4) Procedure

4.1 Solvent Selection

Solvent selection is an important factor in ensuring the successful formation of liposomes and emulsions. The solvent must be compatible with the lipids or emulsifiers used and should facilitate proper lipid solubilization and assembly.

4.1.1 Commonly Used Solvents

• Chloroform: A widely used solvent for dissolving phospholipids due to its ability to solubilize a wide range of lipid components.
• Methanol and Ethanol: Organic solvents that are commonly used for cholesterol and other lipid components. These solvents are miscible with water and can be used in both liposome and emulsion formulations.
• Acetone: Sometimes used in emulsion formulations for dissolving hydrophobic components. Acetone evaporates quickly and may be used in solvent evaporation methods.
• Ether: Often used for the formation of emulsions, especially for volatile emulsions. Care must be taken when using ether due to its flammability.

4.1.2 Solvent Selection Guidelines

• 4.1.2.1 Choose solvents that are compatible with the lipid components of the formulation. The solvent should be able to dissolve the lipids or emulsifiers completely and facilitate their assembly into stable liposomes or emulsions.
• 4.1.2.2 The selected solvent must be volatile enough to be easily removed during the evaporation or drying process, leaving behind no residue that could affect the formulation’s stability.
• 4.1.2.3 For liposome formulations, ensure that the solvent is non-reactive with the drug or active pharmaceutical ingredient (API) being encapsulated.
• 4.1.2.4 Consider using environmentally friendly and less toxic solvents whenever possible. If using hazardous solvents, ensure proper safety protocols are in place.

4.2 Solvent Handling and Safety

Due to the volatile and often hazardous nature of organic solvents, strict safety guidelines must be followed during handling and storage. The following precautions are mandatory when working with solvents in liposome and emulsion formulations:

4.2.1 Personal Protective Equipment (PPE)

Before handling any solvent, ensure that the following PPE is worn:

• 4.2.1.1 Nitrile or neoprene gloves, which provide protection against organic solvents.
• 4.2.1.2 Safety goggles to protect the eyes from splashes.
• 4.2.1.3 Lab coats or aprons to protect clothing and skin from spills.
• 4.2.1.4 Face masks or respirators if working with volatile or toxic solvents in non-ventilated areas.

4.2.2 Solvent Handling Procedure

• 4.2.2.1 Always work with solvents in a fume hood or a well-ventilated area to prevent the buildup of vapors.
• 4.2.2.2 Transfer solvents using appropriate glassware, such as glass beakers or bottles with solvent-resistant lids. Never use plastic containers for solvent storage or handling unless they are specifically rated for the solvent.
• 4.2.2.3 Avoid open flames or sparks when working with flammable solvents, and ensure that all electrical equipment is explosion-proof if working in areas where solvent vapors may be present.
• 4.2.2.4 When mixing solvents with lipids or emulsifiers, add the solvent gradually while stirring to ensure proper mixing and to minimize the risk of splashes.
• 4.2.2.5 After handling solvents, dispose of gloves and other contaminated PPE in designated hazardous waste containers. Wash hands thoroughly after removing gloves.

4.2.3 Storage of Solvents

Solvents must be stored in a designated, ventilated area that meets regulatory requirements for the storage of flammable and hazardous materials.

• 4.2.3.1 Store solvents in their original containers with proper labeling, including the solvent name, hazard symbols, and safety instructions.
• 4.2.3.2 Keep solvents in flame-proof cabinets, away from sources of ignition and extreme temperatures.
• 4.2.3.3 Check solvent containers regularly for leaks or corrosion. Replace any damaged containers immediately to prevent spills or accidents.
• 4.2.3.4 Maintain an updated inventory of all solvents, including their locations and expiration dates, to facilitate proper stock management.

4.3 Solvent Disposal

Improper disposal of solvents can lead to environmental contamination and safety hazards. The following steps should be followed for the disposal of solvents:

4.3.1 Disposal Guidelines

• 4.3.1.1 Collect all used solvents in designated waste containers labeled “Hazardous Waste.” Ensure that the waste containers are chemically compatible with the solvents being disposed of.
• 4.3.1.2 Store waste solvent containers in a designated hazardous waste storage area until they can be disposed of by an approved waste disposal service.
• 4.3.1.3 Do not pour solvents down the drain or discard them in regular trash bins. Follow local regulations and company protocols for hazardous waste disposal.
• 4.3.1.4 Keep records of solvent disposal activities, including the type and volume of solvents disposed of, disposal dates, and the waste disposal contractor’s details.

5) Abbreviations, if any

• PPE: Personal Protective Equipment
• API: Active Pharmaceutical Ingredient

6) Documents, if any

• Solvent Inventory Log
• Equipment Calibration Log
• Solvent Waste Disposal Log (Annexure 1)

7) References, if any

• OSHA Guidelines for Safe Handling of Organic Solvents
• ICH Q7: Good Manufacturing Practice Guide for Active Pharmaceutical Ingredients
• FDA Guidelines for Solvent Selection and Use in Drug Formulation

8) SOP Version

Version 1.0

Annexure

Annexure 1: Solvent Waste Disposal Log Template

  

    
Date
    
Solvent Name
    
Volume (L)
    
Waste Container ID
    
Disposal Method
    
Operator Initials
  
  

    
DD/MM/YYYY
    
Solvent Name
    
Volume in Liters
    
Waste Container ID
    
Recycling/Incineration
    
Operator Name