Performance Characteristics of Mass Spectrometry-Based Analytical Procedures for Quantitation of Nitrosamines in Pharmaceuticals: Insights from an Inter-laboratory Study.

With the discovery of carcinogenic nitrosamine impurities in pharmaceuticals in 2018 and subsequent regulatory requirements for risk assessment for nitrosamine formation during pharmaceutical manufacturing processes, storage or from contaminated supply chains, effective testing of nitrosamines has become essential to ensure the quality of drug substances and products. Mass spectrometry has been widely applied to detect and quantify trace amounts of nitrosamines in pharmaceuticals. As part of an effort by regulatory authorities to assess the measurement variation in the determination of nitrosamines, an inter-laboratory study was performed by the laboratories from six regulatory agencies with each of the participants using their own analytical procedures to determine the amounts of nitrosamines in a set of identical samples. The results demonstrated that accurate and precise quantitation of trace level nitrosamines can be achieved across multiple analytical procedures and provided insight into the performance characteristics of mass spectrometry-based analytical procedures in terms of accuracy, repeatability and reproducibility.

International Regulatory Collaboration on the Analysis of Nitrosamines in Metformin-Containing Medicines.

Recalls of some batches of metformin have occurred due to the detection of N-nitrosodimethylamine (NDMA) in amounts above the acceptable intake (AI) of 96 ng per day. Prior to the recalls, an international regulatory laboratory network had been monitoring drugs for nitrosamine impurities with each laboratory independently developing and validating multiple analytical procedures to detect and measure nitrosamines in metformin drugs used in their jurisdictions. Here, we provide an overview of the analysis of metformin active pharmaceutical ingredients (APIs) and drug products with 1090 samples (875 finished dosage forms (FDFs) and 215 API samples) tested beginning in November of 2019 through July of 2020. Samples were obtained internationally by a variety of approaches, including purchased, received from firms via information requests or selected by regional regulatory authorities (either at wholesalers or during GMP inspections). Only one nitrosamine (NDMA) was detected and was only present in some batches of metformin products. For API samples, 213 out of 215 lots tested had no measurable level of NDMA. For FDF samples tested, the number of batches with NDMA above the AI amount for patient safety was 17.8% (156/875). Based on these data, although the presence of NDMA was of concern, 82.2% of the samples of metformin drug products tested met quality and safety standards for patients. Regulatory agencies continue to collaborate extensively and work with marketing authorization holders to understand root causes of nitrosamine formation and agree on corrective actions to mitigate the presence of NDMA in future metformin batches.

Adaptive Mechanisms of Renal Bile Acid Transporters in a Rat Model of Carbon Tetrachloride-Induced Liver Cirrhosis.

BACKGROUND: Acute kidney injury (AKI) is common in advanced liver cirrhosis, a consequence of reduced kidney perfusion due to splanchnic arterial vasodilation and intrarenal vasoconstriction. It clinically manifests as hepatorenal syndrome type 1, type 2, or as acute tubular necrosis. Beyond hemodynamic factors, an additional mechanism may be hypothesized to explain the renal dysfunction during liver cirrhosis. Recent evidence suggest that such mechanisms may be closely related to obstructive jaundice. METHODS: Given the not completely elucidated role of bile acids in kidney tissue damage, this study developed a rat model of AKI with liver cirrhosis induction by carbon tetrachloride (CCl4) inhalation for 12 weeks. Histological analyses of renal and liver biopsies were performed at sacrifice. Organic anion tubular transporter distribution and apoptosis in kidney cells were analyzed by immunohistochemistry. Circulating and urinary markers of inflammation and tubular injury were assayed in 21 treated rats over time (1, 2, 4, 8, and 12 weeks of CCl4 administration) and 5 controls. RESULTS: No renal histopathological alterations were found at sacrifice. Comparing treated rats with controls, organic anion transporters were differentially expressed and localized. High serum bile acid values were detected in cirrhotic animals, while caspase-3 staining was negative in both groups. Increased levels of serum inflammatory and urinary tubular injury biomarkers were observed during cirrhosis progression, with a peak after 4 and 8 weeks of treatment. CONCLUSIONS: These findings suggest possible adaptive tubular mechanisms for bile acid transporters in response to cirrhosis-induced AKI.