of solid oral dosage forms such as tablets, hard gelatin capsules, and soft gelatin capsules. This ensures dosage consistency, regulatory compliance, and batch acceptance based on pharmacopeial specifications.

2. Scope

This SOP applies to the Analytical Method Development department responsible for method development and validation for uniformity of mass as per USP <905>, IP, BP, and Ph. Eur. It covers all development-stage and commercial solid dosage products.

3. Responsibilities

• Analytical Scientist: Performs method development, executes mass measurements, and validates the method.
• Formulation Development: Provides batch size, unit weight, and dosage information.
• QA Officer: Reviews and approves method validation protocol and results.
• Weighing Technician: Maintains weighing balance and logs calibration data.

4. Accountability

The Head of Analytical Method Development is accountable for ensuring that the uniformity of mass method is accurate, reproducible, and compliant with regulatory requirements.

5. Procedure

5.1 Equipment and Materials

1. Analytical balance (0.1 mg readability) calibrated and qualified
2. Validated data recording log or software
3. Sample solid dosage units (n = 20 or 10 depending on regulatory requirements)
4. Anti-static devices if required

5.2 Method Development Strategy

1. Determine expected average weight based on formulation target fill weight.
2. Ensure representative sampling from a validated batch.
3. For tablets, assess whole units without splitting or altering coating.
4. For capsules, weigh intact capsules and, if required, weigh empty shells separately to compute net fill weight.

5.3 Test Procedure

1. Calibrate the analytical balance using certified calibration weights before weighing samples.
2. Weigh individually 20 units and record their individual weights in mg.
3. Calculate the mean weight of the 20 units.
4. Determine the percentage deviation of each unit from the mean using the formula:
   Deviation (%) = [(Individual weight - Mean weight)/Mean weight] × 100
5. For capsules, if content uniformity must be assessed, open 10 capsules, remove and weigh contents, then calculate content mass.

5.4 Acceptance Criteria

1. For tablets/capsules with mean mass ≤ 80 mg:
   • Not more than 2 of 20 units should deviate from ±10% of the average mass
   • None should deviate by more than ±20%
2. For mean mass > 80 mg and < 250 mg:
   • Not more than 2 units may deviate by ±7.5%
   • None beyond ±15%
3. For mean mass ≥ 250 mg:
   • Not more than 2 may deviate by ±5%
   • None by more than ±10%

5.5 Method Validation

1. Precision: Repeat weighing by another analyst or day to determine RSD% of mean weight.
2. Robustness: Validate under varied environmental conditions (humidity, anti-static control).
3. Balance Range Check: Confirm weight range is within instrument linear range.
4. System Suitability: Confirm calibration certificate is valid and balance sensitivity matches test sample weight.

6. Abbreviations

• SOP: Standard Operating Procedure
• RSD: Relative Standard Deviation
• mg: Milligram
• USP: United States Pharmacopeia

7. Documents

1. Uniformity of Mass Method Development Log – Annexure-1
2. Weight Deviation Calculation Sheet – Annexure-2
3. Balance Calibration Certificate – Annexure-3

8. References

• USP <905>: Uniformity of Dosage Units
• Ph. Eur. 2.9.5 Uniformity of Mass
• Indian Pharmacopeia (IP)
• 21 CFR Part 211.160 – cGMP for Laboratory Controls

9. SOP Version

Version: 2.0

10. Approval Section

	Prepared By	Checked By	Approved By
Signature
Date
Name	Vikram Soni	Reena Joshi	Dr. Harshita Goyal
Designation	Analytical Scientist	QA Reviewer	Head – AMD
Department	Analytical Method Development	Quality Assurance	Analytical Method Development

11. Annexures

Annexure-1: Uniformity of Mass Method Development Log

Details sample code, dosage form, batch number, analyst, number of units weighed, and comments on weighability or sample variability.

Annexure-2: Weight Deviation Calculation Sheet

Unit No.	Individual Weight (mg)	Mean Weight (mg)	Deviation (%)	Status
1	505.1	500.2	+0.98	Pass
2	495.0	500.2	-1.04	Pass

Annexure-3: Balance Calibration Certificate

Issued by: LabMet Instruments Pvt. Ltd.
Date of Calibration: 15/05/2025
Next Due: 15/11/2025
Serial No.: BLC-2986
Status: Within Tolerance

Revision History:

Revision Date	Revision No.	Details	Reason	Approved By
01/06/2025	2.0	Updated acceptance criteria and annexure structure	Annual Review	Dr. Harshita Goyal
10/04/2022	1.0	Initial Release	New SOP	QA Head