SOP for Randomization and Blinding/Unblinding

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Published on 22/12/2025

Standard Operating Procedure for Randomization and Blinding/Unblinding

Department	Clinical Research
SOP No.	CR/IP/036/2025
Supersedes	NA
Page No.	1 of 22
Issue Date	26/08/2025
Effective Date	01/09/2025
Review Date	01/09/2026

Table of Contents

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

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

References

Version: 1.0

Approval Section

Prepared By	Rajesh Kumar, Clinical Pharmacist
Checked By	Sunita Reddy, QA Officer
Approved By	Dr. Anil Sharma, Principal Investigator

Annexures

Annexure-1: Randomization Log

Date	Subject ID	Randomization Code	Treatment Arm	Assigned By
12/09/2025	CT2025-SITE01-051	RND-1001	A	Ravi Kumar

Annexure-2: Unblinding Record

Date	Subject ID	Reason for Unblinding	Authorized By	Outcome
15/09/2025	CT2025-SITE01-055	Serious Adverse Event	Dr. Meera Joshi	Treatment: Arm B

Annexure-3: Blinding Integrity Checklist

Date	Activity	Reviewed By	Status	Remarks
18/09/2025	Review of packaging & labeling	Sunita Sharma	Compliant	No deviations

Revision History

Revision Date	Revision No.	Revision Details	Reason for Revision	Approved By
26/08/2025	00	Initial version	New SOP creation	Head, Clinical Research

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