stability of the liposomes.

Quality Control (QC): Ensure that the liposomal formulations meet the required quality standards, including API encapsulation efficiency, particle size, and stability over time.

Project Managers: Coordinate the liposomal formulation development process, ensuring that the formulation is optimized for clinical use and meets project timelines.

4) Procedure

The following steps outline the procedure for incorporating APIs into liposomal formulations:

1. Step 1: Define Formulation Requirements
   1. Identify the API and evaluate its physicochemical properties (e.g., solubility, stability) to determine the most suitable incorporation method into liposomes.
   2. Define the therapeutic goal, including the desired release profile (e.g., controlled release, targeted release) and the required dose for the formulation.
   3. Select the type of liposomal formulation (e.g., conventional liposomes, pegylated liposomes, stealth liposomes) based on the intended application and the API’s characteristics.
2. Step 2: Preparation of Liposomes
   1. Prepare liposomes using one of the following methods, depending on the properties of the API and the desired formulation characteristics:
      • Thin Film Hydration: Involves dissolving the phospholipids in an organic solvent, followed by solvent evaporation and hydration to form liposomes.
      • Reverse Phase Evaporation: Used for encapsulating hydrophilic drugs by forming liposomes in a two-phase system (organic and aqueous phases) and evaporating the organic solvent.
      • Extrusion: Liposomes are extruded through filters with defined pore sizes to achieve uniform particle size.
   2. Ensure that the liposomes are properly hydrated, and check the particle size distribution to ensure uniformity and the desired size for drug delivery.
3. Step 3: Incorporation of API
   1. For Hydrophobic Drugs: Dissolve the hydrophobic API in an organic solvent (e.g., chloroform, ethanol) along with the lipids. After evaporation of the solvent, hydrate the lipid-API mixture to form liposomes, ensuring that the API is incorporated into the lipid bilayer.
   2. For Hydrophilic Drugs: Hydrate the lipid film with an aqueous solution containing the hydrophilic API. The API will be encapsulated in the internal aqueous phase of the liposome.
   3. If required, use techniques such as remote loading (e.g., using a pH gradient or ion gradient) to enhance the loading efficiency of the API into liposomes.
4. Step 4: Characterization of Liposomal Formulation
   1. Measure the encapsulation efficiency by separating unencapsulated drug from the liposomal formulation using techniques such as centrifugation or dialysis.
   2. Determine the particle size, zeta potential, and polydispersity index (PDI) using dynamic light scattering (DLS) or laser diffraction.
   3. Characterize the morphology of the liposomes using transmission electron microscopy (TEM) or scanning electron microscopy (SEM).
   4. Assess the stability of the liposomal formulation under different storage conditions (e.g., temperature, light exposure) to ensure the integrity of the liposomes over time.
5. Step 5: In Vitro Release Testing
   1. Conduct in vitro drug release studies to evaluate the release profile of the API from the liposomes under physiological conditions (e.g., using a dialysis method or Franz diffusion cell).
   2. Assess the release rate of the API from the liposomes over time, considering factors such as the liposomal formulation type and the nature of the API.
   3. Compare the release profile to the intended therapeutic goals (e.g., controlled release or sustained release). If necessary, adjust the formulation or release mechanism.
6. Step 6: Stability Studies
   1. Conduct stability studies on the liposomal formulation to assess its physical and chemical stability under various conditions (e.g., temperature, humidity, and light exposure).
   2. Monitor changes in drug content, particle size, PDI, and encapsulation efficiency during the stability testing period (e.g., at 0, 3, 6, and 12 months).
   3. Assess the potential for API leakage or degradation and evaluate the formulation’s shelf-life and storage conditions.
7. Step 7: Documentation and Reporting
   1. Document all formulation preparation steps, API incorporation methods, and characterization results, including encapsulation efficiency, particle size, and release data.
   2. Prepare a detailed report summarizing the liposomal formulation’s characteristics, in vitro release data, and stability study results.
   3. Ensure that all records are signed, dated, and stored in compliance with Good Laboratory Practices (GLP) and regulatory standards.
8. Step 8: Sample Disposal
   1. Dispose of any remaining test samples, solvents, and materials according to safety protocols and environmental regulations.
   2. Ensure that hazardous materials are disposed of in designated chemical waste containers in compliance with safety guidelines.

5) Documents

The following documents should be maintained during the incorporation of APIs in liposomal formulations:

1. Formulation Preparation Records
2. API Incorporation Records
3. Encapsulation Efficiency and Particle Size Data
4. In Vitro Release Testing Reports
5. Stability Testing Records
6. Final Liposomal Formulation Report
7. Sample Disposal Records

6) Abbreviations

• API: Active Pharmaceutical Ingredient
• GLP: Good Laboratory Practices
• HPLC: High-Performance Liquid Chromatography
• USP: United States Pharmacopeia
• PDI: Polydispersity Index

7) References

References to regulatory guidelines and scientific literature that support this SOP:

• FDA Guidance for Pharmaceutical Development
• USP <1132> on Liposomes
• ICH Q8(R2) Pharmaceutical Development

8) Version

Version 1.0: Initial version of the SOP.

9) Annexure

Liposomal Formulation Characterization Results Template

Formulation ID	Encapsulation Efficiency (%)	Particle Size (nm)	Zeta Potential (mV)	Release Profile