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Standard Operating Procedure for Randomization and Blinding/Unblinding

Purpose

The purpose of this SOP is to describe standardized procedures for randomization, blinding, and unblinding in clinical trials. These processes ensure unbiased allocation of investigational products, maintain trial integrity, and safeguard subject safety.

Scope

This SOP applies to all clinical trial staff involved in randomization, blinding, and unblinding, including investigators, pharmacists, data managers, CROs, and sponsors. It covers randomization via IVRS/IWRS systems, manual methods, maintenance of blind, and emergency unblinding procedures.

Responsibilities

• Principal Investigator (PI): Oversees randomization and ensures blinding is maintained throughout the trial.
• Pharmacist/Authorized Designee: Executes randomization assignments, dispenses blinded product, and documents code breakages.
• Data Manager: Manages randomization codes and verifies blinding integrity.
• Sponsor/CRO: Provides randomization schemes, ensures systems are validated, and oversees blinding compliance.
• Quality Assurance Officer: Reviews randomization and unblinding records during audits and inspections.

Accountability

The PI is accountable for maintaining randomization and blinding integrity. The sponsor is accountable for providing validated randomization systems and unblinding procedures.

Procedure

1. Randomization Process
Use validated IVRS/IWRS or manual sealed envelope systems for randomization.
Assign subject IDs sequentially, linked with treatment allocation.
Document allocations in Randomization Log (Annexure-1).

2. Blinding
Ensure blinding for double-blind trials by using identical packaging and labeling.
Limit access to randomization codes to authorized staff only.
File blinding documentation in ISF and TMF.

3. Emergency Unblinding
Unblinding is permitted only in medical emergencies when knowledge of treatment is essential for subject safety.
Document reason, authorization, and outcome in Unblinding Record (Annexure-2).
Notify sponsor and EC/IRB within 24 hours of unblinding.

4. Monitoring and Auditing
Sponsor monitors verify randomization compliance during site visits.
QA audits review logs for discrepancies and corrective actions.

5. Archiving
Archive randomization and blinding/unblinding records for at least 5 years post-trial or per local laws.

Abbreviations

• SOP: Standard Operating Procedure
• PI: Principal Investigator
• IP: Investigational Product
• CRO: Clinical Research Organization
• IVRS: Interactive Voice Response System
• IWRS: Interactive Web Response System
• ISF: Investigator Site File
• TMF: Trial Master File
• QA: Quality Assurance

Documents

1. Randomization Log (Annexure-1)
2. Unblinding Record (Annexure-2)
3. Blinding Integrity Checklist (Annexure-3)

References

• ICH E9 – Statistical Principles for Clinical Trials
• US FDA – Randomization and Blinding Guidance
• EMA Clinical Trial Regulation
• CDSCO Clinical Trial Rules, 2019
• WHO – Good Clinical Trial Practices

Version: 1.0

Approval Section

Annexures

Annexure-1: Randomization Log

Annexure-2: Unblinding Record

Annexure-3: Blinding Integrity Checklist

Revision History

For more SOPs visit: Pharma SOP