Standard Operating Procedure for Optimizing Viscosity in Cream Formulations

Department	Creams
SOP No.	SOP/CRM/032/2025
Supersedes	SOP/CRM/032/2022
Page No.	Page 1 of 6
Issue Date	04/08/2025
Effective Date	09/08/2025
Review Date	04/08/2026

1. Purpose

The purpose of this Standard Operating Procedure (SOP) is to establish the process for optimizing viscosity in cream formulations. The viscosity of a cream formulation is critical to its sensory characteristics, stability, and performance. This SOP ensures that viscosity is controlled and optimized to meet product specifications.

2. Scope

This SOP applies to all cream formulations that require viscosity optimization. It covers the methods for controlling and adjusting viscosity through formulation adjustments and process parameters.

3. Responsibilities

• Formulation Development Team: Responsible for formulating and optimizing the viscosity of cream products. They must determine the appropriate ingredients and quantities to achieve the desired viscosity.
• Quality Control (QC): Responsible for measuring and testing the viscosity of the cream formulations to ensure they meet the required specifications.
• Quality Assurance (QA): Ensures that the viscosity optimization process is compliant with internal and regulatory standards, and oversees the review and approval of viscosity testing results.
• Production Team: Implements the viscosity optimization procedure during production, adjusting process parameters as necessary to achieve the desired viscosity.

4. Accountability

The Head of Creams Manufacturing is responsible for overseeing the viscosity optimization process. The QA Manager is accountable for ensuring that all viscosity optimization activities are documented and comply with GMP standards.

5. Procedure

5.1 Determining Desired Viscosity

1. The first step in optimizing viscosity is to determine the desired viscosity for the cream formulation. The desired viscosity depends on the type of cream, its intended use, and consumer preferences. Common types of creams and their typical viscosity ranges include:
   • Light creams: Lower viscosity (e.g., 2000-4000 cP)
   • Thick creams: Higher viscosity (e.g., 5000-8000 cP)
2. Consult the formulation specifications to establish the target viscosity and the expected range based on the intended use and packaging.
3. Ensure that the viscosity is consistent with regulatory guidelines and marketing requirements for the product category.

5.2 Selection of Ingredients for Viscosity Control

1. Select appropriate ingredients to modify and control the viscosity of the cream formulation. Common ingredients that influence viscosity include:
   • Thickeners and Gelling Agents: Carbomers, xanthan gum, and cellulose derivatives
   • Emulsifiers: Stearic acid, cetyl alcohol, and other emulsifying waxes
   • Solvents: Water and alcohol
   • Polymeric materials: Used to control both viscosity and texture
2. Choose the appropriate thickening agents based on the desired cream texture and the type of emulsion (e.g., oil-in-water or water-in-oil).

5.3 Adjusting Process Parameters for Viscosity Optimization

1. Adjust the following process parameters to optimize viscosity during the manufacturing process:
   • Mixing Speed: Higher mixing speeds can increase the viscosity by promoting better dispersion of thickeners.
   • Mixing Time: Adequate mixing time ensures proper activation of thickeners and emulsifiers.
   • Temperature: Temperature control can influence the viscosity by altering the solubility and behavior of thickeners and emulsifiers.
2. Monitor viscosity at different stages of the manufacturing process to ensure it is within the desired range.
3. Make adjustments to the mixing speed or temperature if the viscosity is too low or too high during production. Record all changes made to the process.

5.4 Testing and Measurement of Viscosity

1. Measure the viscosity of the cream at various stages of production using a suitable viscometer (e.g., Brookfield viscometer or rotational viscometer). Perform the following:
   • Measure viscosity immediately after mixing, before cooling, and after cooling to ambient temperature.
   • Ensure that viscosity measurements are taken at consistent temperatures to avoid any variability in results.
   • Document the viscosity at each stage to identify any trends or issues that may need attention.
2. If viscosity falls outside the acceptable range, make the necessary adjustments to the formulation or process and retest.

5.5 Stability Testing for Viscosity

1. Conduct stability testing to ensure that the cream maintains its desired viscosity over time under various environmental conditions. Testing should include:
   • Real-time stability testing: Store samples at normal storage conditions and measure viscosity at regular intervals.
   • Accelerated stability testing: Expose samples to high temperature and humidity conditions to simulate prolonged storage and observe any viscosity changes.
2. Document all findings from stability tests, including any changes in viscosity and the potential impact on product performance.
3. If viscosity changes significantly over time, consider modifying the formulation or adjusting the process to prevent instability.

5.6 Documentation of Viscosity Optimization

1. Document all activities related to viscosity optimization, including:
   • Ingredients used for viscosity control
   • Process parameters (e.g., temperature, mixing speed, and time)
   • Viscosity measurements and test results at different stages of production
   • Stability test results, including viscosity changes over time
2. Prepare a Viscosity Optimization Report (Annexure-1) summarizing all results and adjustments made during the process.
3. Submit the Viscosity Optimization Report for review and approval by the QA team before moving to the final stages of production.

5.7 Final Approval for Commercial Production

1. After viscosity optimization is complete and the cream formulation has passed all stability and testing requirements, finalize the formulation for commercial production.
2. Ensure that the viscosity of the final product is consistent with the product specifications and consumer expectations.
3. Store the final viscosity data and documentation for future reference and regulatory compliance.

6. Abbreviations

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

7. Documents

1. Viscosity Test Results (Annexure-1)
2. Formulation Records (Annexure-2)
3. Stability Testing Report (Annexure-3)

8. References

• Good Manufacturing Practices (GMP) Guidelines – 21 CFR Part 211
• Pharmaceutical Technology: Principles and Practices by William B. Roush
• ISO 9001:2015 – Quality Management Systems

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 Test Results

Test Date	Batch Number	Viscosity (cP)	Test Results
05/08/2025	12345	4500 cP	Pass

Annexure-2: Formulation Records

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

Annexure-3: Stability Testing Report

Test Type	Test Date	Viscosity Observations	Approval Status
Accelerated Stability	10/08/2025	Viscosity remained stable	Approved

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