Sterile Injectable Manufacturing: SOP for Designing Stability-Indicating Formulations – V 2.0

Standard Operating Procedure for Designing Stability-Indicating Formulations

Department	Product Development
SOP No.	SOP/SIM/111/2025
Supersedes	SOP/SIM/111/2022
Page No.	Page 1 of 12
Issue Date	18/06/2025
Effective Date	20/06/2025
Review Date	18/06/2026

1. Purpose

To establish a procedure for designing stability-indicating formulations for sterile injectable products that ensure product quality, safety, and efficacy over its intended shelf life.

2. Scope

This SOP applies to the formulation development team involved in the design and evaluation of sterile injectable products under stability study protocols, covering early-phase development through final formulation

lock.

3. Responsibilities

Formulation Scientist: Responsible for designing and evaluating formulation stability.
Analytical Scientist: Develop and validate stability-indicating methods.
QA Department: Ensure documentation and review of stability results.

4. Accountability

Head – Product Development and Head – QA shall be accountable for compliance with this SOP.

5. Procedure

5.1 Preformulation Studies

Review physicochemical properties of the drug substance (solubility, pKa, logP, hygroscopicity).
Conduct compatibility screening with potential excipients under stress conditions.
Evaluate pH stability and solubility range to select optimal buffer system.

5.2 Design of Formulation

Select stabilizers, antioxidants, pH modifiers, tonicity agents, and surfactants based on drug profile.
Formulate 3–5 pilot batches with varied excipient concentrations.
Filter-sterilize or aseptically prepare formulations and fill in appropriate primary packaging (vial, PFS).

5.3 Stability Study Protocol

Follow ICH Q1A(R2) guidelines for stability testing.
Recommended conditions:
- 25°C ± 2°C / 60% RH ± 5% RH (long-term)
- 30°C ± 2°C / 65% RH ± 5% RH (intermediate)
- 40°C ± 2°C / 75% RH ± 5% RH (accelerated)

5.4 Analytical Evaluation

Stability indicating parameters:
- Appearance, pH, assay, degradation products
- Particulate matter, sub-visible particles
- Sterility and endotoxin (where required)
Use validated stability-indicating HPLC or UV methods.

5.5 Data Review and Interpretation

Summarize trends and OOT/OOS occurrences.
Formulation selected must meet all critical quality attributes through the defined shelf life.
Prepare summary report with statistical evaluation of data.

6. Abbreviations

ICH: International Council for Harmonisation
RH: Relative Humidity
OOT: Out of Trend
OOS: Out of Specification
PFS: Prefilled Syringe

7. Documents

Formulation Development Worksheet – Annexure-1
Stability Study Protocol Template – Annexure-2
Stability Data Summary Table – Annexure-3

8. References

ICH Q1A(R2) Stability Testing of New Drug Substances and Products
FDA Guidance for Industry: Stability Testing of Drug Substances

9. SOP Version

Version: 2.0

10. Approval Section

	Prepared By	Checked By	Approved By
Signature
Date
Name
Designation	Formulation Scientist	QA Executive	Head QA
Department	Product Development	Quality Assurance	Quality Assurance

11. Annexures

Annexure-1: Formulation Development Worksheet

Document covering formulation trials, excipients used, and rationale for selection.

Annexure-2: Stability Study Protocol Template

Template including storage conditions, time points, test parameters, and sample pull schedule.

Annexure-3: Stability Data Summary Table

Time Point	Storage Condition	Assay (%)	Degradation (%)	Appearance	pH
0M	25°C/60% RH	100.0	0.0	Clear	6.8
6M	25°C/60% RH	98.2	0.5	Clear	6.7

Revision History

Revision Date	Revision No.	Details	Reason	Approved By
12/01/2022	1.0	Initial version	New SOP	QA Head
18/06/2025	2.0	Expanded to include Annexures and ICH harmonization	Periodic Review	QA Head