Standard Operating Procedure for pH Adjustment in Cream Formulations

Department	Creams
SOP No.	SOP/CRM/034/2025
Supersedes	SOP/CRM/034/2022
Page No.	Page 1 of 5
Issue Date	14/08/2025
Effective Date	19/08/2025
Review Date	14/08/2026

1. Purpose

The purpose of this Standard Operating Procedure (SOP) is to outline the procedure for adjusting the pH of cream formulations. The pH of a cream formulation plays a significant role in product stability, safety, and efficacy. This SOP ensures that the pH is optimized to meet the required specifications for both consumer use and regulatory compliance.

2. Scope

This SOP applies to all cream formulations developed within the Creams Department that require pH adjustment. It covers the methods used to adjust pH, including monitoring, testing, and ensuring the formulation meets the desired pH range.

3. Responsibilities

• Formulation Development Team: Responsible for selecting the appropriate ingredients and ensuring that the cream formulation is designed to achieve the desired pH range.
• Quality Control (QC): Responsible for monitoring and testing the pH of cream formulations at various stages of production to ensure the pH meets the specified criteria.
• Quality Assurance (QA): Ensures that pH adjustment is conducted according to this SOP and in compliance with GMP standards and regulatory guidelines.
• Production Team: Implements the pH adjustment procedure during manufacturing and ensures that the pH is properly controlled throughout the process.

4. Accountability

The Head of Creams Manufacturing is responsible for overseeing the pH adjustment process. The QA Manager is accountable for ensuring that the pH adjustment is properly documented and complies with internal quality standards and regulatory requirements.

5. Procedure

5.1 Determining the Desired pH Range

1. The desired pH range for the cream formulation is determined based on the intended use of the product. Typical pH ranges for cream formulations are:
   • Facial creams: pH range of 4.5–6.0
   • Body creams: pH range of 5.0–7.0
   • Anti-acne creams: pH range of 4.0–5.5
2. The selected pH range must ensure product safety, stability, and efficacy, as well as compliance with regulatory standards for topical cosmetic products.
3. Consult the formulation specifications to establish the target pH and the acceptable range based on the cream’s intended use and target market.

5.2 pH Monitoring and Testing

1. Measure the pH of the cream formulation at various stages of production, including:
   • After mixing all ingredients
   • After heating and cooling the formulation
   • Before packaging
2. Use a calibrated pH meter or pH indicator strips to measure the pH of the formulation. Ensure that the equipment is calibrated according to the manufacturer’s instructions to ensure accuracy.
3. Record the pH values at each stage in the batch record and compare them to the target pH range. If the pH is outside the acceptable range, proceed with pH adjustment.

5.3 pH Adjustment

1. If the pH is not within the desired range, use appropriate pH adjusters to bring the formulation into specification. Common pH adjusters include:
   • Acidic pH adjusters: Citric acid, lactic acid, phosphoric acid
   • Basic pH adjusters: Sodium hydroxide, triethanolamine
2. Add the pH adjuster in small increments, stirring the formulation continuously until the desired pH is achieved.
3. After each addition of the pH adjuster, allow the formulation to equilibrate and re-measure the pH to ensure it is within the acceptable range.
4. Record the type and quantity of pH adjuster used in the batch record.

5.4 pH Re-check and Stability Testing

1. After the pH has been adjusted, recheck the pH of the formulation to confirm it is within the desired range. Ensure that the pH remains stable over time.
2. If necessary, conduct stability tests to assess the pH stability of the formulation over time under various storage conditions (e.g., real-time stability and accelerated stability tests).
3. Monitor the pH at regular intervals during the stability tests to identify any significant changes in pH that could affect the product’s quality or stability.
4. Document all pH testing results, including initial and final pH readings, as well as any adjustments made.

5.5 Documentation of pH Adjustment

1. Document the entire pH adjustment process, including:
   • The initial pH measurement and any deviations from the target pH range
   • The type and quantity of pH adjuster used
   • Final pH measurement after adjustment
   • Any stability test results related to pH
2. Prepare a pH Adjustment Report (Annexure-1) that includes all data and decisions made during the pH adjustment process.
3. Submit the pH Adjustment Report for review and approval by the QA team before moving to the final stages of product development.

5.6 Final Approval and Commercial Production

1. Once the pH adjustment is complete and the formulation meets the desired specifications, the cream is ready for the final stages of product development, including batch scaling and commercial production.
2. Ensure that the pH is stable and within the required range throughout the product’s shelf life.
3. Document all relevant data, including the final pH value, in the product’s master record for future reference.

6. Abbreviations

• QC: Quality Control
• QA: Quality Assurance
• GMP: Good Manufacturing Practices
• pH: Potential of Hydrogen
• API: Active Pharmaceutical Ingredient

7. Documents

1. pH Adjustment Report (Annexure-1)
2. Formulation Development Log (Annexure-2)
3. Stability Testing Report (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
• FDA Guidelines for Cosmetic Product Safety

9. SOP Version

Version: 2.0

10. Approval Section

	Prepared By	Checked By	Approved By
Signature
Date
Name
Designation
Department

11. Annexures

Annexure-1: pH Adjustment Report

Batch Number	Initial pH	pH Adjuster Used	Final pH	Adjustment Date
12345	5.2	Citric Acid	5.5	15/08/2025

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: Stability Testing Report

Test Type	Test Date	pH Observations	Approval Status
Accelerated Stability	20/08/2025	No change in pH	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