Standard Operating Procedure for Spray Coating Techniques for Film Coating
| Department | Tablet |
|---|---|
| SOP No. | SOP/TAB/021/2025 |
| Supersedes | SOP/TAB/021/2022 |
| Page No. | Page 1 of 8 |
| Issue Date | 24/05/2025 |
| Effective Date | 29/05/2025 |
| Review Date | 24/05/2026 |
1. Purpose
This SOP defines the spray coating techniques used for film coating tablets, ensuring uniform application of the coating, optimal coating thickness, and consistent quality throughout production.
2. Scope
This SOP applies to the film coating process for tablets using spray coating techniques, including equipment setup, process parameters, and quality control checks during the coating process.
3. Responsibilities
- Manufacturing Personnel: Responsible for preparing the equipment, monitoring the coating process, and ensuring that tablets meet quality standards.
- Quality Control (QC): Conducts in-process checks to ensure the coating is uniform, within thickness specifications, and free from defects.
- Quality Assurance (QA): Ensures that the spray coating process follows this SOP and that all records are maintained for compliance and traceability.
4. Accountability
The Production Manager is accountable for ensuring the spray coating process is conducted per this SOP. The QA Manager is responsible for reviewing and approving the coating process to ensure compliance with the quality standards and regulatory requirements.
5. Procedure
5.1 Equipment Setup
- Ensure that the film coating machine, spray guns, and drying units are clean and free of contamination from previous batches, as per the cleaning SOP.
- Verify that the equipment is properly calibrated for the required coating parameters, including spray pressure, atomization, and drying temperature.
- Ensure that the coating pan is correctly aligned, and the coating solution is properly prepared and filtered to avoid particle contamination during spraying.
- Set up the required spray nozzle size and air pressure according to the tablet size and coating material to achieve the desired coating thickness and uniformity.
- Ensure the required level of humidity and temperature in the coating environment to support the drying process and prevent excess moisture retention.
5.2 Preparing the Coating Solution
- Prepare the coating solution by dissolving the coating materials (e.g., film-forming agents, plasticizers, colorants) in the appropriate solvent or water.
- Ensure the solution is properly mixed to prevent the formation of lumps or undissolved particles, which could lead to uneven coating.
- Filter the coating solution before use to remove any solid particles that may block the spray nozzle or cause coating defects.
- Check the viscosity of the coating solution to ensure it is suitable for the spray coating process. Adjust the viscosity if necessary by adding solvent or water.
5.3 Coating Process
- Load the core tablets into the film coating pan and start the pan rotation at the specified speed to ensure uniform tablet movement.
- Activate the spray system, ensuring that the spray pattern is uniform and fine mist is applied to the tablets.
- Adjust the spray pressure and atomization to maintain consistent spray coverage across the tablet surface without over-spraying or causing clogging of the nozzle.
- Spray the coating solution evenly over the rotating tablets, ensuring that each tablet receives a uniform layer of coating. Ensure that the spray application is consistent and that no pooling or uneven coverage occurs.
- Periodically stop the machine to visually inspect the coating process, checking for uniformity in color and thickness.
5.4 Drying Process
- Ensure that the drying system (e.g., drying air or hot air blower) is set to the appropriate temperature and airflow to dry the coating without causing cracking or distortion of the tablets.
- Dry the coated tablets after each spraying cycle to ensure that the coating adheres properly and does not cause tablet agglomeration.
- Monitor the temperature and humidity of the drying air to ensure it is within the optimal range to avoid excessive moisture or uneven drying.
- Continue the spray and drying process until the required coating thickness is achieved, as defined by the product specifications.
5.5 In-Process Quality Control
- At regular intervals, collect samples of coated tablets to test for uniformity in coating thickness, weight, and appearance.
- Measure the coating thickness using a micrometer or appropriate coating thickness gauge, ensuring that it meets the specified limits (typically between 2-5% of tablet weight).
- Perform visual inspections for coating defects, such as uneven color, cracks, or peeling, which could indicate issues with the spraying or drying process.
- Check the tablet surface for any sticking or capping that could be caused by excessive moisture or improper drying.
- Record all quality control data, including coating thickness and appearance, in the batch record (Annexure-1).
5.6 Adjustments and Corrections
- If any defects are found during the in-process inspection (e.g., uneven coating or peeling), adjust the spray settings, such as air pressure, nozzle size, or spray speed, to correct the issue.
- If the coating thickness is inconsistent, adjust the spray time or the number of spray cycles to ensure uniform coverage.
- Monitor the drying temperature and humidity closely to avoid over-drying or under-drying, which could affect the final coating quality.
- Document any adjustments made during the process and ensure corrective actions are reviewed and approved by QA personnel.
5.7 Final Inspection
- Once the desired coating thickness has been achieved, conduct a final inspection of the coated tablets to ensure they meet all quality criteria for uniformity, appearance, and tablet integrity.
- Perform a dissolution test to ensure that the film coating does not interfere with the release profile of the tablet and that the tablet performs according to the product specifications.
- Check the tablets for any visible defects, such as chipping, cracking, or irregularities in the coating layer.
- If any defects are found, isolate the affected tablets for further investigation or rework according to SOP.
5.8 Packaging and Storage
- Once the tablets pass the final inspection, package them in suitable containers to protect them from environmental factors such as moisture, light, and air that could damage the coating.
- Ensure that the packaging material is appropriate for coated tablets, providing adequate protection and maintaining tablet integrity during transportation and storage.
- Store the tablets in a controlled environment with proper temperature and humidity settings to maintain the stability of the coating and the active ingredients.
5.9 Documentation and Record-Keeping
- Document all spray coating parameters, including spray pressure, atomization settings, coating solution composition, and drying conditions, in the batch record (Annexure-2).
- Ensure that any deviations or corrective actions taken during the process are properly recorded and reviewed by QA to ensure compliance with regulatory requirements.
- Maintain records of all in-process quality control checks, including coating thickness, weight, and appearance, for future reference and audits.
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)
- Coating Process Log (Annexure-2)
8. References
- 21 CFR Part 211 – Current Good Manufacturing Practice for Finished Pharmaceuticals (US FDA)
- EU GMP Guidelines Part I – Basic Requirements for Medicinal Products
- ICH Q7 – Good Manufacturing Practice Guide for Active Pharmaceutical Ingredients
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 Type | Compression Force | Coating Solution | Coating Thickness | Remarks |
|---|---|---|---|---|---|
| Batch 001 | Tablet A | 500 N | Film Coating Solution | 2.5% | Within specifications |
| Batch 002 | Tablet B | 520 N | Film Coating Solution | 2.8% | Minor deviation, resolved |
Annexure-2: Coating Process Log
| Batch Number | Tablet Type | Spray Pressure | Atomization | Drying Temperature | Remarks |
|---|---|---|---|---|---|
| Batch 001 | Tablet A | 3 bar | Fine mist | 50°C | Within specifications |
| Batch 002 | Tablet B | 3.5 bar | Medium mist | 52°C | Adjusted for coating thickness |
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 Spray Coating Process | Optimization of Coating Process | QA Head |