LOT ACCEPTANCE RATE (LAR) IN PHARMA
What is Lot Acceptance Rate?
Lot means Batch. Lot Acceptance Rate is percentage of lots (batches) that are accepted and released for distribution out of total lots manufactured in a given period.
It is one of the 4 main Quality Metrics proposed by FDA in Quality Metrics Guidance 2015.
Simple meaning – Out of 100 batches you made, how many batches passed and went to market? If 98 passed and 2 rejected, LAR is 98%.
LAR shows how well your manufacturing process is under control. High LAR = Process is robust and under control. Low LAR = Process is not robust, many failures, poor process validation.
Formula of LAR
Other Names: Some companies call it as Batch Acceptance Rate or Lot Rejection Rate (Opposite).
Formula for Rejection Rate:
Lot Rejection Rate = (Number of Lots Rejected / Total Number of Lots Manufactured) x 100
Or = 100 – LAR
Example 1:
Total batches manufactured in 2024 = 250
Batches accepted and released = 242
Batches rejected = 8
LAR = (242 / 250) x 100 = 96.8%
Rejection Rate = 3.2%
Example 2 – Product Wise:
Product A: 100 batches made, 99 accepted -> LAR 99% (Excellent)
Product B: 50 batches made, 40 accepted -> LAR 80% (Poor, need investigation)
What Counts as Rejected Lot?
As per FDA, a lot is considered rejected if:
- Batch failed to meet specification (OOS not invalidated)
- Batch rejected during in-process testing
- Batch rejected due to deviation – Critical deviation
- Batch rejected due to environmental monitoring failure (for sterile)
- Batch rejected during visual inspection (for injectables)
- Batch rejected during packaging – Mix-up, labeling error
Not Counted as Rejected:
- Batch under investigation (not yet accepted or rejected) – Excluded from calculation till final decision
- Batch rejected due to lab error where retest passed – If OOS invalidated as lab error with proof, that batch is not counted as rejected
What is Good LAR? – Industry Benchmark
– Excellent LAR: > 98% – World class manufacturing, process is well validated
– Good LAR: 95% – 98% – Acceptable, but need to check rejection reasons
– Average: 90% – 95% – Need improvement, investigate root cause of rejections
– Poor / Red Flag: < 90% - Process not under control, FDA will ask questions, risk of warning letter Note: For sterile injectables, expectation is higher – LAR should be > 99% because one contaminated batch can cause death. For oral tablets, 95-97% is okay.
Why LAR is Important? – FDA Perspective
- Shows Process Capability: If LAR is low, it means your process validation is poor. Your process cannot consistently make good product.
- Risk-Based Inspection: FDA uses LAR for risk-based inspection. If LAR is low, FDA will inspect early because that site has more quality failures.
- Drug Shortage Indicator: Low LAR leads to drug shortages. If you reject 20% batches, you will have less product to supply, may cause shortage in market.
- Cost of Poor Quality: Every rejected batch is loss – API loss, time loss, manpower loss. One batch rejection can cost 20-50 lakhs. High LAR saves money.
Reasons for Low LAR – Why Batches Get Rejected?
| Reason for Rejection | Example | How to Prevent |
|---|---|---|
| 1. OOS in Finished Product | Assay low, Dissolution fail, Impurity high, Content uniformity fail | Improve blending, granulation, compression parameters |
| 2. In-Process Failure | Blend uniformity fail, LOD high, Hardness fail | Better process validation, PAT tools |
| 3. Deviation / Human Error | Wrong material added, Wrong label, Cleaning failure | Training, Automation, Barcode scanning |
| 4. Environmental Monitoring Failure (Sterile) | EM plate fail, Particle count fail in Grade A | Improve aseptic behavior, Better gowning, Isolator |
| 5. Visual Inspection Failure (Injectables) | High % rejection due to particles, Crack | Improve washing, De-pyrogenation, Better inspection machine |
| 6. Stability Failure | Assay decreasing in stability, Impurity increasing | Improve formulation, Better packaging |
| 7. Packaging Error | Mix-up, Missing leaflet, Wrong carton | Line clearance, Vision system, Checkweigher |
How to Investigate Rejected Lot?
