Standard Operating Procedure for Testing Thickness of Enteric Coating in Process
| Department | Tablet |
|---|---|
| SOP No. | SOP/TAB/160/2025 |
| Supersedes | SOP/TAB/160/2022 |
| Page No. | Page 1 of 6 |
| Issue Date | 01/03/2026 |
| Effective Date | 06/03/2026 |
| Review Date | 01/03/2027 |
1. Purpose
To establish the procedure for measuring and ensuring the correct thickness of the enteric coating applied to tablets during the production process.
2. Scope
This SOP applies to the measurement of enteric coating thickness on tablets during the coating process, ensuring that the tablets meet product specifications for uniformity and quality.
3. Responsibilities
- Quality Control (QC): Responsible for performing the thickness testing of the enteric coating on tablets, documenting results, and ensuring that the coating meets specified thickness standards.
- Production Operator: Responsible for ensuring that the tablet coating process is performed according to the batch record and notifying QC when tablets are ready for thickness testing.
- Quality Assurance (QA): Ensures that the coating thickness testing procedure is followed according to the SOP and reviews the documentation for compliance.
4. Accountability
The QC Manager is accountable for ensuring that the enteric coating thickness test is performed as required and that any deviations from the specification are properly addressed. The QA Manager ensures compliance with this SOP and approves corrective actions when necessary.
5. Procedure
5.1 Preparation for Thickness Testing
- Ensure that the enteric coating equipment is properly set up and calibrated before starting the coating process.
- Verify that the batch of tablets is ready for coating, with all required excipients and active ingredients in place.
- Ensure that the required tools and instruments for measuring coating thickness (e.g., micrometers or specialized coating thickness gauges) are available and calibrated.
- Confirm that the coating pan and drying system are operating within the specified parameters, such as temperature and airflow, to ensure uniform coating application.
5.2 Sampling of Tablets
- Take a representative sample of tablets from the batch after the enteric coating process has been completed. Typically, 5 to 10 tablets should be sampled for testing, or as per the batch record.
- Label the samples with batch information, date, and time of sampling to ensure traceability.
- Ensure that the tablets are at room temperature and have not undergone any further processing, such as packaging, before testing.
5.3 Measuring Coating Thickness
- Measure the thickness of the enteric coating on each tablet using an appropriate measuring instrument (e.g., micrometer, coating thickness gauge, or other methods as approved by QC).
- For manual measurement, select random areas on the tablet surface and record the thickness at these points. Ensure that the measurements are taken at multiple locations to confirm uniformity of the coating.
- For automated systems, ensure that the equipment is calibrated and functioning properly, and record the measurements from the system.
- Document the measured values in the batch record (Annexure-2) and calculate the average thickness for the sampled tablets.
5.4 Documentation of Results
- Record the measured thickness values, average thickness, and any deviations from the acceptable thickness range in the batch record (Annexure-2).
- If the measured thickness exceeds the specified limits, initiate a deviation report (Annexure-1) and investigate the cause of the variation.
- Ensure that all results are signed by the responsible QC personnel and reviewed by QA.
5.5 Corrective Actions for Coating Thickness Deviations
- If the coating thickness exceeds or falls short of the acceptable limits, investigate the cause of the deviation. Possible causes may include incorrect coating solution viscosity, inadequate pan speed, or improper application of the coating.
- Adjust the coating process parameters, such as the solution viscosity, spray rate, or pan speed, to bring the thickness back within specifications.
- Re-sample and re-test the batch to confirm that the coating thickness is now within the required range.
- Record all corrective actions in the deviation report and the batch record.
5.6 Acceptance Criteria
- The batch is considered acceptable if the measured coating thickness is within the predefined limits specified in the batch record (typically ±10% of the target thickness).
- If more than 2 tablets in the sample fail the thickness test, initiate a deviation report and further investigation into the root cause of the variation.
5.7 Post-Testing Actions
- If the batch passes the coating thickness test, proceed with the next step in the tablet manufacturing process, such as drying or packaging.
- If the batch fails, perform corrective actions, rework the batch if necessary, and re-test the tablets to ensure the coating meets the required specifications.
6. Abbreviations
- SOP: Standard Operating Procedure
- GMP: Good Manufacturing Practice
- QC: Quality Control
- QA: Quality Assurance
- CAPA: Corrective and Preventive Action
7. Documents
- Batch Record (Annexure-2)
- Deviation Report (Annexure-1)
8. References
- USP <701> – Tablet Coating Specifications
- 21 CFR Part 211 – Current Good Manufacturing Practice for Finished Pharmaceuticals (US FDA)
- European Pharmacopoeia (EP) – Tablet Manufacturing Guidelines
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 | Coating thickness exceeded the specified limits | Adjusted spray rate and recalibrated equipment | John Doe |
Annexure-2: Batch Record
| Sample Number | Coating Thickness | Acceptable Range | Tested By |
|---|---|---|---|
| Sample 1 | 350 µm | ±10% of target thickness | Jane Smith |
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 coating thickness testing method | Improved testing accuracy | QA Head |