Standard Operating Procedure for Coating Thickness Measurement in Sugar-Coated Tablets
| Department | Tablet |
|---|---|
| SOP No. | SOP/TAB/080/2025 |
| Supersedes | SOP/TAB/080/2022 |
| Page No. | Page 1 of 6 |
| Issue Date | 01/03/2026 |
| Effective Date | 06/03/2026 |
| Review Date | 01/03/2027 |
1. Purpose
To provide a standardized procedure for measuring the coating thickness of sugar-coated tablets, ensuring that the coating is within the required specifications for uniformity and quality.
2. Scope
This SOP applies to the measurement of coating thickness in sugar-coated tablets to ensure that the coating process meets the specified standards and ensures proper product quality.
3. Responsibilities
- Manufacturing Personnel: Responsible for providing sugar-coated tablets for coating thickness measurement and ensuring they are free from defects.
- Quality Control (QC): Responsible for performing the coating thickness measurement, recording the results, and ensuring the coating meets the specified thickness limits.
- Quality Assurance (QA): Ensures that the coating thickness measurement procedure is followed and reviews the results for batch approval and release.
4. Accountability
The QC Manager is accountable for ensuring that the coating thickness measurement is carried out in compliance with this SOP and for reporting the results. The QA Manager is responsible for reviewing the results and approving the batch for release.
5. Procedure
5.1 Sample Collection
- Collect a representative sample of sugar-coated tablets from the batch as specified in the batch record.
- The sample should consist of 6 tablets (or as specified in the batch record or pharmacopeial guidelines).
- Ensure that the tablets are free from defects such as cracks, chips, or visible contamination.
- Label the sample appropriately for identification during testing.
5.2 Selection of Coating Measurement Method
- Choose the appropriate method for measuring coating thickness, typically using a micrometer, a caliper, or a coating thickness gauge.
- Ensure that the measurement tool is clean, calibrated, and functioning properly before use.
5.3 Coating Thickness Measurement
- For each tablet, measure the coating thickness at multiple points (typically at 3 different locations on each tablet: top, middle, and bottom).
- Ensure that the measurements are taken at consistent points on each tablet and that they are measured perpendicular to the surface of the tablet.
- Record the thickness measurements in the batch record (Annexure-1) for each tablet.
5.4 Data Analysis and Calculation
- Calculate the average coating thickness based on the measurements from the 6 tablets.
- Ensure that the average coating thickness falls within the acceptable range specified in the batch record or pharmacopeial guidelines (e.g., ±10% of the target coating thickness).
- If any tablet’s coating thickness falls outside the acceptable range, document the findings in the batch record and initiate an investigation (Annexure-2).
5.5 Coating Acceptance Criteria
- Ensure that the average coating thickness and individual tablet thicknesses meet the specified coating thickness requirements.
- If any tablet fails to meet the coating thickness specifications, the batch should be investigated, and corrective actions should be documented.
5.6 Documentation and Record-Keeping
- Document the coating thickness measurements for each tablet, including the individual tablet thicknesses and the average coating thickness, in the batch record (Annexure-1).
- Record any deviations from the coating thickness specifications in the deviation report (Annexure-2), along with the corrective actions taken.
- Ensure all records are signed, dated, and stored according to the company’s record retention policy for future audits and inspections.
5.7 Post-Test Cleanup
- Clean the measurement tools (micrometer, caliper, or coating thickness gauge) according to the manufacturer’s guidelines and the company’s cleaning SOP.
- Ensure that all equipment is properly stored and maintained in good working condition.
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-1)
- Deviation Report (Annexure-2)
8. References
- USP <1168> – Coating Thickness Test
- 21 CFR Part 211 – Current Good Manufacturing Practice for Finished Pharmaceuticals (US FDA)
- European Pharmacopoeia (EP) – Coating Thickness Measurement
9. SOP Version
Version: 2.0
10. Approval Section
| Prepared By | Checked By | Approved By | |
|---|---|---|---|
| Signature | |||
| Date | |||
| Name | |||
| Designation | |||
| Department |
11. Annexures
Annexure-1: Batch Record
| Batch Number | Tablet Sample | Coating Thickness (mm) | Average Coating Thickness (mm) |
|---|---|---|---|
| Batch 001 | 6 tablets | 0.15 | 0.14 |
Annexure-2: Deviation Report
| Deviation Date | Batch Number | Deviation Description | Corrective Action | Responsible Person |
|---|---|---|---|---|
| 10/12/2025 | Batch 001 | Coating thickness variation | Re-adjusted coating process | John Doe |
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 Process Parameters | Refined measurement methods | QA Head |