compliance with regulatory expectations.

2. Scope

This SOP applies to the Analytical Method Development (AMD) department involved in developing methods for characterization and quality control of liposomal drug formulations intended for preclinical, clinical, or commercial use.

3. Responsibilities

• Analytical Scientist: Designs and develops analytical methods specific to liposomes and performs method validation activities.
• Formulation Scientist: Provides composition details and formulation attributes necessary for method development.
• QA Officer: Verifies data integrity, reviews validation protocols, and ensures adherence to GMP and ICH guidelines.
• Head – AMD: Approves method development strategies and validation summaries for regulatory use.

4. Accountability

The Head of Analytical Method Development is accountable for the suitability, robustness, and regulatory compliance of all methods developed for liposomal drug product testing.

5. Procedure

5.1 Method Development Strategy

1. Collect detailed product knowledge including lipid composition, drug loading, and dosage form (e.g., injectable, topical).
2. Define critical quality attributes (CQAs) such as:
   • Particle size distribution
   • Encapsulation efficiency
   • Surface charge (zeta potential)
   • Drug release profile
   • Lipid degradation products
3. Select appropriate analytical platforms:
   • DLS for particle size
   • HPLC or UV for assay and release studies
   • Transmission Electron Microscopy (TEM) for morphology
   • ICP-MS or GC for residual solvents and metal analysis

5.2 Encapsulation Efficiency Determination

1. Use ultracentrifugation or dialysis method to separate free drug from liposomal-entrapped drug.
2. Quantify free drug using validated HPLC method.
3. Calculate efficiency:
   • % Encapsulation = [(Total Drug – Free Drug)/Total Drug] × 100
4. Document values in Annexure-1: Encapsulation Efficiency Log.

5.3 Particle Size and Zeta Potential

1. Use DLS instrument calibrated with polystyrene standards.
2. Prepare dilution as per instrument SOP.
3. Measure:
   • Average size (nm), PDI (polydispersity index)
   • Zeta potential (mV)
4. Acceptance: Size < 200 nm, PDI < 0.3, Zeta potential ±30 mV (product-specific).

5.4 Drug Release and In-Vitro Performance

1. Use dialysis bag or Franz diffusion cell system with suitable medium.
2. Withdraw samples at defined intervals and analyze using validated HPLC/UV method.
3. Plot cumulative % drug release vs time and determine release kinetics (zero-order, first-order, Higuchi, Korsmeyer-Peppas models).
4. Record in Annexure-2: Release Profile Log.

5.5 Method Validation Parameters

1. Validate methods for:
   • Specificity
   • Linearity and range
   • Accuracy and precision
   • LOD and LOQ
   • Robustness
2. Use ICH Q2(R2) guidelines for reporting validation data.
3. Document validation results in Annexure-3: Method Validation Summary.

5.6 Stability-Indicating Capability

1. Subject liposomal formulation to forced degradation conditions (heat, light, oxidation).
2. Analyze for breakdown of lipids and drug leakage using HPLC, GC, or DLS.
3. Ensure method can distinguish degradation products from intact liposome.

6. Abbreviations

• HPLC: High Performance Liquid Chromatography
• DLS: Dynamic Light Scattering
• CQA: Critical Quality Attribute
• LOD: Limit of Detection
• LOQ: Limit of Quantification
• SOP: Standard Operating Procedure

7. Documents

1. Encapsulation Efficiency Log – Annexure-1
2. Release Profile Log – Annexure-2
3. Method Validation Summary – Annexure-3

8. References

• ICH Q2(R2) – Validation of Analytical Procedures
• USP <1049> – Liposomes: Characterization
• EMA Reflection Paper on Nanomedicines
• WHO Guidelines on Evaluation of Liposomal Drug Products

9. SOP Version

Version: 2.0

10. Approval Section

	Prepared By	Checked By	Approved By
Signature
Date
Name
Designation
Department

11. Annexures

Annexure-1: Encapsulation Efficiency Log

Batch No.	Total Drug (mg)	Free Drug (mg)	Encapsulation (%)	Analyst
LPZ/2025/003	10.0	1.2	88.0%	Ajay Verma

Annexure-2: Release Profile Log

Time (hr)	Drug Released (%)	Medium	Analyst
0	0.0	PBS pH 7.4	Sunita Reddy
1	12.5	PBS pH 7.4	Sunita Reddy
2	22.0	PBS pH 7.4	Sunita Reddy

Annexure-3: Method Validation Summary

Parameter	Result	Acceptance Criteria	Status
Linearity	R² = 0.9996	R² ≥ 0.999	Pass
Accuracy	98.5%–101.2%	98%–102%	Pass

Revision History:

Revision Date	Revision No.	Details	Reason	Approved By
04/05/2025	2.0	Added in-vitro release and degradation testing sections	Annual SOP Review