Standard Operating Procedure for Optimizing Coating Suspension Viscosity
| Department | Tablet |
|---|---|
| SOP No. | SOP/TAB/034/2025 |
| Supersedes | SOP/TAB/034/2022 |
| Page No. | Page 1 of 6 |
| Issue Date | 28/07/2025 |
| Effective Date | 02/08/2025 |
| Review Date | 28/07/2026 |
1. Purpose
This SOP defines the procedure for optimizing the coating suspension viscosity during tablet coating processes. Optimizing the viscosity ensures uniform coating application, prevents coating defects, and improves tablet quality by controlling the flow characteristics of the coating suspension.
2. Scope
This SOP applies to the tablet coating process and focuses on optimizing the coating suspension viscosity. The procedure covers the preparation, mixing, and adjustments required to achieve the desired viscosity for the coating solution used in the production of tablets.
3. Responsibilities
- Manufacturing Personnel: Responsible for preparing the coating suspension according to the specified formulation and for making adjustments to viscosity as needed during production.
- Quality Control (QC): Responsible for testing the viscosity of the coating suspension at various stages to ensure that it meets the required specifications.
- Quality Assurance (QA): Ensures that the viscosity optimization process is conducted in accordance with this SOP and that all documentation is properly maintained for compliance and audit purposes.
- Process Engineers: Responsible for providing guidance on the appropriate equipment settings and formulation adjustments to optimize the coating suspension viscosity.
4. Accountability
The Production Manager is accountable for ensuring the correct preparation and optimization of the coating suspension. The QA Manager is responsible for ensuring that the process follows this SOP and that all quality checks are performed properly.
5. Procedure
5.1 Coating Suspension Preparation
- Prepare the coating suspension by mixing the specified ingredients, such as the film-forming agent, solvents, plasticizers, and other excipients, according to the formulation.
- Ensure that the ingredients are mixed thoroughly to avoid clumping or uneven dispersion of materials.
- Use a high-shear mixer or other suitable equipment to ensure uniform mixing of the coating suspension components.
- Check the temperature of the suspension during mixing to ensure it is within the recommended range for the ingredients used.
5.2 Initial Viscosity Measurement
- After the suspension is prepared, measure the viscosity using a viscometer or rheometer to determine the initial viscosity of the coating solution.
- Record the viscosity value in the viscosity log (Annexure-1) and compare it to the desired range as per the product specifications.
- If the viscosity is outside the acceptable range, proceed with the adjustment process outlined in section 5.3.
5.3 Adjusting Coating Suspension Viscosity
- If the viscosity is too high or too low, adjust the coating suspension by adding a suitable solvent or thickener, depending on whether the suspension needs to be thinned or thickened.
- For thinning the suspension, add the specified solvent in small increments while mixing continuously. Monitor the viscosity after each addition to avoid over-thinning.
- If the suspension needs thickening, add the appropriate thickening agent or binder, mixing thoroughly to ensure it dissolves completely and evenly in the solution.
- Adjust the mixing speed, temperature, and time as necessary to achieve the desired viscosity.
- After each adjustment, measure the viscosity again to ensure that it is within the desired range and that the coating suspension is consistent.
- Record all viscosity adjustments and final viscosity values in the batch record (Annexure-2).
5.4 Monitoring Viscosity During Production
- During tablet coating, continuously monitor the viscosity of the coating suspension to ensure that it remains within the acceptable range.
- Use in-line viscosity sensors or take periodic samples to measure viscosity during the coating process.
- If any fluctuations in viscosity are detected, stop the coating process and make necessary adjustments as outlined in section 5.3.
- Ensure that the coating process is stopped if viscosity exceeds the upper limit or drops below the lower limit, as this could lead to coating defects such as uneven distribution or poor adhesion.
5.5 Post-Coating Suspension Testing
- Once the coating process is completed, measure the final viscosity of the coating suspension to ensure that it matches the target viscosity.
- Document the final viscosity in the batch record (Annexure-2) and include any corrective actions taken during the coating process if viscosity was adjusted.
- Ensure that all unused coating suspension is properly stored or disposed of according to the waste management SOP.
5.6 Documentation and Record-Keeping
- All viscosity measurements, adjustments, and final results must be documented in the viscosity log (Annexure-1) and batch record (Annexure-2).
- Any deviations from the desired viscosity range must be recorded, along with the corrective actions taken.
- Ensure that all records are signed off by the responsible personnel and are retained 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
- Viscosity Log (Annexure-1)
- Batch Record (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: Viscosity Log
| Batch Number | Tablet Type | Viscosity Initial (cP) | Viscosity Adjusted (cP) | Remarks |
|---|---|---|---|---|
| Batch 001 | Tablet A | 350 | 360 | Added solvent to achieve optimal viscosity |
| Batch 002 | Tablet B | 340 | 330 | Added thickener to adjust viscosity |
Annexure-2: Batch Record
| Batch Number | Tablet Type | Coating Suspension Viscosity | Final Tablet Quality | Remarks |
|---|---|---|---|---|
| Batch 001 | Tablet A | 360 cP | Pass | Coating applied successfully |
| Batch 002 | Tablet B | 330 cP | Pass | Adjustment made to viscosity during production |
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 Viscosity Adjustment Procedures | Improved Adjustment Techniques | QA Head |