SOP for Preparation of Liposomes using Extrusion Method

Preparation of Liposomes using Extrusion Method

1) Purpose

This SOP describes the preparation of liposomes using the extrusion method. The extrusion technique is used to reduce liposome size and achieve uniform size distribution. Liposomes are passed through membrane filters under pressure, resulting in small unilamellar vesicles (SUVs) with consistent size and characteristics.

2) Scope

This SOP applies to all personnel involved in the preparation of liposomes using the extrusion method. It covers the steps for setting up the extruder, preparation of the lipid and aqueous phases, and size reduction through extrusion.

3) Responsibilities

Operators: Responsible for executing the extrusion procedure according to this SOP, ensuring proper calibration and cleaning of the extruder.
QA Team: Responsible for ensuring that the extrusion process is conducted as per quality standards, verifying procedures, and reviewing batch records.
QC Team: Responsible for conducting quality control tests to confirm the size, stability, and encapsulation efficiency of the prepared liposomes.

4) Procedure

4.1 Equipment Setup

Before beginning the extrusion process, ensure that all equipment is cleaned, calibrated, and set up correctly.

4.1.1 Required Equipment

Extruder with polycarbonate membrane filters (100 nm or desired pore size)
High-pressure nitrogen or air source
Magnetic stirrer
Rotary evaporator
pH meter
Temperature-controlled water bath

4.1.2 Equipment Calibration

4.1.2.1 Ensure the extruder pressure settings are calibrated

correctly and that the membrane filters are intact.

4.1.2.2 Verify that the pH meter is calibrated with standard buffer solutions (pH 4.0, 7.0, and 10.0) before use.

4.1.2.3 Confirm that the water bath is functioning correctly and can maintain the required temperature for the lipid hydration process.

4.2 Lipid Film Preparation

The lipids must be dissolved, and the organic solvent must be evaporated to form a thin lipid film. This will later be hydrated and extruded to form liposomes.

4.2.1 Weigh the required amount of lipid components according to the formulation protocol and record the weights in the Batch Manufacturing Record (BMR).
4.2.2 Dissolve the lipids in an appropriate organic solvent (e.g., chloroform, ethanol) in a round-bottom flask.
4.2.3 Evaporate the solvent using a rotary evaporator to form a thin lipid film.
4.2.4 Dry the lipid film under vacuum for 30 minutes to remove residual solvent.

4.3 Hydration of Lipid Film

The lipid film is hydrated using an aqueous phase, such as a buffer solution or drug solution, to form multilamellar vesicles (MLVs).

4.3.1 Add the pre-warmed aqueous phase to the round-bottom flask containing the lipid film.
4.3.2 Stir the mixture for 30 minutes to ensure complete hydration of the lipid film.
4.3.3 Adjust the pH of the aqueous phase using a calibrated pH meter to ensure stability of the liposomes and the encapsulated compound.

4.4 Extrusion Process

The multilamellar liposome suspension is passed through polycarbonate membrane filters under pressure to produce unilamellar liposomes of uniform size.

4.4.1 Transfer the hydrated lipid suspension to the extruder inlet.
4.4.2 Apply pressure using nitrogen or air, and pass the suspension through polycarbonate membranes with a pore size of 100 nm or the desired size.
4.4.3 Repeat the extrusion process 5 to 10 times to ensure uniform size reduction and consistency.
4.4.4 Collect the extruded liposome suspension in a clean, sterile container.

4.5 Quality Control

Once the extrusion process is complete, perform the following quality control tests:

4.5.1 Measure the particle size of the liposomes using dynamic light scattering (DLS).
4.5.2 Test the encapsulation efficiency of the liposomes by measuring the concentration of the encapsulated drug or compound.
4.5.3 Monitor the stability of the liposomes by storing them under the specified conditions and assessing size and morphology over time.

5) Abbreviations, if any

MLV: Multilamellar Vesicle
DLS: Dynamic Light Scattering
SUV: Small Unilamellar Vesicles
QA: Quality Assurance
QC: Quality Control

6) Documents, if any

Batch Manufacturing Record (BMR)
Particle Size Analysis Report
pH Meter Calibration Log

7) References, if any

FDA Guidelines for Liposomal Drug Products
ICH Q7: Good Manufacturing Practice Guide

8) SOP Version

Version 1.0

Annexure

Annexure 1: Batch Manufacturing Record Template


  
    Batch No.
    Lipid Type
    Weight
    Solvent
    Aqueous Phase
    Extrusion Passes
    Operator Initials
    QA Signature
  
  
    Batch Number
    Lipid Name
    Weight in grams
    Solvent Name
    Buffer/Drug Solution
    Number of Passes
    Operator Name
    QA Name

Batch No.	Lipid Type	Weight	Solvent	Aqueous Phase	Extrusion Passes	Operator Initials	QA Signature
Batch Number	Lipid Name	Weight in grams	Solvent Name	Buffer/Drug Solution	Number of Passes	Operator Name	QA Name