This is a ready-to-use SOP. Replace every <<FILL: ...>> placeholder with your own specifics, set your document numbers and dates, and route it through your normal document control, review, and approval. A worked filled specimen follows the template so you can see how a completed version reads. Verify every acceptable-intake figure and every cited guidance revision against the current published source before you rely on it; the numbers in this SOP change as regulators update their guidance.
Document control header
| Field | Entry |
|---|---|
| Document title | Nitrosamine Impurity Risk Assessment and Control |
| Document number | <<FILL: SOP-ID, e.g. SOP-QA-041>> |
| Version | <<FILL: version, e.g. 1.0>> |
| Effective date | <<FILL: effective date>> |
| Supersedes | <<FILL: prior version or "New">> |
| Document owner | <<FILL: role, e.g. Head of Quality Assurance>> |
| Applies to | <<FILL: sites / product lines in scope>> |
1. Purpose
This procedure defines how <<FILL: COMPANY NAME>> identifies, assesses, tests for, and controls nitrosamine impurities, including nitrosamine drug-substance-related impurities (NDSRIs), across the marketed and pipeline product portfolio, so that no product exceeds its applicable acceptable intake (AI) and every risk conclusion is documented and defensible.
2. Scope
This procedure applies to every drug substance and drug product manufactured, packaged, or marketed by <<FILL: COMPANY NAME>>, including products manufactured by contract manufacturers under a quality agreement. It covers initial risk assessment, confirmatory analytical testing, acceptable-intake derivation (including the Carcinogenic Potency Categorization Approach, CPCA), regulatory reporting, and the lifecycle triggers that require re-assessment. It does not replace the general impurity control procedures for ordinary organic, inorganic, and residual-solvent impurities under <<FILL: SOP-ID for ICH Q3 impurity control>>.
3. Responsibilities
| Role | Responsibility |
|---|---|
| Quality Assurance (process owner) | Owns this procedure, maintains the product risk-assessment register, gates release on open nitrosamine risk questions |
| Process/analytical chemistry | Evaluates synthetic routes and formulation for amine/nitrosating-agent co-occurrence, proposes control strategy |
| Toxicology | Derives or confirms acceptable intake limits, including CPCA categorization and any read-across or enhanced Ames justification |
| Analytical / QC | Develops and validates confirmatory test methods (LC-MS/MS or GC-MS/MS), performs testing |
| Regulatory affairs | Files risk-assessment conclusions and confirmed findings with the relevant authorities, tracks regional AI figures and deadlines |
| Supply chain / procurement | Obtains and maintains excipient and raw-material nitrite/nitrosamine data from suppliers |
| Change control | Triggers re-assessment against the criteria in section 5.6 |
4. Definitions
- Nitrosamine: a chemical formed when a secondary or tertiary amine reacts with a nitrosating agent (nitrous acid, nitrites, nitrogen oxides).
- NDSRI (nitrosamine drug-substance-related impurity): a nitrosamine formed from the drug substance’s own amine functionality, structurally unique to that molecule.
- Acceptable intake (AI): the maximum daily intake of a nitrosamine, in nanograms per day, judged not to pose an appreciable carcinogenic risk over a defined exposure duration.
- CPCA (Carcinogenic Potency Categorization Approach): a structure-based method assigning a nitrosamine to one of five potency categories, each with a default AI, for use when no compound-specific carcinogenicity data exist.
- Less-than-lifetime (LTL) limit: an AI adjusted upward for a defined, shorter treatment duration than lifetime exposure.
5. Procedure
5.1 Initial risk assessment (every marketed and pipeline product)
- For each product, document the synthetic route (or, for drug product, the formulation and manufacturing process) and identify every step where a secondary or tertiary amine and a nitrosating source could co-occur.
- Screen the API structure itself for a secondary-amine moiety capable of forming an NDSRI.
- Catalog every raw material, reagent, solvent (with particular attention to recovered or recycled streams), and catalyst for nitrite or nitrosating potential.
- Obtain excipient nitrite-content data from suppliers per
<<FILL: SOP-ID for supplier qualification>>; do not assume zero without data. - Evaluate water, equipment, container closure, and cross-contamination pathways.
