4.2 Weighing and Preparation of Lipid Components

Accurate weighing and preparation of lipid components are essential for the consistency of liposome formulations. Follow the steps below to prepare the lipid components:

4.2.1 Weighing Lipids

• 4.2.1.1 Tare the analytical balance before weighing each lipid component.
• 4.2.1.2 Weigh the lipids according to the formulation requirements (e.g., phospholipids, cholesterol).
• 4.2.1.3 Record the weight of each lipid in the Batch Manufacturing Record (BMR, see Annexure 1).
• 4.2.1.4 Ensure that the lipids are handled with care to avoid contamination or moisture absorption.

4.2.2 Dissolving Lipids

Lipids must be dissolved in an appropriate solvent to achieve a uniform lipid film. The solvent selection is critical and depends on the specific lipids being used.

• 4.2.2.1 Transfer the weighed lipids into a clean glass beaker.
• 4.2.2.2 Add the appropriate solvent (e.g., chloroform, methanol) in the required volume. The solvent must be dry and of analytical grade.
• 4.2.2.3 Stir the solution using a magnetic stirrer until the lipids are completely dissolved. This may take 10-30 minutes depending on the lipid type.
• 4.2.2.4 Maintain a gentle heat on the hot plate, if necessary, to aid dissolution, but do not exceed 40°C to avoid lipid degradation.

4.3 Lipid Film Formation

Once the lipids are fully dissolved, a lipid film must be created as part of the liposome formation process. This is typically done using a rotary evaporator, but a simple evaporation method can also be employed for small-scale operations.

4.3.1 Evaporation Process

• 4.3.1.1 Pour the dissolved lipids into a round-bottom flask.
• 4.3.1.2 Set up the rotary evaporator or vacuum pump to evaporate the solvent under reduced pressure.
• 4.3.1.3 Rotate the flask slowly to ensure even distribution of the lipid film across the inner surface of the flask.
• 4.3.1.4 Continue the evaporation process until a thin, dry lipid film forms on the flask wall. This can take approximately 1-2 hours depending on the solvent used.
• 4.3.1.5 Ensure that no residual solvent remains in the flask. If necessary, apply gentle heating (<40°C) to remove any remaining solvent traces.

4.4 Storage of Lipid Films

The lipid film can be stored for future use in liposome formulations. The storage conditions must prevent lipid degradation and oxidation.

• 4.4.1 After film formation, allow the lipid film to cool to room temperature.
• 4.4.2 Once cooled, the lipid film can be sealed with parafilm or transferred into an air-tight container.
• 4.4.3 Store the lipid film under an inert atmosphere (e.g., nitrogen or argon) in a desiccator or a temperature-controlled environment, typically at -20°C or below.
• 4.4.4 Label the containers with the lipid name, batch number, preparation date, and expiration date.

4.5 Handling Precautions

Lipids are sensitive to oxidation and degradation. To maintain the integrity of lipid components:

• 4.5.1 Minimize the exposure of lipids to air and light.
• 4.5.2 Always handle lipids in an inert atmosphere or a controlled environment, such as a glove box or fume hood.
• 4.5.3 Wear appropriate personal protective equipment (PPE), including gloves and lab coats, when handling lipids and solvents.

5) Abbreviations, if any

• PPE: Personal Protective Equipment
• BMR: Batch Manufacturing Record
• QC: Quality Control

6) Documents, if any

• Batch Manufacturing Record (BMR, see Annexure 1)
• Equipment Calibration Log

7) References, if any

• FDA Guidelines for Lipid-Based Drug Formulations
• International Conference on Harmonisation (ICH) Q7: Good Manufacturing Practice Guide for Active Pharmaceutical Ingredients

8) SOP Version

Version 1.0

Annexure

Annexure 1: Batch Manufacturing Record Template

  

    
Batch No.
    
Lipid Component
    
Weight
    
Solvent
    
Dissolution Time
    
Operator Initials
    
QA Signature
  
  

    
Batch Number
    
Lipid Name
    
Weight in grams
    
Solvent Name
    
Minutes
    
Operator Name
    
QA Name