Standard Operating Procedure for Layer Thickness Monitoring in Multi-Layer Tablets
| Department | Quality Control |
|---|---|
| SOP No. | SOP/TAB/134/2025 |
| Supersedes | SOP/TAB/134/2022 |
| Page No. | Page 1 of 6 |
| Issue Date | 01/03/2026 |
| Effective Date | 06/03/2026 |
| Review Date | 01/03/2027 |
1. Purpose
To define the procedure for monitoring the layer thickness of multi-layer tablets during production to ensure uniformity and meet the required specifications for tablet performance and quality.
2. Scope
This SOP applies to the monitoring of layer thickness in multi-layer tablets during the manufacturing process. It ensures that each layer of the tablet is within the specified thickness range, contributing to consistent tablet quality.
3. Responsibilities
- Quality Control (QC): Responsible for monitoring and measuring the layer thickness of multi-layer tablets during production, ensuring that the thickness meets the required specifications.
- Tablet Compression Operator: Responsible for ensuring that the compression process is carried out correctly and that layer thickness is maintained within the specified limits.
- Quality Assurance (QA): Ensures that the layer thickness monitoring procedure is followed and reviews the results for compliance with the specified standards.
4. Accountability
The QC Manager is accountable for ensuring that layer thickness measurements are taken correctly and consistently throughout
production. The QA Manager is responsible for reviewing the results and ensuring compliance with the required quality standards.
5. Procedure
5.1 Layer Thickness Measurement
- Measure the thickness of the tablet layers at regular intervals during the compression process.
- Use precision calipers or other appropriate measuring devices to measure the thickness of each layer in the multi-layer tablet. Each layer must be measured at multiple points around the tablet to ensure uniformity.
- Record the measurement of each layer separately, noting the average thickness and any variations.
- The thickness of each layer should be within the specified tolerance range, typically ± 0.05 mm, depending on the product specifications.
5.2 Sampling
- For every batch, collect a representative sample of tablets to measure the layer thickness. Typically, collect 10 tablets per batch to ensure accurate representation.
- For multi-layer tablets, measure both the individual layers and the overall tablet thickness to verify the correct formation of all layers.
- Ensure that the sample is taken from different locations (top, middle, and bottom of the batch) to evaluate consistency across the entire batch.
5.3 Monitoring Frequency
- Monitor the layer thickness at regular intervals during the compression process. This could be after every 100 tablets or at specific stages of production (e.g., after each layer is applied).
- If the layer thickness consistently falls within the specified tolerance, monitoring can be reduced to once every 500 tablets. However, if there is a variation in the results, increase the monitoring frequency to every 50 tablets.
5.4 Corrective Actions
- If the layer thickness falls outside the specified tolerance range, take corrective actions such as adjusting the compression force, modifying the filling volume, or altering the tablet press settings.
- After making adjustments, re-sample and re-test the tablets to ensure that the layer thickness is within specification.
- Document all corrective actions taken and the results of re-sampling in the batch record (Annexure-2).
5.5 Documentation
- Record the layer thickness measurements for each tablet sampled, including the average thickness and the individual layer measurements, in the batch record (Annexure-2).
- Document any deviations from the specified thickness range and the corrective actions taken in the deviation report (Annexure-1).
- Ensure that all records are signed, dated, and reviewed by QA for compliance with the required specifications.
5.6 Acceptance Criteria
- The thickness of each layer should fall within the specified tolerance limits, typically ± 0.05 mm, unless otherwise specified for a specific product.
- If the layer thickness exceeds the allowable tolerance, the batch may need to be rejected or reworked.
5.7 Post-Production Actions
- Once the layer thickness has been confirmed to meet specifications, proceed with the next steps of tablet processing, such as coating, drying, and packaging.
- Ensure that the equipment used for measuring layer thickness is calibrated regularly and maintained according to the preventive maintenance schedule.
6. Abbreviations
- SOP: Standard Operating Procedure
- GMP: Good Manufacturing Practice
- QC: Quality Control
- QA: Quality Assurance
- API: Active Pharmaceutical Ingredient
7. Documents
- Batch Record (Annexure-2)
- Deviation Report (Annexure-1)
8. References
- USP <1217> – Tablet Thickness and Uniformity Testing
- 21 CFR Part 211 – Current Good Manufacturing Practice for Finished Pharmaceuticals (US FDA)
- European Pharmacopoeia (EP) – Tablet Layer Specifications
9. SOP Version
Version: 2.0
10. Approval Section
| Prepared By | Checked By | Approved By | |
|---|---|---|---|
| Signature | |||
| Date | |||
| Name | |||
| Designation | |||
| Department |
11. Annexures
Annexure-1: Deviation Report
| Deviation Date | Batch Number | Deviation Description | Corrective Action | Responsible Person |
|---|---|---|---|---|
| 15/12/2025 | Batch 001 | Layer thickness exceeded tolerance limit | Adjusted compression force and granule size | John Doe |
Annexure-2: Batch Record
| Sample Number | Layer Thickness Result | Action Taken |
|---|---|---|
| Sample 1 | Pass (Layer thickness within tolerance) | Accepted |
Revision History:
| Revision Date | Revision No. | Revision Details | Reason for Revision | Approved By |
|---|---|---|---|---|
| 01/01/2024 | 1.0 | Initial Version | New SOP Creation | QA Head |
| 01/02/2025 | 2.0 | Updated layer thickness monitoring process | Improved quality standards | QA Head |