Overcoming the challenges of nitrosamine impurities in drugs

Significance of the Topic

Nitrosamine impurities are classified as potent mutagenic carcinogens by ICH and IARC, posing critical safety concerns in pharmaceuticals. The 2018 valsartan recall highlighted the need for trace-level monitoring of N-nitrosodimethylamine (NDMA), N-nitrosodiethylamine (NDEA) and related nitrosamines at limits below 0.03 ppm under cGMP regulations.

Study Objectives and Overview

This article reviews comprehensive analytical strategies for detecting nitrosamine impurities in active pharmaceutical ingredients and finished dosage forms. It examines advanced gas chromatography–mass spectrometry (GC–MS) and liquid chromatography–MS techniques, with emphasis on headspace sampling, derivatization requirements and high-resolution accurate-mass screening to meet and anticipate regulatory requirements.

Methodology and Instrumentation

Analytical approaches include static and dynamic headspace GC–MS, direct liquid injection GC–MS/MS, and Orbitrap GC–MS. Methods employ single-quadrupole SIM, triple-quadrupole SRM/MRM and full-scan accurate-mass acquisition. Sample preparation ranges from no-derivatization headspace for volatile nitrosamines to derivatization for less volatile compounds such as NMBA.

Used Instrumentation

• Thermo Scientific TriPlus 500 and TriPlus RSH Headspace Autosamplers
• Thermo Scientific AS 1310 Liquid Autosampler
• Thermo Scientific ISQ 7000 Single Quadrupole GC–MS System
• Thermo Scientific TSQ 9000 Triple Quadrupole GC–MS/MS System with AEI Ion Source
• Thermo Scientific Exactive GC Orbitrap Analytical System

Key Findings and Discussion

Static headspace GC–MS achieved LOQs of 0.015 ppm for NDMA and 0.030 ppm for NDEA, surpassing FDA requirements. GC–MS/MS methods delivered LODs down to 0.0002 ppm, with peak area repeatability below 8% RSD. The AEI ion source improved sensitivity to sub-0.5 ng/mL levels. Orbitrap GC–MS enabled combined SIM and full-scan screening with sub-1 ppm mass accuracy, facilitating targeted analysis and retrospective identification of VOCs and residual solvents.

Benefits and Practical Applications

These validated methods ensure high sensitivity and selectivity to avoid false positives, streamline high-throughput cGMP workflows, and support compliance with FDA, EMA and ICH guidelines. Compliance-ready data software provides secure instrument control, automated quantitative analysis and 21 CFR Part 11 adherence.

Future Trends and Opportunities

As regulatory nitrosamine limits tighten, demand for ultra-trace detection will grow. Advanced ionization technologies, high-resolution MS and enhanced screening workflows will enable broader impurity profiling. Integration of automated data processing, machine learning and real-time monitoring may further improve laboratory efficiency and risk mitigation.

Conclusion

Advanced GC–MS and GC–MS/MS platforms, complemented by high-resolution Orbitrap technology and flexible sample introduction, address the challenges of nitrosamine impurity analysis. These robust solutions enable pharmaceutical laboratories to ensure patient safety, maintain cGMP compliance and adapt to evolving regulatory requirements.

References

1. World Health Organization. Information Note on Nitrosamine Impurities in Pharmaceuticals.
2. International Council for Harmonisation. ICH Guideline M7(R1): Assessment and Control of DNA Reactive Mutagenic Impurities in Pharmaceuticals.
3. International Agency for Research on Cancer. IARC Monographs on the Evaluation of Carcinogenic Risks to Humans, Volume 89.
4. European Medicines Agency. Temporary Interim Limits for NMBA, DIPNA and EIPNA in Sartan Medicines (EMA/351053/2019 Rev 1).
5. US Food and Drug Administration. Combined NDMA and NDEA Impurity Assays by GC/MS and GC–MS/MS Methods.
6. US Food and Drug Administration. Important Information about NDMA Impurities in Ranitidine Products.
7. United States Pharmacopeia. USP <467> Organic Volatile Impurities, Chemical Tests.