1. Immediate Action: Put batch on hold, inform QA, block in ERP, prevent distribution.
2. Investigation: Same as OOS investigation – Phase 1 Lab, Phase 2 Manufacturing.
3. Check Other Batches: Is same problem in other batches of same product? If yes, it is systemic failure, not isolated.
4. Impact Assessment: Did already distributed batches have same problem? Need recall?
5. Root Cause: Use 5 Whys, Fishbone. Find why failure happened.
6. CAPA: Corrective action for this batch (rejection, rework if allowed) and Preventive action for future batches.
7. Documentation: All rejection must be documented in APQR and Quality Metrics trending.
Some companies rework rejected batch to make LAR look good. FDA allows rework only if it is approved in original filing and validated. You cannot rework sterile injectables or do repeated reprocessing to hide rejection. This is data manipulation. If you rework, you must show rework batch data separately and include original rejection in LAR calculation. You cannot exclude rejected batch from LAR if you reworked it.
How to Improve LAR?
- 1. Robust Process Validation: Do proper 3 batch validation, not just paperwork. Understand critical process parameters (CPP) and critical quality attributes (CQA).
- 2. Quality by Design (QbD): Design formulation and process such that it can tolerate small variations.
- 3. Automation: Reduce human error by automation – Auto dispensing, Barcode scanning, Automated visual inspection.
- 4. Training: Most rejections are due to human error. Give good training to operators and analysts.
- 5. Preventive Maintenance: Calibrate and maintain equipment – HPLC, Compression machine, Filling machine.
- 6. Raw Material Control: Test API and excipients properly. Many failures due to poor quality raw material.
- 7. Trend Analysis: Every month review LAR product-wise. If Product B LAR is 80% for 3 months, do deep dive investigation.
LAR Calculation Example – Monthly Trending
| Month | Total Lots Made | Lots Accepted | Lots Rejected | LAR | Remarks |
|---|---|---|---|---|---|
| Jan | 20 | 20 | 0 | 100% | Excellent |
| Feb | 22 | 19 | 3 | 86.3% | Poor – 3 batches due to dissolution fail |
| Mar | 25 | 24 | 1 | 96% | Good, CAPA taken for dissolution |
| Apr | 23 | 23 | 0 | 100% | Improved after CAPA |
This trend shows improvement after CAPA. This is what FDA wants to see – Use metrics to improve.
Relation of LAR with Other Quality Metrics
– If IOOSR is high (many OOS shown as lab error), LAR will look artificially high because you are not rejecting batches, you are invalidating OOS and releasing.
– If LAR is high but PQCR is also high (many market complaints), it means your in-plant testing is weak. You are releasing bad batches that later get complaints in market.
– Good company: LAR high (98%), IOOSR low (20%), PQCR low (<100 per million). This shows honest testing and good control.
– Bad company: LAR high (99%), IOOSR high (85%), PQCR high (400 per million). This shows you are hiding OOS as lab error and releasing bad product, which later gets complaints.
Conclusion: Lot Acceptance Rate is simplest but most powerful Quality Metric. It directly shows how robust your process is. Don’t try to artificially increase LAR by invalidating OOS or doing unapproved rework. Focus on improving process validation, reducing human error and improving raw material control. If LAR is consistently above 98%, it means your plant is under control. If LAR falls below 90%, take immediate CAPA before FDA asks. Remember – Every rejected batch is not just loss of money, it is loss of opportunity to supply medicine to patient.
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About the Author
Mahummed Asif is a experienced pharmaceutical Quality Assurance professional and publisher of Pharmashare. He has worked with leading Pharmaceutical organizations and has developed extensive expertise in Quality Assurance, deviation management, investigations, CAPA, QMS, Product Life Cycle Management, change control, risk management, validation, product complaints, product recalls, and regulatory compliance. He is passionate about sharing practical pharmaceutical knowledge with professionals, students, and quality practitioners across the industry.