Tablets: SOP for Granule and Powder Flowability Testing – V 2.0

Standard Operating Procedure for Granule and Powder Flowability Testing

Department	Quality Control
SOP No.	SOP/TAB/118/2025
Supersedes	SOP/TAB/118/2022
Page No.	Page 1 of 6
Issue Date	01/03/2026
Effective Date	06/03/2026
Review Date	01/03/2027

1. Purpose

To define the procedure for testing the flowability of granules and powder used in tablet formulations, ensuring optimal flow characteristics for processing and uniformity in tablet manufacturing.

2. Scope

This SOP applies to the testing of granules and powders used in tablet manufacturing to ensure they meet the required flowability specifications, essential for proper mixing, compression, and uniformity.

3. Responsibilities

Quality Control (QC): Responsible for performing the granule and powder flowability testing and ensuring that the results meet the specifications.
Quality Assurance (QA): Ensures that the testing is performed according to this SOP and reviews the results to confirm compliance with product specifications and regulatory standards.
Laboratory Personnel: Responsible for preparing the samples, conducting the flowability testing, and recording the results accurately.

4. Accountability

The QC Manager is accountable for ensuring that flowability testing is performed accurately and consistently. The QA Manager is responsible for reviewing and approving the test results to ensure that the product complies with internal and regulatory standards.

5. Procedure

5.1 Sample Preparation

Weigh a representative sample of the granules or powder (e.g., 50 g to 100 g) from the batch to be tested.
Ensure that the sample is free from moisture and foreign materials, as these factors can affect the flowability of the powder or granules.
Ensure that the granules or powder are at room temperature before testing to avoid any variability in flowability due to temperature changes.

5.2 Flowability Testing Methods

The following methods can be used for testing granule and powder flowability:

Angle of Repose Method:
- Place the granules or powder into a funnel and allow them to fall freely onto a flat surface.
- Measure the height and diameter of the formed powder cone.
- Calculate the angle of repose using the formula:
  - tan(θ) = h / r
  - Where:
    θ = angle of repose, h = height of the powder cone, r = radius of the powder cone base.
Flow Rate Method:
- Use a standardized powder funnel (e.g., powder flow function funnel) to measure the rate at which the powder flows through the orifice under standardized conditions.
- Record the time taken for a specific amount of powder to flow through the funnel.
Powder Flow Tester (Carr’s Index):
- Determine the bulk density and tapped density of the granules or powder.
- Calculate the Carr’s Index using the following formula:
  - Carr’s Index (%) = [(Tapped Density – Bulk Density) / Tapped Density] × 100
- Evaluate the flowability based on the Carr’s Index:
  - 0–10%: Excellent Flow
  - 11–15%: Good Flow
  - 16–20%: Fair Flow
  - 21–25%: Passable Flow
  - Above 25%: Poor Flow

5.3 Recording Results

Record all measurements, including the angle of repose, flow rate, Carr’s Index, and other relevant data in the batch record (Annexure-2).
Ensure that all results are signed, dated, and stored according to the company’s record retention policy.
If any result falls outside of the acceptance criteria, investigate and document corrective actions in the deviation report (Annexure-1).

5.4 Acceptance Criteria

For Angle of Repose: The angle should not exceed 40 degrees. Higher values indicate poor flowability.
For Flow Rate Method: The time taken for the powder to flow should meet the predefined specification. Any deviation must be documented.
For Carr’s Index: The Carr’s Index should be below 25% for satisfactory flowability. A value above 25% indicates poor flow and requires further investigation.

5.5 Documentation and Record-Keeping

Document all flowability test results, including any deviations, corrective actions, and re-tests, in the batch record (Annexure-2).
Ensure that all records are signed, dated, and stored according to the company’s record retention policy for future audits and inspections.
Maintain raw data, including time measurements, funnel measurements, and any deviation reports, for regulatory compliance and future reference.

5.6 Post-Test Actions

Clean all equipment used for granule and powder flowability testing to remove any residual material and prevent cross-contamination.
Dispose of used samples and solvents according to the company’s waste disposal procedures.
Ensure that any equipment used for flowability testing, such as the funnel, powder tester, or micrometer, is regularly calibrated and maintained according to the manufacturer’s guidelines.

6. Abbreviations

SOP: Standard Operating Procedure
GMP: Good Manufacturing Practice
QC: Quality Control
QA: Quality Assurance
API: Active Pharmaceutical Ingredient
Carr’s Index: A measure of the powder’s flowability
HPLC: High-Performance Liquid Chromatography

7. Documents

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

8. References

USP <616> – Powder Flowability Testing
21 CFR Part 211 – Current Good Manufacturing Practice for Finished Pharmaceuticals (US FDA)
European Pharmacopoeia (EP) – Specifications for Powder Flowability

9. SOP Version

Version: 2.0

10. Approval Section

	Prepared By	Checked By	Approved By
Signature
Date
Name
Designation
Department

11. Annexures

Annexure-1: Deviation Report

Deviation Date	Batch Number	Deviation Description	Corrective Action	Responsible Person
15/12/2025	Batch 001	Inconsistent particle size in coating	Adjusted homogenizer settings and re-tested	John Doe

Annexure-2: Batch Record

Batch Number	Sample Weight (g)	Homogenization Pressure (bar)	Particle Size (µm)	Coating Thickness (µm)	Result
Batch 001	100 g	1500 bar	150 µm	25 µm	Pass

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 homogenization pressure limits	Improved testing conditions	QA Head