newly developed or revised method to demonstrate equivalency and justify method replacement or parallel usage.

2. Scope

This SOP applies to Analytical Method Development and Quality Control teams when transferring from an existing method to a new method or when introducing alternate methods for regulatory, technical, or operational improvements.

3. Responsibilities

• Method Development Scientist: Designs and coordinates the bridging study.
• QC Analyst: Performs analyses using both methods on the same sample sets.
• QA Executive: Reviews the comparative data and verifies report integrity and compliance.

4. Accountability

The Head of Analytical Method Development is accountable for ensuring that method bridging studies are performed in accordance with applicable guidelines and documented appropriately.

5. Procedure

5.1 Study Design

1. Select representative batches (e.g., 3–6) of the product for testing.
2. Analyze each batch in triplicate using:
   • Existing Method: Fully validated and currently approved method.
   • New Method: Recently validated or optimized method.
3. Ensure both methods are executed under similar environmental and instrumental conditions.

5.2 Parameters to Compare

• Assay (% content)
• Related substances (individual impurities)
• System suitability parameters (e.g., %RSD, resolution)

5.3 Acceptance Criteria

• Assay: Mean difference between methods NMT ±2.0%
• Impurities: Individual impurity deviation NMT ±20%
• Precision: RSD for both methods NMT 2.0%
• System Suitability: Must meet specification for both methods independently

5.4 Statistical Comparison

1. Use paired t-test for mean comparison.
2. Calculate correlation coefficient (r) between methods; r ≥ 0.98 required.
3. Plot comparative graphs (scatter, trend, or Bland-Altman) to support visual equivalency.

5.5 Documentation

1. Record raw data, chromatograms, and calculation sheets.
2. Prepare a bridging report including:
   • Executive summary
   • Sample details
   • Data comparison tables
   • Statistical outcomes
   • Conclusion and justification

5.6 Change Control and Regulatory Filing

1. If the new method is intended for regulatory submission or internal change, initiate a Change Control (CC) process.
2. Attach bridging study report and approval as supporting documentation.

6. Abbreviations

• API: Active Pharmaceutical Ingredient
• RSD: Relative Standard Deviation
• CC: Change Control
• ICH: International Council for Harmonisation

7. Documents

1. Bridging Study Data Sheet – Annexure-1
2. Comparative Method Summary Table – Annexure-2
3. Statistical Analysis Report – Annexure-3

8. References

• ICH Q2(R1): Validation of Analytical Procedures
• ICH Q14: Analytical Procedure Development
• FDA Analytical Procedures and Methods Validation Guidance

9. SOP Version

Version: 2.0

10. Approval Section

	Prepared By	Checked By	Approved By
Signature
Date
Name	Anita Kapoor	Devashish Kulkarni	Sunita Reddy
Designation	Method Development Scientist	QA Reviewer	Head – AMD
Department	Analytical Method Development	QA	Analytical Method Development

11. Annexures

Annexure-1: Bridging Study Data Sheet

Sample ID	Assay (%) – Existing	Assay (%) – New	Difference (%)	Status
BS-298-01	98.7	99.2	+0.5	Pass

Annexure-2: Comparative Method Summary Table

Parameter	Existing Method	New Method
Column	C18, 250 mm × 4.6 mm	C18, 150 mm × 4.6 mm
Mobile Phase	Buffer:ACN (65:35)	Buffer:ACN (60:40)
Run Time	20 min	12 min
Detection	UV 254 nm	UV 254 nm

Annexure-3: Statistical Analysis Report

Paired t-test yielded p-value = 0.237 (>0.05), indicating no significant difference. Correlation coefficient r = 0.993. Bridging successful and method equivalency established.

Revision History:

Revision Date	Revision No.	Details	Reason	Approved By
21/05/2025	2.0	Expanded statistical tools and added regulatory linkage to ICH Q14	Annual SOP Review	Sunita Reddy
05/09/2022	1.0	Initial SOP Release	New SOP	QA Head