- Record a conclusion for every product: risk identified (proceed to 5.2) or no risk identified (document the full reasoning; a bare “no risk” conclusion without an assessed rationale is not acceptable).
5.2 Confirmatory testing
- Where risk is identified, develop or apply a validated LC-MS/MS or GC-MS/MS method with a limit of quantitation demonstrated below the AI-derived concentration limit for that product’s maximum daily dose. A method that cannot quantify below the limit cannot support a “not detected” conclusion.
- Test a minimum of
<<FILL: number>>batches spanning the registered process range, including batches made with any recovered solvent or recycled catalyst stream in scope. - Record results against the calculated product-specific limit (see the paired worksheet in section 8).
5.3 Deriving the acceptable intake
- Check whether a compound-specific, regulator-published AI already exists for the nitrosamine identified. Use the current published figure; do not carry forward a figure from a superseded guidance revision.
- If no compound-specific AI exists, apply CPCA: score the compound’s alpha-hydrogen count and position and its activating/deactivating structural features, assign the potency category (PC1 through PC5), and adopt the corresponding default AI.
- Where the CPCA default is being challenged as overly conservative, commission an enhanced Ames test or a documented read-across argument to a structurally related, well-characterized nitrosamine, reviewed and approved by Toxicology before use.
- Apply less-than-lifetime adjustment where the treatment duration is genuinely shorter than lifetime and the shorter duration is documented and defensible.
- Calculate the product-specific concentration limit: AI (ng/day) divided by maximum daily dose (g/day).
5.4 Reporting and corrective action
- Where confirmed nitrosamine levels exceed the applicable AI, notify Regulatory Affairs the same working day.
- Regulatory Affairs reports to the relevant health authority per the current regional reporting timeline and format.
- Implement corrective action: process change, supplier change, reformulation, packaging change, or, where levels cannot be brought within the AI in the required timeframe, market action up to and including withdrawal.
- Re-test to confirm the corrective action is effective before resuming release.
5.5 Documentation
Every risk assessment, whether it concludes risk or no risk, is recorded on the nitrosamine risk assessment record (section 8) and retained in the product’s regulatory/quality file.
5.6 Lifecycle re-assessment triggers
Re-run the risk assessment (section 5.1) whenever any of the following occurs: a synthetic route change, a new or changed raw material or excipient supplier, a new excipient lot from an unqualified source, a recovered-solvent or catalyst-stream change, an equipment or container-closure change, or a regulatory guidance update that changes an AI figure or the CPCA methodology. Change control (per <<FILL: SOP-ID for change control>>) must interrogate nitrosamine risk as a mandatory question on every applicable change request; it is not optional or a “usually not applicable” checkbox.
6. Acceptance criteria
- Every marketed and pipeline product has a documented, dated nitrosamine risk assessment, including products concluded to be at no risk.
- Every confirmatory test method has a demonstrated LOQ below the applicable product-specific limit.
- Every AI used is either a current, cited, compound-specific regulatory figure or a properly derived CPCA category assignment with the scoring rationale on file.
- No product is released with a confirmed nitrosamine level above its AI without an approved, time-bound corrective action plan.
- Change control records show nitrosamine risk was explicitly considered for every applicable change, not silently skipped.
7. Records generated
- Nitrosamine risk assessment record (per product, section 8)
- Confirmatory testing report and method validation package
- CPCA categorization worksheet (see the paired worksheet template)
- Regulatory notification correspondence, where applicable
- Corrective action and re-test records
8. Record: nitrosamine risk assessment
| Field | Entry |
|---|---|
| Product / drug substance | <<FILL>> |
| Assessment date and author | <<FILL>> |
| Synthetic route / formulation reviewed | <<FILL: route summary or reference>> |
| Amine/nitrosating co-occurrence identified? | <<FILL: Yes/No, with detail>> |
| API NDSRI potential screened? | <<FILL: Yes/No, with structural rationale>> |
| Excipient nitrite data obtained? | <<FILL: Yes/No, source>> |
| Conclusion | <<FILL: Risk identified / No risk identified, with reasoning>> |
| If risk identified: nitrosamine(s) named | <<FILL>> |
| AI source | <<FILL: compound-specific regulatory figure / CPCA category and score>> |
| Product-specific limit | <<FILL: ng/g or ppb>> |
| Confirmatory test result | <<FILL: value vs. limit, method ID>> |
| Disposition | <<FILL: no further action / corrective action initiated, reference>> |
| QA approval | <<FILL: name, signature, date>> |
9. References
FDA Guidance, Control of Nitrosamine Impurities in Human Drugs (current revision). EMA Article 5(3) referral outcome and implementation guidance for nitrosamine impurities (current revision). ICH M7(R2), Assessment and Control of DNA Reactive (Mutagenic) Impurities. FDA / EMA guidance on the Carcinogenic Potency Categorization Approach (CPCA), 2023, and subsequent updates. ICH Q9, Quality Risk Management.
