Manager is accountable for overseeing all rheological analysis activities and ensuring accurate results. The Production Supervisor is responsible for ensuring proper sampling at the appropriate stages of production. The QA Manager ensures that the SOP is followed and that all records are reviewed for compliance.

5. Procedure

5.1 Pre-Test Preparation

1. Ensure that the rheometer or viscometer is calibrated according to the manufacturer’s specifications before conducting any tests. Perform calibration checks using standard viscosity fluids to verify accuracy.
2. Prepare all necessary materials and equipment for the test, including clean containers, testing utensils, and the sample to be analyzed.
3. Review the batch record to confirm the appropriate sampling stage for rheological testing. Typically, samples should be taken after mixing, but before packaging, to ensure that the cream has had sufficient time to develop its final properties.
4. Ensure that the sample is at the correct temperature, as temperature can significantly affect rheological properties. If required, adjust the sample temperature to room temperature before testing.

5.2 Sample Collection

1. Collect a representative sample from the cream formulation at the specified stage of production (e.g., after mixing or before filling).
2. Ensure that the sample is homogeneous and free from air bubbles or contamination.
3. Label the sample with the appropriate batch number, sampling date, and sampling point (e.g., post-mixing, pre-filling) to ensure traceability.
4. Store the sample in a clean, sealed container until it is ready to be analyzed. If needed, ensure that the sample is stored under temperature-controlled conditions until testing.

5.3 Rheological Testing Procedure

1. Set up the rheometer or viscometer according to the manufacturer’s instructions. Select the appropriate spindle and measurement settings for the sample, ensuring the test parameters (e.g., shear rate, rotational speed) are suitable for the cream formulation.
2. Place the cream sample into the rheometer’s measuring cup or container, ensuring that the sample is fully immersed and free from air pockets or contamination.
3. Start the rheometer and allow it to run for the required period. Record the flow curves, yield stress, viscosity, and any other relevant parameters as per the testing protocol.
4. If the sample has a thixotropic or shear-thinning behavior, conduct measurements at multiple shear rates to assess how the cream’s viscosity changes under stress.
5. Once the test is complete, record all results, including any deviations from the expected flow behavior or rheological properties, in the Rheological Testing Log (Annexure-1).

5.4 Interpretation of Results

1. Compare the rheological data with the product’s defined specifications, which may include acceptable viscosity ranges, yield stress, and consistency parameters for the cream formulation.
2. If the rheological results meet the specifications, mark the test as “Pass” in the Rheological Testing Log (Annexure-1).
3. If the results are outside the specified range, investigate the cause of the deviation, which may include formulation issues, improper mixing, or incorrect testing procedures.
4. If necessary, adjust the formulation or manufacturing process and repeat the testing until the cream meets the specified rheological properties.

5.5 Post-Test Activities

1. Document all rheological test results, including the batch number, sample ID, shear rate, viscosity, yield stress, and any corrective actions taken, in the Rheological Testing Log (Annexure-1).
2. If corrective actions are required, ensure that they are documented and communicated to the production team. Re-test the formulation after implementing changes.
3. Ensure that all records are reviewed by the QA team for accuracy and completeness.

5.6 Documentation and Record-Keeping

1. Ensure that all rheological testing records are complete, accurate, and stored securely. This includes the Rheological Testing Log (Annexure-1) and any deviation logs for failed tests (Annexure-2).
2. Retain all records for a minimum of two years or as per regulatory requirements.
3. Ensure that records are reviewed by the Quality Assurance team to verify compliance with GMP standards and regulatory guidelines.

6. Abbreviations

• GMP: Good Manufacturing Practices
• QC: Quality Control
• QA: Quality Assurance
• PPE: Personal Protective Equipment

7. Documents

1. Annexure-1: Rheological Testing Log
2. Annexure-2: Deviation Log

8. References

• Good Manufacturing Practices (GMP) Guidelines – 21 CFR Part 211
• International Conference on Harmonisation (ICH) Q7 – Good Manufacturing Practice for Active Pharmaceutical Ingredients
• Manufacturer’s Manual for Rheometers

9. SOP Version

Version: 2.0

10. Approval Section

	Prepared By	Checked By	Approved By
Signature
Date
Name
Designation
Department

11. Annexures

Annexure-1: Rheological Testing Log

Batch Number	Sample ID	Sampling Date	Viscosity (cP)	Yield Stress	Operator
12345	S-001	21/01/2026	500 cP	5.0 Pa	John Doe

Annexure-2: Deviation Log

Deviation Date	Batch Number	Deviation Description	Corrective Action Taken	Operator
21/01/2026	12345	Viscosity outside range	Adjusted mixing time and re-tested	Jane Smith

Revision History:

Revision Date	Revision No.	Revision Details	Reason for Revision	Approved By
01/03/2024	1.0	Initial Version	New SOP Creation	QA Head
01/03/2025	2.0	Format Revision and Updates	Standardization of Document	QA Head