Standard Operating Procedure for Preparing Gels with pH-Sensitive Drug Release Mechanism
| Department | Gel Manufacturing |
|---|---|
| SOP No. | SOP/GM/196/2025 |
| Supersedes | SOP/GM/196/2022 |
| Page No. | Page 1 of 14 |
| Issue Date | 10/06/2025 |
| Effective Date | 12/06/2025 |
| Review Date | 10/06/2027 |
1. Purpose
To define the standardized procedure for manufacturing gels that incorporate pH-sensitive drug release technology, ensuring accuracy, reproducibility, and compliance with regulatory standards.
2. Scope
This SOP applies to the formulation, compounding, and filling of gels exhibiting pH-responsive drug release characteristics, specifically within the Gel Manufacturing Department.
3. Responsibilities
- Formulation Scientist: Designs the pH-responsive gel matrix and approves excipient compatibility.
- Production Chemist: Ensures strict adherence to process parameters and batch instructions.
- QA Executive: Verifies in-process controls and reviews batch records.
4. Accountability
Head – Manufacturing is accountable for the overall
implementation, control, and review of the procedure.
5. Procedure
5.1 Material and Equipment Preparation
- Review the batch manufacturing record (BMR) and pH-specific formulation protocol.
- Verify availability and status of all raw materials including polymers like Carbopol, Eudragit, or HPMC derivatives.
- Calibrate pH meters and check buffer solutions used in testing.
- Clean and prepare mixing vessels, agitators, and filling machines as per SOP/GM/073/2025.
5.2 pH-Sensitive Matrix Formulation
- Dissolve polymeric base in purified water under continuous stirring at controlled temperature.
- Add pH-sensitive drug compound ensuring full dispersion; use a homogenizer if needed.
- Adjust gel viscosity and transparency by titration with acid/base until optimal pH range is achieved (typically pH 5.5–6.8).
- Perform in-process pH testing and record results (refer Annexure-2).
5.3 Drug Incorporation and Final Homogenization
- Add active pharmaceutical ingredient (API) dissolved or suspended in pre-filtered vehicle.
- Mix until uniform distribution is achieved and test for homogeneity (refer Annexure-3).
- Add preservatives, stabilizers, or pH indicators if applicable.
See also Gel Manufacturing: SOP for Disinfection of Gel Manufacturing Area After Maintenance - V 2.0
5.4 Filling and Packaging
- Filter gel through 80–120 mesh if required to ensure consistency.
- Transfer into filling machine and fill into laminated or aluminum tubes under controlled conditions.
- Seal, crimp, and print batch details. Samples for QC testing must be retained (see Annexure-4).
5.5 In-Process and QC Tests
- Appearance, pH, viscosity, drug content uniformity, microbial limits, and pH-triggered release profiling.
- Ensure pH-triggered release profile is verified through in-vitro dissolution studies.
5.6 Documentation
- Complete batch manufacturing and control records.
- Attach calibration certificates of pH meters and any deviation reports.
6. Abbreviations
- API: Active Pharmaceutical Ingredient
- BMR: Batch Manufacturing Record
- HPMC: Hydroxypropyl Methylcellulose
- QA: Quality Assurance
7. Documents
- Batch Manufacturing Record – Annexure-1
- pH Adjustment Log – Annexure-2
- Homogeneity Test Record – Annexure-3
- Filling Activity Log – Annexure-4
- pH-Responsive Drug Release Profile – Annexure-5
8. References
- ICH Q8: Pharmaceutical Development
- ICH Q6A: Specifications – Test Procedures and Acceptance Criteria
- Schedule M: Good Manufacturing Practices
9. SOP Version
Version: 2.0
10. Approval Section
| Prepared By | Checked By | Approved By | |
|---|---|---|---|
| Signature | |||
| Date | |||
| Name | |||
| Designation | Jr. Production Chemist | QA Executive | Head – Manufacturing |
| Department | Gel Manufacturing | Quality Assurance | Manufacturing |
11. Annexures
Annexure-1: Batch Manufacturing Record
| Batch No. | Product Name | Date | Formulator | QA Reviewer |
|---|---|---|---|---|
Annexure-2: pH Adjustment Log
| Time | Observed pH | Adjusted To | Base/Acid Used | Done By |
|---|---|---|---|---|
Annexure-3: Homogeneity Test Record
| Sample Point | Drug Content (%) | Standard Range | Result | Checked By |
|---|---|---|---|---|
| Top | ±5% | |||
| Middle | ||||
| Bottom |
Annexure-4: Filling Activity Log
| Filling Line No. | Date | Operator | Yield (%) | Remarks |
|---|---|---|---|---|
Annexure-5: pH-Responsive Drug Release Profile
| pH | Time (min) | % Drug Released | Acceptance Criteria | QC Signature |
|---|---|---|---|---|
| 4.5 | 60 | <10% | ||
| 6.8 | 60 | >85% |
Revision History
| Revision Date | Revision No. | Change Description | Reason | Approved By |
|---|---|---|---|---|
| 01/06/2022 | 1.0 | Initial issue | New product line | QA Head |
| 10/06/2025 | 2.0 | Revised with enhanced pH release testing | Annual revision | QA Head |