Capsule: SOP for Conducting Hygroscopicity Testing for Capsule Fill Materials – V 2.0

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Capsule: SOP for Conducting Hygroscopicity Testing for Capsule Fill Materials – V 2.0

Standard Operating Procedure for Conducting Hygroscopicity Testing for Capsule Fill Materials

Department Capsule Manufacturing
SOP No. SOP/CM/036/2025
Supersedes SOP/CM/036/2022
Page No. Page 1 of 6
Issue Date 01/02/2025
Effective Date 05/02/2025
Review Date 01/02/2026

1. Purpose

The purpose of this SOP is to establish the procedure for conducting hygroscopicity testing of capsule fill materials. The objective is to evaluate the moisture absorption properties of the materials to ensure stability, prevent clumping, and maintain consistency in capsule fill weights during manufacturing and storage.

2. Scope

This SOP applies to all capsule fill materials that are susceptible to moisture absorption, including active pharmaceutical ingredients (APIs), excipients, and other powdered materials used in hard gelatin capsule formulations.

3. Responsibilities

  • Formulation Development Team: Responsible for selecting the appropriate materials for hygroscopicity testing and providing guidance on the moisture sensitivity of different fill materials.
  • Quality Control (QC) Team: Responsible for conducting hygroscopicity testing, recording results, and ensuring that the materials meet the required specifications.
  • Quality Assurance (QA) Team: Ensures that the testing is conducted according to this SOP and that all records are maintained and reviewed in accordance with regulatory requirements.
  • Manufacturing Team: Responsible for ensuring that materials with high hygroscopicity are handled appropriately during the manufacturing process to prevent excessive moisture uptake.

4. Accountability

The Capsule Manufacturing Supervisor is accountable for ensuring that the hygroscopicity testing process is followed properly, while the QC Manager is responsible for reviewing the test results and ensuring the materials meet the necessary specifications for use in capsule production.

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5. Procedure

5.1 Selection of Materials for Hygroscopicity Testing

Identify the materials to be tested for hygroscopicity based on the following criteria:

  1. Moisture Sensitivity

    1. Select materials known to be sensitive to moisture absorption, including both APIs and excipients that may absorb water during handling, storage, or manufacturing.
  2. Susceptibility to Degradation

    1. Test materials that are susceptible to degradation due to moisture, such as those that may experience reduced stability, reduced efficacy, or increased impurity formation when exposed to excessive moisture.

5.2 Sample Preparation

Prepare the samples for hygroscopicity testing as follows:

  1. Weigh the Material

    1. Accurately weigh the sample material, ensuring that the amount is sufficient for both testing and any subsequent analyses. The sample size typically ranges from 10g to 100g depending on the material.
  2. Pre-Condition the Material

    1. Ensure that the material is pre-conditioned to a standardized humidity level before testing. This can involve storing the sample in a controlled environment for a specified time to ensure consistency in the testing process.

5.3 Testing Methodology

There are several methods for conducting hygroscopicity testing, depending on the equipment available:

  1. Gravimetric Method

    1. Weigh the sample before exposure to humidity, and then place the sample in a controlled environment (e.g., a humidity chamber) at a specified relative humidity (RH) and temperature.
    2. Weigh the sample at regular intervals (e.g., 1 hour, 2 hours, 4 hours, and 24 hours) to determine the moisture uptake. Continue the testing until the sample reaches a stable weight.
  2. Desiccator Method

    1. Place the sample in a desiccator over a saturated salt solution that maintains a specific relative humidity, typically between 40-90% RH. Measure the weight gain of the sample at regular intervals.
    2. This method is particularly useful for materials that may change their properties with rapid humidity changes.
  3. Dynamic Humidity Control

    1. In some cases, dynamic humidity control using a humidity-controlled chamber can be used. The material is subjected to cycling humidity levels, and the weight is measured at each cycle to assess moisture absorption and desorption properties.
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5.4 Test Conditions

Control and monitor the following parameters during hygroscopicity testing:

  1. Relative Humidity (RH)

    1. Ensure that the relative humidity is set according to the material’s typical storage conditions or the conditions specified by the formulation development team.
    2. Humidity levels typically range from 40% RH to 90% RH depending on the fill material’s known behavior.
  2. Temperature

    1. The temperature should be maintained at a constant level, typically at 25°C, unless specified otherwise by formulation development or regulatory requirements.
  3. Testing Duration

    1. Test the sample over a period of 24-48 hours, with periodic weight measurements taken at specified intervals to monitor moisture uptake and equilibrium.

5.5 Evaluation of Results

Evaluate the hygroscopicity test results based on the following:

  1. Moisture Absorption Rate

    1. Calculate the moisture absorption rate by comparing the initial and final weights of the sample. The moisture uptake should be expressed as a percentage increase in weight.
  2. Equilibrium Moisture Content

    1. Determine the equilibrium moisture content, which represents the maximum moisture level that the material can absorb under the specified conditions.
  3. Moisture Sensitivity Classification

    1. Classify the material based on its moisture absorption properties. Materials with significant moisture uptake may require additional storage or handling precautions, such as desiccants or moisture-proof packaging.

5.6 Adjustments Based on Results

If the material exhibits high moisture absorption, consider the following adjustments:

  1. Formulation Adjustment

    1. Modify the formulation by incorporating moisture-resistant excipients, such as moisture barriers or drying agents, to reduce hygroscopicity.
  2. Packaging Considerations

    1. For materials that absorb moisture rapidly, consider using moisture-proof or hermetically sealed packaging to protect the product during storage and handling.
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5.7 Documentation and Record-Keeping

Document all aspects of the hygroscopicity testing process:

  1. Testing Records

    1. Maintain detailed records of the test conditions, including relative humidity, temperature, and testing duration, as well as the results of each weight measurement.
  2. Moisture Absorption Data

    1. Record the moisture absorption rate and equilibrium moisture content for each material tested. Include a summary of the material’s moisture sensitivity classification.

6. Abbreviations

  • SOP: Standard Operating Procedure
  • QC: Quality Control
  • RH: Relative Humidity
  • API: Active Pharmaceutical Ingredient
  • GMP: Good Manufacturing Practice

7. Documents

  1. Hygroscopicity Testing Record (Annexure-1)
  2. Moisture Absorption Report (Annexure-2)

8. References

  • USP <731> – Water Content
  • FDA Guidance for Industry: Stability Testing of Drug Products
  • International Conference on Harmonization (ICH) Q1A – Stability Testing of New Drug Substances and Products

9. SOP Version

Version: 2.0

10. Approval Section

Prepared By Checked By Approved By
Signature
Date
Name
Designation
Department

11. Annexures

Annexure-1: Hygroscopicity Testing Record

Date Material Initial Weight Final Weight Moisture Absorption (%) Remarks
02/02/2025 Material A 10g 10.5g 5% Stable moisture content

Annexure-2: Moisture Absorption Report

Date Material Equilibrium Moisture Content Hygroscopicity Classification
02/02/2025 Material A 5% Moderately Hygroscopic

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 hygroscopicity testing methodology Standardization QA Head
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