotoxic impurities in linagliptin.

During the stress testing of linagliptin, one unknown degradation product (impurity I) on acidic conditions was detected by using high-performance liquid chromatography and subsequently isolated, identified, and characterized by the spectral data (MS, MS/MS, 1D and 2D NMR spectroscopy, and IR spectroscopy) and finally subjected for mechanism analysis. The degradation product (impurity I) and another process-related impurity (impurity II) of linagliptin were found to contain the structural alerts of N-acylated aminoaryl and alkyl halide, respectively, which were both potential genotoxic substances. Hence, a rapid and facile ultra high performance liquid chromatography method was developed for the simultaneous determination of these two potential genotoxic impurities at ppm levels in linagliptin. The factors involved in the method development were discussed and this method was fully validated as per International Conference on Harmonization of Technical Requirements for Registration of Pharmaceuticals for Human Use guidelines, which proved the method sensitive, selective, and robust. The presented method has been successfully applied to the analysis of real samples from multiple batches. This study will help to risk management of possible genotoxic impurities present in linagliptin.

Evaluation system for arrhythmogenic potential of drugs using human-induced pluripotent stem cell-derived cardiomyocytes and gene expression analysis.

In recent years, human-induced pluripotent stem cell-derived cardiomyocytes (hiPS-CMs) have been widely used to develop evaluation systems for drug cardiotoxicity, including the arrhythmia caused by QT prolongation. To accurately assess the arrhythmogenic potential of drugs, associated with QT prolongation, we developed an evaluation system using hiPS-CMs and gene expression analysis. hiPS-CMs were treated with 8 arrhythmogenic and 17 non-arrhythmogenic drugs at several concentrations for 24 hr to comprehensively analyze gene expression. The results showed that 19 genes were upregulated in the arrhythmogenic drug-treated cells compared with their expression levels in the non-treated and non-arrhythmogenic drug-treated cells. The arrhythmogenic risks of the drugs were evaluated by scoring gene expression levels. The results indicated that arrhythmogenic risks could be inferred when cells were treated at a concentration 100 times higher than the maximum blood concentration of the drug. Thus, we succeeded in developing a system for evaluation of the arrhythmogenic potential of drugs using gene expression analysis.