Standard Operating Procedure for Preservative Efficacy Testing of Creams
| Department | Creams |
|---|---|
| SOP No. | SOP/CRM/135/2025 |
| Supersedes | SOP/CRM/135/2022 |
| Page No. | Page 1 of 6 |
| Issue Date | 21/01/2026 |
| Effective Date | 26/01/2026 |
| Review Date | 21/01/2027 |
1. Purpose
The purpose of this SOP is to establish a standard procedure for conducting preservative efficacy testing (PET) of cream formulations. The effectiveness of preservatives in a cream formulation is critical for preventing microbial contamination during its shelf life. This test ensures that the preservatives used in the formulation are effective in inhibiting the growth of microorganisms.
2. Scope
This SOP applies to all cream formulations produced at the facility. It covers the procedure for testing the efficacy of preservatives in creams after they have been formulated and before they are released for distribution.
3. Responsibilities
- Production Team: Responsible for ensuring that the cream formulations are correctly prepared with the specified preservatives, and samples are provided for preservative efficacy testing.
- Quality Control (QC) Team: Responsible for performing preservative efficacy testing using appropriate microbiological methods and ensuring that the test results meet the required standards.
- Quality Assurance (QA) Team: Responsible for reviewing and approving the preservative efficacy test results to ensure compliance with regulatory requirements and internal specifications.
4. Accountability
The QC Manager is accountable for ensuring that preservative efficacy testing is carried out as per this SOP. The Production Supervisor is responsible for providing representative samples for testing. The QA Manager ensures that the test results comply with regulatory and internal quality standards.
5. Procedure
5.1 Pre-Test Preparation
- Ensure that all necessary equipment for preservative efficacy testing is available, including microbiological incubators, sterilized containers, and microbiological media (e.g., tryptic soy broth, sabouraud dextrose agar).
- Ensure that the water activity meter, autoclave, and other microbiological testing instruments are calibrated and ready for use.
- Review the batch records to identify the cream formulations to be tested and to confirm the preservatives used in the formulation.
5.2 Sample Collection
- Collect a representative sample of the cream formulation for preservative efficacy testing. The sample should be homogenous and free from contamination.
- Label each sample with the batch number, sample ID, sampling date, and preservatives used in the formulation to ensure traceability during testing.
- Ensure that the samples are collected from finished batches that have been fully processed and are ready for packaging.
5.3 Preservative Efficacy Testing Procedure
- Prepare the test according to the microbiological testing procedure:
- Microbial Challenge Test (Challenge Testing): Inoculate the cream sample with specific microorganisms, such as Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, and Candida albicans, in concentrations that represent typical contamination levels.
- Incubate the inoculated samples at a controlled temperature (e.g., 30°C for bacteria or 25°C for fungi) for a defined period, usually 7, 14, 21, and 28 days.
- At each designated time interval, take a sample from the inoculated cream and perform microbial counting using suitable microbiological media (e.g., agar plates for microbial growth).
- Perform appropriate dilution and plating techniques to quantify the microbial growth.
- For each sampling point, calculate the log reduction of microorganisms. The preservative is considered effective if it meets the required reduction criteria as per regulatory guidelines (e.g., ≥1 log reduction in microbial count).
- Record the microbial counts and other observations (e.g., changes in physical appearance) in the Preservative Efficacy Testing Log (Annexure-1).
5.4 Interpretation of Results
- Compare the microbial count at each time point with the initial inoculum. A preservative efficacy test passes if the cream formulation demonstrates a ≥1 log reduction in microbial count at the end of the test period.
- If the formulation does not meet the specified microbial reduction criteria, mark the test result as “Fail.” Investigate the cause of failure, which may include evaluating the preservative concentration, formulation, or processing methods.
- If the formulation passes the test, mark the test result as “Pass” and proceed with the next stage of production or distribution.
5.5 Post-Test Activities
- Record all test results, including batch number, sample ID, microbial count, test duration, and any corrective actions taken, in the Preservative Efficacy Testing Log (Annexure-1).
- If any sample fails the test, initiate corrective actions, which may include adjusting the preservative concentration or modifying the formulation. Re-test the sample after corrective actions.
- Submit the test results to the QA team for review and approval to ensure compliance with regulatory and internal standards.
5.6 Documentation and Record-Keeping
- Ensure that all preservative efficacy testing records are complete, accurate, and securely stored. This includes the Preservative Efficacy Testing Log (Annexure-1) and the Deviation Log (Annexure-2) for failed tests.
- Retain all records for a minimum of two years or as required by regulatory guidelines.
- 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
- PET: Preservative Efficacy Testing
7. Documents
- Annexure-1: Preservative Efficacy Testing Log
- 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
- USP <795> – Pharmaceutical Compounding of Nonsterile Preparations
9. SOP Version
Version: 2.0
10. Approval Section
| Prepared By | Checked By | Approved By | |
|---|---|---|---|
| Signature | |||
| Date | |||
| Name | |||
| Designation | |||
| Department |
11. Annexures
Annexure-1: Preservative Efficacy Testing Log
| Batch Number | Sample ID | Test Date | Microbial Count (CFU/g) | Preservative Efficacy (Log Reduction) | Operator |
|---|---|---|---|---|---|
| 12345 | S-001 | 21/01/2026 | 0 | 3.5 | John Doe |
Annexure-2: Deviation Log
| Deviation Date | Batch Number | Deviation Description | Corrective Action Taken | Operator |
|---|---|---|---|---|
| 21/01/2026 | 12345 | Preservative efficacy below acceptable limit | Adjusted preservative concentration 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 |