Standard Operating Procedure for Rheological Characterization in Gel Formulations
| Department | Gel Manufacturing |
|---|---|
| SOP No. | SOP/GM/017/2025 |
| Supersedes | SOP/GM/017/2022 |
| Page No. | Page 1 of 12 |
| Issue Date | 02/06/2025 |
| Effective Date | 04/06/2025 |
| Review Date | 02/06/2026 |
1. Purpose
To establish a standardized procedure for conducting rheological evaluations of gel formulations, ensuring consistent flow behavior, texture, and product quality across batches.
2. Scope
This SOP applies to all batches of semi-solid gel formulations produced in the Gel Manufacturing Department where rheological evaluation is part of
product release and development characterization.
3. Responsibilities
- QC Analysts: Perform rheological tests as per the defined protocol.
- QA Personnel: Verify results, review documentation, and ensure compliance with specifications.
- Formulation Scientists: Design rheological study methods and analyze data trends.
4. Accountability
Department Head – Gel Manufacturing and Head – Quality Control shall be accountable for implementation, review, and periodic training related to rheological evaluation procedures.
5. Procedure
5.1 Instrumentation and Calibration
- Use a Brookfield Viscometer or Rheometer with appropriate spindles and temperature control system.
- Ensure instrument calibration is within valid range using certified calibration fluids (Annexure-1).
5.2 Sample Preparation
- Gently homogenize the gel sample using a sterile spatula to ensure uniformity before testing.
- Fill the sample container without entrapping air bubbles.
5.3 Testing Conditions
- Set the test temperature (e.g., 25°C ± 1°C) using the instrument’s temperature control.
- Select the appropriate spindle (e.g., Spindle No. 64) and RPM as per the test protocol.
5.4 Parameters to Measure
- Viscosity: Record in centipoise (cP) at various RPMs.
- Flow Behavior: Assess thixotropy, pseudoplasticity, or Newtonian behavior.
- Yield Stress: Use stress-controlled measurements if applicable.
5.5 Data Recording and Interpretation
- Record time, temperature, RPM, spindle type, and viscosity in a Rheology Logbook (Annexure-2).
- Plot flow curves to assess structural breakdown and recovery trends.
- Compare with product specification range approved in the Master Formula Record (MFR).
5.6 Cleaning and Maintenance
- Clean the spindle and sample holder with 70% IPA or a validated cleaning agent.
- Log the cleaning details in the Instrument Usage Log (Annexure-3).
6. Abbreviations
- SOP: Standard Operating Procedure
- QC: Quality Control
- QA: Quality Assurance
- MFR: Master Formula Record
7. Documents
- Rheological Instrument Calibration Record – Annexure-1
- Rheology Test Logbook – Annexure-2
- Instrument Cleaning and Maintenance Log – Annexure-3
8. References
- USP <1092> – The Rheological Properties of Semisolids
- ICH Q6A – Specifications: Test Procedures and Acceptance Criteria for New Drug Substances and Products
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: Rheological Instrument Calibration Record
| Fluid Used | Expected Viscosity | Observed Viscosity | Status |
|---|---|---|---|
| Calibration Fluid A | 1000 cP | 995 cP | Pass |
Annexure-2: Rheology Test Logbook
| Date | Sample Code | Viscosity | Spindle | RPM | Remarks |
|---|---|---|---|---|---|
| 01/06/2025 | GLP-017 | 12500 cP | 64 | 20 | Within Spec |
Annexure-3: Instrument Cleaning and Maintenance Log
| Date | Cleaning Agent | Performed By | Remarks |
|---|---|---|---|
| 01/06/2025 | 70% IPA | Technician A | Cleaned post-test |
Revision History:
| Revision Date | Revision No. | Details | Reason | Approved By |
|---|---|---|---|---|
| 01/06/2022 | 1.0 | Initial Issue | New SOP | QA Head |
| 02/06/2025 | 2.0 | Updated with flow behavior analysis | Annual Review | QA Head |