Standard Operating Procedure for Rheological Properties Analysis in Creams

Department	Creams
SOP No.	SOP/CRM/036/2025
Supersedes	SOP/CRM/036/2022
Page No.	Page 1 of 6
Issue Date	24/08/2025
Effective Date	29/08/2025
Review Date	24/08/2026

1. Purpose

The purpose of this Standard Operating Procedure (SOP) is to define the process for analyzing the rheological properties of cream formulations. Rheological properties such as viscosity, flow behavior, and elasticity are key indicators of product performance, stability, and texture. This SOP ensures that the cream formulations meet the required rheological specifications for both functional and sensory attributes.

2. Scope

This SOP applies to all cream formulations developed in the Creams Department. It includes the methods and techniques used to evaluate the rheological properties of the creams to ensure consistency, quality, and usability of the final product.

3. Responsibilities

• Formulation Development Team: Responsible for selecting ingredients that achieve the desired rheological properties and ensuring proper formulation techniques.
• Quality Control (QC): Responsible for conducting rheological tests on cream formulations to measure and assess viscosity, flow behavior, and elasticity according to the specified standards.
• Quality Assurance (QA): Ensures compliance with this SOP, reviewing the rheological testing results and approving the formulations for commercial production.
• Production Team: Implements the rheological testing procedure during manufacturing and ensures that the production process results in the desired rheological properties in the final cream product.

4. Accountability

The Head of Creams Manufacturing is responsible for overseeing the rheological properties analysis process. The QA Manager is accountable for ensuring that all rheological testing is conducted according to this SOP and the results are properly documented and reviewed.

5. Procedure

5.1 Selection of Rheological Testing Equipment

1. Select an appropriate rheometer or viscometer for analyzing the rheological properties of the cream formulation. Common equipment includes:
   • Brookfield Viscometer: Measures viscosity and flow behavior.
   • Rheometer: Measures a range of rheological properties such as shear stress, viscosity, and yield point.
   • Texture Analyzer: Measures the cream’s spreadability, firmness, and yield stress.
2. Ensure that the equipment is calibrated before use, following the manufacturer’s instructions for proper calibration and maintenance.

5.2 Sample Preparation

1. Prepare the cream sample according to the formulation specifications. Ensure that the sample is mixed uniformly and represents the final product batch.
2. If necessary, allow the cream sample to equilibrate at room temperature to avoid temperature-induced viscosity changes before testing.
3. Ensure that the sample size is appropriate for the rheometer or viscometer, as per the equipment’s specifications.

5.3 Conducting Rheological Tests

1. Perform the following key rheological tests:
   • Viscosity Measurement: Measure the viscosity of the cream under controlled shear rates to evaluate its resistance to flow. Record the viscosity at different shear rates to determine whether the cream exhibits shear-thinning or shear-thickening behavior.
   • Flow Behavior: Analyze the cream’s flow properties to determine its flow curve, which is essential for understanding how the cream behaves under application conditions (e.g., spreading on the skin).
   • Elasticity and Yield Stress: Measure the cream’s elasticity, which reflects its ability to return to its original form after deformation. Yield stress indicates the force required to initiate flow.
2. Conduct the tests according to the manufacturer’s instructions and ensure that the data is collected under standardized conditions to maintain consistency across batches.
3. Document all test parameters, including test type, equipment settings, and testing conditions, in the batch record.

5.4 Analyzing the Results

1. Analyze the results to assess the rheological behavior of the cream. Compare the viscosity values, flow curves, and elasticity measurements against the target specifications.
2. If the cream does not meet the required rheological properties, make adjustments to the formulation or processing parameters (e.g., adding thickeners, adjusting emulsifier concentrations, or modifying processing conditions).
3. Record the results in the batch record, including any changes made to the formulation or process to achieve the desired rheological properties.

5.5 Stability Testing of Rheological Properties

1. Conduct stability testing on the cream to evaluate the long-term rheological stability. This includes:
   • Real-time Stability Testing: Store cream samples under normal conditions and measure the rheological properties at regular intervals to assess any changes over time.
   • Accelerated Stability Testing: Expose cream samples to higher temperatures or humidity conditions to simulate extended shelf life and observe any changes in rheological properties.
2. Ensure that the cream’s rheological properties remain stable under storage conditions, as significant changes in viscosity or flow behavior may indicate formulation instability.

5.6 Documentation and Reporting

1. Document all rheological testing activities, including:
   • The type of rheological test conducted (e.g., viscosity, yield stress, flow behavior)
   • The test equipment used and settings
   • The results obtained from each test
   • Any formulation adjustments made based on testing results
2. Prepare a Rheological Properties Analysis Report (Annexure-1) summarizing the testing methods, results, and any corrective actions taken. The report should be submitted for review and approval by the QA team.

5.7 Final Approval and Commercial Production

1. Once the cream formulation meets the required rheological specifications and has passed all stability tests, it is approved for commercial production.
2. Ensure that rheological properties are monitored during production to maintain consistency across batches.
3. Store all rheological testing data and documentation for future reference and regulatory compliance.

6. Abbreviations

• QC: Quality Control
• QA: Quality Assurance
• GMP: Good Manufacturing Practices
• API: Active Pharmaceutical Ingredient
• cP: Centipoise (Unit of Viscosity)

7. Documents

1. Rheological Properties Analysis Report (Annexure-1)
2. Formulation Development Log (Annexure-2)
3. Batch Record (Annexure-3)

8. References

• Good Manufacturing Practices (GMP) Guidelines – 21 CFR Part 211
• International Conference on Harmonisation (ICH) Q7 – Good Manufacturing Practice for Active Pharmaceutical Ingredients
• Cosmetic Science and Technology by D. A. Jones

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 Properties Analysis Report

Batch Number	Test Type	Viscosity (cP)	Flow Behavior	Elasticity	Comments
12345	Viscosity Test	4500 cP	Shear-thinning	Pass	Stable viscosity

Annexure-2: Formulation Development Log

Formulation Name	Batch Number	Ingredients	Process Parameters
Moisturizing Cream	67890	Water, Glycerin, Hyaluronic Acid	Mixing: 30 min, Temperature: 65°C

Annexure-3: Batch Record

Batch Number	Test Date	Viscosity (cP)	Elasticity Test
12345	20/08/2025	4500 cP	Pass (Elastic)

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