The QC Manager is accountable for ensuring that viscosity testing is conducted accurately and in accordance with this SOP. The Production Supervisor is responsible for ensuring that representative samples are collected for viscosity testing. The QA Manager ensures overall compliance with GMP and regulatory requirements.

5. Procedure

5.1 Pre-Test Preparation

1. Ensure that the viscometer is calibrated according to the manufacturer’s guidelines before performing any viscosity testing. Use calibration standards and check the accuracy of the instrument regularly.
2. Review the batch record to determine the appropriate stage for viscosity testing, such as after formulation, after mixing, or before filling. Ensure that the sampling plan specifies the necessary quantity of the sample.
3. Ensure that the test environment is clean and free from contamination, and prepare all necessary tools and equipment, including viscometers, sampling containers, and labeling materials.
4. Verify that all personnel performing the viscosity testing are trained and familiar with the SOP and safety procedures for handling the equipment.

5.2 Sample Collection

1. Collect a representative sample from the batch at the designated stage (e.g., after mixing). Ensure that the sample is mixed thoroughly before collecting to prevent any inconsistencies in the viscosity measurement.
2. Label the sample container with the batch number, sampling date, and sampling point (e.g., post-mixing, pre-filling) for proper identification during testing.
3. If necessary, store the sample under appropriate conditions (e.g., refrigerated or at room temperature) until the test is conducted to ensure that the viscosity measurement is accurate and reflects the formulation’s intended properties.

5.3 Viscosity Testing Procedure

1. Set up the viscometer according to the manufacturer’s instructions and ensure that the measurement parameters (e.g., rotational speed, spindle type) are appropriate for the cream sample being tested.
2. Place the cream sample into the viscometer cup or container, ensuring that it is filled to the required level. Avoid air bubbles or contamination in the sample.
3. Start the viscometer and allow it to run for a sufficient period to measure the viscosity of the sample. Record the viscosity reading after it stabilizes, ensuring that the reading is within the specified range.
4. If the viscosity value is outside the acceptable range, repeat the test with a new sample and ensure that all factors, such as temperature and sample consistency, are controlled during the measurement.
5. Record the viscosity value, test conditions (e.g., temperature, spindle speed), and any deviations observed in the Viscosity Testing Log (Annexure-1).

5.4 Interpretation of Results

1. Compare the viscosity values obtained to the product’s defined specifications, which are based on the intended texture and spreadability of the cream formulation. The viscosity should be consistent with the product’s intended use.
2. If the viscosity is within the acceptable range, mark the test as “Pass” in the Viscosity Testing Log (Annexure-1). If the viscosity falls outside the defined range, mark the test as “Fail” and investigate the cause of the deviation.
3. Common causes for viscosity deviations may include improper formulation, incorrect mixing speeds, or ingredient inconsistencies. Investigate and document any corrective actions taken.

5.5 Post-Test Activities

1. Document all test results, including the viscosity reading, batch number, sampling date, and any corrective actions taken, in the Viscosity Testing Log (Annexure-1).
2. If the test result is outside the acceptable range, initiate corrective actions such as adjusting the formulation or mixing conditions. Re-test the sample after making any adjustments to confirm that the viscosity is within the specified range.
3. Review the viscosity results and the associated documentation for accuracy and completeness. Ensure that the test results are reviewed and approved by the QA team.

5.6 Documentation and Record-Keeping

1. Ensure that all records related to viscosity testing are complete, accurate, and stored securely. This includes the Viscosity 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 required by regulatory guidelines.
3. Ensure that records are reviewed and approved by the Quality Assurance team to verify compliance with GMP standards and regulatory requirements.

6. Abbreviations

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

7. Documents

1. Annexure-1: Viscosity 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 Viscosity Measurement Instruments

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 Testing Log

Batch Number	Sample ID	Sampling Date	Viscosity (cP)	Operator
12345	S-001	21/01/2026	750 cP	John Doe

Annexure-2: Deviation Log

Deviation Date	Batch Number	Deviation Description	Corrective Action Taken	Operator
21/01/2026	12345	Viscosity below range	Adjusted formulation 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