Analysis of Pharmaceuticals’ Impurity - Regulations and Analysis for Carcinogenic Substances -

Significance of topic

DNA-reactive impurities in pharmaceuticals, such as nitrosamines and sulfonate esters, present a potential carcinogenic risk at trace levels. Regulatory frameworks now classify and limit these compounds to ensure drug safety.

Scope and objectives of the study

This application note reviews international guidelines for carcinogenic impurities in drug products and illustrates analytical strategies for detecting N-nitrosodimethylamine (NDMA), N-nitrosodiethylamine (NDEA), and related compounds across various APIs.

Methodological overview

The regulatory context includes ICH Q3 (residual solvents), Q3C/Q3D (solvents and elemental impurities) and M7 (DNA-reactive mutagenic impurities). Impurities are classified into five classes according to mutagenicity data or (Q)SAR predictions, with thresholds based on compound-specific potency or TTC (1.5 µg/person/day). Analytical approaches employ headspace GC-MS, direct injection GC-MS/MS, LC-MS/MS, and QTOF LC-MS to achieve sub-ng/mL detection limits.

Main findings and discussion

In sartan drugs (valsartan, losartan, olmesartan), headspace GC-MS achieved LOQs down to 0.05 ppm for NDMA. GC-TQ-MS/MS assays quantified seven nitrosamines at 2.5–100 ng/mL with R2>0.999 and recoveries within ±15%. LC-MS/MS methods reached LOQs of 0.1 ng/mL for six nitrosamines. Ranitidine analysis using QTOF LC-MS yielded S/N>13 at 1 ng/mL and 0.11 ppm NDMA in product. Metformin analysis via GC-TQ-MS/MS detected NDMA down to 0.3 ng/mL with recovery >85%. Mesylate, besylate, and tosylate esters (MMS, EMS, IMS; MBS, EBS, IBS; MTS, ETS, ITS) were effectively analyzed after headspace derivatization, with LOQs near 1 ng/mL and recoveries 86–110%.

Practical implications

Validated workflows enable reliable monitoring of trace carcinogenic impurities, supporting GMP compliance and routine QC in pharmaceutical manufacturing.

Used instrumentations

• Shimadzu HS-20 headspace sampler
• Shimadzu GCMS-QP2020 NX
• Shimadzu GCMS-TQ8050 NX
• Shimadzu LCMS-8060
• Shimadzu LCMS-9030

Future trends and opportunities

Advances in high-resolution MS, automation, and multi-residue screening will further reduce detection limits, streamline workflows, and expand impurity profiling across diverse drug modalities.

Conclusion

The integration of ICH regulatory guidance with sensitive MS-based assays provides a robust framework for controlling carcinogenic impurities, ensuring pharmaceutical quality and patient safety.

References

• ICH M7 guideline, Assessment and Control of DNA-Reactive (Mutagenic) Impurities, 2014.
• ICH Q3C and Q3D guidelines, Residual Solvents and Elemental Impurities.
• FDA NDMA/NDEA Headspace GC-MS and Direct Injection GC-MS methods.
• FDA five-nitrosamine GC-MS/MS method for sartan drugs.
• OMCL GEON analytical methods, European Medicines Control Laboratories Network.
• HSA NDMA in metformin GC-HRAM-MS method.
• European Pharmacopoeia methods for sulfonate esters.