Confirm the current version and any published AI figures against the primary source before issue; both FDA and EMA guidance in this area have been revised more than once.
10. Revision history
| Version | Date | Author | Summary of change |
|---|---|---|---|
<<FILL: 1.0>> | <<FILL: date>> | <<FILL: author>> | Initial issue. |
11. Approvals
| Role | Name | Signature | Date |
|---|---|---|---|
| Author | <<FILL>> | ||
| Reviewer (Toxicology) | <<FILL>> | ||
| Approver (Quality Head) | <<FILL>> |
Filled specimen
| Field | Entry |
|---|---|
| Product / drug substance | Example Tablet 250 mg, drug substance Example-API |
| Assessment date and author | 14 August 2026, J. Alvarez (Process Chemistry) |
| Synthetic route / formulation reviewed | Four-step synthesis; step 3 uses a sodium nitrite quench in the presence of a secondary amine intermediate |
| Amine/nitrosating co-occurrence identified? | Yes, step 3 quench |
| API NDSRI potential screened? | Yes; API retains no free secondary amine post-cyclization, low NDSRI concern, documented in structural review SR-2026-014 |
| Excipient nitrite data obtained? | Yes, croscarmellose sodium supplier data on file, nitrite below 1 ppm |
| Conclusion | Risk identified at step 3; proceed to confirmatory testing |
| If risk identified: nitrosamine(s) named | N-nitroso-dimethylamine analog (structure on file), novel NDSRI candidate |
| AI source | No compound-specific data; CPCA scoring places it in PC2 (moderate activating alpha-hydrogen pattern, no offsetting deactivating group) |
| Product-specific limit | AI 100 ng/day / 1 g/day max dose = 100 ng/g = 100 ppb |
| Confirmatory test result | 8 ppb, LC-MS/MS method AM-2026-077, LOQ 2 ppb, three registered-range batches |
| Disposition | No further action; result well within limit with margin; scheduled for re-check on any route or supplier change |
| QA approval | R. Nakamura, signed, 20 August 2026 |
This example shows the pattern regulators expect: a real structural and process rationale for the co-occurrence finding, a documented CPCA category assignment rather than an assumed number, a method with demonstrated sensitivity below the limit, and a disposition tied to actual data with a stated re-check trigger.
Common inspection findings this SOP prevents
- A nitrosamine risk assessment that concludes “no risk” with no documented rationale for a specific product.
- Confirmatory testing performed with a method whose LOQ sits above the limit it is meant to demonstrate compliance with.
- A CPCA category asserted without the scoring rationale on file, so a reviewer cannot verify the assigned AI.
- No re-assessment after a route, supplier, or excipient-lot change, treating the initial risk assessment as permanent.
- Excipient nitrite content assumed rather than obtained from supplier data.
How to adapt this SOP
- Set your document number, owner, and effective date in the header.
- Point section 2’s cross-reference to your actual ICH Q3 impurity-control SOP and section 5.6’s cross-reference to your change control SOP.
- Set the minimum batch-testing number in section 5.2 to match your process validation and regulatory commitments.
- Confirm every AI figure and guidance citation in section 9 against the current published version before issue; do not carry forward a number from a prior guidance revision.
- If your product portfolio includes biologics, cell and gene therapy, or combination products with chemically synthesized components (linkers, small-molecule payloads, excipients), apply the same logic to those synthetic and formulation steps rather than assuming the risk is small-molecule-only.