and regulatory requirements.

2. Scope

This SOP applies to all injectable dosage forms developed or manufactured in the facility, including intravenous, intramuscular, subcutaneous, intraosseous, and prefilled syringe formats.

3. Responsibilities

• Formulation Development Team: Conducts viscosity studies, documents evaluations, and recommends optimization strategies.
• Analytical Development Scientist: Performs viscosity testing using validated methods.
• Quality Assurance (QA): Reviews documentation and ensures compliance with GMP.
• Project Lead: Coordinates between formulation and analytical teams for timely completion.

4. Accountability

The Head of Formulation Development is accountable for ensuring viscosity parameters meet defined product quality requirements and are aligned with the intended administration route.

5. Procedure

5.1 Define Target Viscosity Range

1. Determine acceptable viscosity range based on:
   • Route of administration
   • Needle gauge compatibility
   • Syringe plunger force
   • Regulatory expectations
2. Refer to clinical data and existing products for benchmarking.

5.2 Selection of Rheological Testing Method

1. Choose appropriate rheometer or viscometer (e.g., Brookfield, rotational cone and plate).
2. Validate viscosity testing method per ICH Q2(R1) requirements.
3. Perform measurements at controlled temperature (25°C ± 1°C or 37°C ± 1°C).

5.3 Experimental Viscosity Evaluation

1. Prepare trial formulations using different concentrations of:
   • Polymers (e.g., HPMC, PVP)
   • Solubilizers (e.g., PEG 400, Glycerin)
   • Buffers or tonicity modifiers
2. Measure viscosity at multiple shear rates to evaluate pseudoplasticity or Newtonian behavior.
3. Record values in Viscosity Optimization Log (Annexure-1).

5.4 Syringeability and Injectability Testing

1. Conduct plunger force testing using universal testing machine or syringe force analyzer.
2. Test syringeability using intended device and 23G or 25G needle depending on route.
3. Evaluate subjective patient comfort through simulation studies (if applicable).

5.5 Optimization and Finalization

1. Analyze data trends and identify optimal viscosity formulation.
2. Confirm formulation robustness across batches.
3. Document optimization summary (Annexure-2).
4. Update formulation development report accordingly.

5.6 Documentation and Review

1. Ensure all raw data, graphs, test conditions, and calculations are reviewed by QA.
2. Maintain signed printouts in development dossier.

6. Abbreviations

• SOP: Standard Operating Procedure
• QA: Quality Assurance
• HPMC: Hydroxypropyl Methylcellulose
• PVP: Polyvinylpyrrolidone
• PEG: Polyethylene Glycol

7. Documents

1. Viscosity Optimization Log – Annexure-1
2. Optimization Summary Report – Annexure-2
3. Final Formulation Justification Sheet – Annexure-3

8. References

• ICH Q8(R2): Pharmaceutical Development
• ICH Q2(R1): Validation of Analytical Procedures
• USP <797> and <1207> – Sterile Compounding and Packaging Integrity

9. SOP Version

Version: 2.0

10. Approval Section

	Prepared By	Checked By	Approved By
Signature
Date
Name
Designation	Formulation Scientist	QA Reviewer	Head – QA
Department	R&D	Quality Assurance	Quality Assurance

11. Annexures

Annexure-1: Viscosity Optimization Log

Batch ID	Polymer Used	Concentration (%)	Viscosity (cP)	Shear Rate	Analyst	Date
DEV-010	HPMC	0.5	18.4	50 s⁻¹	Rajesh Kumar	10/06/2025

Annexure-2: Optimization Summary Report

Parameter	Summary
Target Range	15–25 cP at 25°C
Final Composition	HPMC 0.5%, NaCl 0.9%, Water for Injection
Conclusion	Acceptable for subcutaneous use with 25G needle

Annexure-3: Final Formulation Justification Sheet

Component	Function	Concentration (%)	Justification
HPMC	Viscosity enhancer	0.5	Ensures optimal viscosity for subcutaneous delivery
NaCl	Tonicity adjuster	0.9	Maintains isotonicity with blood plasma

Revision History

Revision Date	Revision No.	Details	Reason	Approved By
01/02/2022	1.0	Initial version released	New SOP	QA Head
18/06/2025	2.0	Expanded scope and annexures added	Annual review	QA Head