SOP Guide for Pharma

Sterile Injectable Manufacturing: SOP for Assay Testing of Active Ingredients in Injections – V 2.0

Sterile Injectable Manufacturing: SOP for Assay Testing of Active Ingredients in Injections – V 2.0

Standard Operating Procedure for Assay Testing of Active Ingredients in Injections


Department Sterile Injectable Manufacturing
SOP No. SOP/SIM/065/2025
Supersedes SOP/SIM/065/2022
Page No. Page 1 of 15
Issue Date 18/06/2025
Effective Date 20/06/2025
Review Date 18/06/2026

1. Purpose

This SOP defines the method for performing assay testing of active pharmaceutical ingredients (APIs) present in injectable drug products to confirm their potency and compliance with regulatory and pharmacopeial specifications.

2. Scope

This procedure applies

to Quality Control personnel performing assay testing of all sterile injectable formulations produced in the facility using validated analytical methods such as HPLC, UV, or titration.

3. Responsibilities

  • QC Analyst: Responsible for executing assay testing and recording data accurately.
  • QC Reviewer: Responsible for verifying calculations, chromatograms, and final reports.
  • QA Officer: Responsible for batch release approval based on results.

4. Accountability

The Head of Quality Control is accountable for ensuring that assay testing is carried out in accordance with this SOP and applicable regulatory standards.

5. Procedure

5.1 General Guidelines

  1. Perform assay testing as per the approved specification and validated test method.
  2. Ensure all reagents and instruments are within calibration and validity dates.
  3. Follow ALCOA+ principles for data integrity and GMP compliance.

5.2 Sample Preparation

  1. Receive samples from production or stability in double-sealed condition.
  2. Prepare sample solution as per the defined method—dilution, filtration, or extraction.
  3. Use Class A volumetric glassware and calibrated balances.

5.3 HPLC Method (if applicable)

  1. Set the chromatographic conditions as per the method (e.g., mobile phase, flow rate, wavelength).
  2. Inject system suitability standard and confirm parameters (theoretical plates, tailing factor, RSD).
  3. Inject sample and standard preparations in duplicate or triplicate.
  4. Calculate the assay by comparing the peak area of sample vs. standard.

5.4 UV Spectrophotometry Method (if applicable)

  1. Zero the instrument using blank solution.
  2. Measure absorbance of standard and sample solutions at specified wavelength.
  3. Calculate concentration based on standard curve or absorbance ratio.

5.5 Titration Method (if applicable)

  1. Prepare the sample and titrant as per the method SOP.
  2. Titrate using indicator or potentiometric endpoint.
  3. Calculate API content based on titrant volume and equivalence factor.

5.6 Documentation and Calculations

  1. Record raw data, instrument printouts, chromatograms, and calculations.
  2. Fill the Assay Testing Report (Annexure-1).
  3. Attach Certificate of Analysis (Annexure-2) for batch review.

5.7 Acceptance Criteria

API content must be within ±5% of the labeled claim unless otherwise specified in pharmacopoeial monograph or regulatory filing.

6. Abbreviations

  • API: Active Pharmaceutical Ingredient
  • HPLC: High Performance Liquid Chromatography
  • UV: Ultraviolet Spectrophotometry
  • ALCOA: Attributable, Legible, Contemporaneous, Original, Accurate
  • SOP: Standard Operating Procedure

7. Documents

  1. Assay Testing Report – Annexure-1
  2. Certificate of Analysis (CoA) – Annexure-2
  3. Instrument Calibration Log – Annexure-3

8. References

  • USP General Chapter <621>, <731>, <851>
  • ICH Q2(R2): Validation of Analytical Procedures
  • 21 CFR Part 211 – Current Good Manufacturing Practice

9. SOP Version

Version: 2.0

10. Approval Section

Prepared By Checked By Approved By
Signature
Date
Name
Designation QC Analyst QC Reviewer Head QA
Department Quality Control Quality Control Quality Assurance

11. Annexures

Annexure-1: Assay Testing Report

Batch No. Product Test Method Result (%) Tested By
AMP-2025 Ampicillin Injection HPLC 99.4 Neha Reddy

Annexure-2: Certificate of Analysis (CoA)

Product Batch No. API Assay Complies Released By
Meropenem Injection MER-025 101.2% Yes Sunita Patil

Annexure-3: Instrument Calibration Log

Date Instrument ID Type Calibrated By Status
17/06/2025 HPLC-03 HPLC Rajesh Kumar Pass

Revision History

Revision Date Revision No. Details Reason Approved By
05/01/2022 1.0 Initial version New SOP QA Head
18/06/2025 2.0 Revised limits and included UV method Periodic Review QA Head
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