Standard Operating Procedure for Microbial Endotoxin Testing for Tablets

Department	Quality Control
SOP No.	SOP/TAB/098/2025
Supersedes	SOP/TAB/098/2022
Page No.	Page 1 of 7
Issue Date	01/03/2026
Effective Date	06/03/2026
Review Date	01/03/2027

1. Purpose

To define the procedure for microbial endotoxin testing of tablets, ensuring that endotoxin levels in the tablets meet the regulatory limits for product safety and efficacy.

2. Scope

This SOP applies to microbial endotoxin testing of finished tablet products to ensure that the endotoxin levels do not exceed the allowable limits defined by regulatory standards.

3. Responsibilities

• Quality Control (QC): Responsible for performing the endotoxin testing, ensuring that the test is conducted according to established methods, and recording results accurately.
• Quality Assurance (QA): Ensures that the microbial endotoxin testing procedure is followed and reviews the test results for compliance with regulatory standards.
• Laboratory Personnel: Responsible for preparing the samples, performing the endotoxin test, and maintaining proper documentation throughout the testing process.

4. Accountability

The QC Manager is accountable for ensuring that microbial endotoxin testing is performed correctly according to this SOP. The QA Manager is responsible for reviewing the test results and approving the batch for release.

5. Procedure

5.1 Sample Collection

1. Collect a representative sample of tablets from the batch, as specified in the batch record or pharmacopeial guidelines (usually a minimum of 10 tablets or as specified).
2. Ensure that the tablets are free from visible defects, contamination, or external microbial contamination that may interfere with the testing process.
3. Label the sample appropriately for identification during testing.

5.2 Preparation of Test Solution

1. Crush the tablets into a fine powder using a clean mortar and pestle or tablet grinder.
2. Weigh the appropriate amount of the powdered tablet (usually 10–20 tablets) and dissolve it in a suitable solvent (e.g., pyrogen-free water, saline) to create a sample solution.
3. Ensure that the sample solution is homogeneous and filter it if necessary to remove any undissolved particles or impurities.
4. Prepare multiple sample solutions if required for testing, following the specified dilution factors.

5.3 Performing Endotoxin Test

1. For endotoxin testing, use the Limulus Amebocyte Lysate (LAL) assay or another suitable validated method, according to pharmacopeial guidelines or the batch record.
2. Prepare the LAL reagent and calibrator standards according to the manufacturer’s instructions.
3. Test the sample solution and controls by adding a specified amount of LAL reagent to each sample aliquot.
4. Incubate the samples and controls according to the method’s required conditions (e.g., temperature and time).
5. Measure the endotoxin levels using an appropriate endpoint detection method (e.g., turbidity, chromogenic, or fluorogenic assay). Record the results for each sample.

5.4 Data Recording and Calculation

1. Record the endotoxin concentration for each sample and control, including any observed discrepancies or deviations during testing (Annexure-1).
2. Calculate the endotoxin levels in the sample by comparing the results to the endotoxin standards and using the following formula:
• Endotoxin Level (EU/mL) = (Sample Reading / Standard Reading) × Standard Concentration
3. Ensure that the endotoxin levels are within the acceptable limits specified in the batch record or regulatory guidelines (usually < 0.5 EU/tablet for parenteral tablets, but may vary).

5.5 Acceptance Criteria

1. Ensure that the endotoxin level in each tablet sample does not exceed the maximum allowable limit specified in the batch record or pharmacopeial guidelines (usually ≤ 0.5 EU/tablet for parenteral tablets).
2. If the endotoxin level exceeds the acceptable limit, document the deviation in the deviation report (Annexure-2) and investigate the cause of failure.
3. Take corrective actions as necessary and perform re-testing if required.

5.6 Documentation and Record-Keeping

1. Document all endotoxin test results, including the endotoxin levels, sample preparation details, and any deviations or corrective actions, in the batch record (Annexure-1).
2. Ensure that all records are signed, dated, and stored according to the company’s record retention policy for future audits and inspections.
3. Maintain raw data, test results, and supporting documentation for future reference and regulatory compliance.

5.7 Post-Test Cleanup

1. Clean all equipment used for endotoxin testing, including the LAL reagents, sample containers, and testing instruments, according to the cleaning SOP to prevent cross-contamination between tests.
2. Ensure that all testing equipment is properly maintained and calibrated for future use.

6. Abbreviations

• SOP: Standard Operating Procedure
• GMP: Good Manufacturing Practice
• QC: Quality Control
• QA: Quality Assurance
• API: Active Pharmaceutical Ingredient
• LAL: Limulus Amebocyte Lysate
• EU: Endotoxin Units

7. Documents

1. Batch Record (Annexure-1)
2. Deviation Report (Annexure-2)

8. References

• USP <85> – Bacterial Endotoxins Test
• 21 CFR Part 211 – Current Good Manufacturing Practice for Finished Pharmaceuticals (US FDA)
• European Pharmacopoeia (EP) – Microbial Endotoxin Testing

9. SOP Version

Version: 2.0

10. Approval Section

	Prepared By	Checked By	Approved By
Signature
Date
Name
Designation
Department

11. Annexures

Annexure-1: Batch Record

Batch Number	Tablet Sample	Endotoxin Level (EU/tablet)	Result
Batch 001	Tablet Sample	0.3	Pass

Annexure-2: Deviation Report

Deviation Date	Batch Number	Deviation Description	Corrective Action	Responsible Person
12/12/2025	Batch 001	Endotoxin level exceeded limit	Rework tablet formulation and retest	Jane Doe

Revision History:

Revision Date	Revision No.	Revision Details	Reason for Revision	Approved By
01/01/2024	1.0	Initial Version	New SOP Creation	QA Head
01/02/2025	2.0	Updated Testing Methodology	Refined endotoxin testing protocols	QA Head