Never Blend Different Product Lots Without Prior QA Approval

Do Not Blend Product Lots Without QA-Approved Justification

Remember: GMP strictly forbids blending of different product lots unless there is written QA approval supported by scientific and regulatory justification.

Why This Matters in GMP

Blending of lots, especially without understanding the root cause of rejection or variation, can mask quality issues and undermine product traceability. Lot mixing can dilute or average out specification failures, potentially placing non-conforming product into the market. GMP requires that each lot be individually assessed, controlled, and traceable. QA plays a vital role in reviewing the need for blending and ensuring such decisions are risk-assessed, justified, and well-documented to preserve product quality and batch history.

Also Read: Documenting Environmental Monitoring: Forms, Intervals and Review

Regulatory and Compliance Implications

FDA 21 CFR Part 211.170 prohibits blending of different lots to meet specifications unless permitted in validated processes and justified. EU GMP Chapter 5 stipulates that lot mixing is only allowed under defined, controlled conditions with QA oversight. WHO GMP and Schedule M echo this, emphasizing blending must be scientifically supported and not used to hide batch failures. Inspectors assess blending justifications, QA approvals, validation data, and risk evaluations. Unauthorized blending may lead to warnings, product rejections, or recalls.

Implementation Best Practices

Develop an

SOP that outlines when and how lot blending may be permitted, including risk analysis requirements.

Obtain prior written approval from QA, with supporting documentation for each blending decision.

Ensure blended lots are tested for identity, potency, uniformity, and stability as a new batch.

Document complete traceability of each component lot and maintain integrated batch records.

Use blending only when validated and defined in regulatory filings, such as product dossiers or BMRs.

Regulatory References

FDA 21 CFR Part 211.170 – Reserve Samples and Lot Control
EU GMP Chapter 5 – Blending and Lot Traceability
WHO GMP – Risk-Based Blending Guidance
Schedule M – Lot Mixing and Quality Oversight