4.2 Preparation of Oil-in-Water Emulsion

The following steps describe the process for preparing O/W emulsions, from selecting ingredients to forming the emulsion:

4.2.1 Selection and Weighing of Ingredients

• 4.2.1.1 Weigh the required amounts of oil phase ingredients (e.g., oils, lipids) and water phase ingredients (e.g., water, hydrophilic components) according to the formulation protocol. Record the weights in the Batch Manufacturing Record (BMR).
• 4.2.1.2 Select the appropriate emulsifier(s) based on the emulsion type and stability requirements. Hydrophilic emulsifiers with a high hydrophilic-lipophilic balance (HLB) value (typically 8-18) are used for O/W emulsions.

4.2.2 Preparation of Oil and Water Phases

• 4.2.2.1 Heat the oil phase ingredients (e.g., oils, waxes) in a temperature-controlled water bath to 60°C-80°C to melt and homogenize them.
• 4.2.2.2 Heat the water phase ingredients (e.g., water, glycerin) in a separate beaker to the same temperature as the oil phase.
• 4.2.2.3 Dissolve the emulsifier(s) in the appropriate phase (usually the water phase) according to the formulation protocol.

4.2.3 Formation of the Emulsion

• 4.2.3.1 Slowly add the oil phase to the water phase while continuously mixing with a high-shear mixer.
• 4.2.3.2 Maintain the mixing speed as per the formulation protocol, and mix until a stable, coarse emulsion is formed.
• 4.2.3.3 Once the coarse emulsion is formed, pass the mixture through a homogenizer to reduce the droplet size and improve the emulsion’s stability and uniformity.

4.3 Quality Control Testing of O/W Emulsion

After the emulsion is prepared, it must undergo quality control testing to ensure that it meets the required specifications for droplet size, stability, and homogeneity. Perform the following tests:

• 4.3.1 Measure the droplet size of the emulsion using a particle size analyzer to confirm that the droplet size is within the desired range (typically 100 nm to 10 μm).
• 4.3.2 Evaluate the stability of the emulsion by monitoring for phase separation or creaming over time. Store the emulsion at room temperature and accelerated conditions to assess its stability.
• 4.3.3 Check the pH of the emulsion using a calibrated pH meter to ensure that it is within the acceptable range for the intended product (e.g., pH 4.5-7.5).
• 4.3.4 Perform viscosity measurements to ensure that the emulsion has the appropriate flow properties for its intended application (e.g., topical creams or liquid emulsions).

4.4 Storage of Oil-in-Water Emulsion

The emulsion should be stored under appropriate conditions to maintain its stability. Transfer the emulsion to sterilized, airtight containers, and label each container with the batch number, preparation date, and storage conditions. Store the emulsion at the recommended temperature (e.g., 4°C or room temperature), and periodically test its stability over time.

5) Abbreviations, if any

• O/W: Oil-in-Water
• HLB: Hydrophilic-Lipophilic Balance
• QA: Quality Assurance
• QC: Quality Control

6) Documents, if any

• Batch Manufacturing Record (BMR)
• Particle Size Analysis Report
• Stability Test Report
• pH Calibration Log

7) References, if any

• ICH Q7: Good Manufacturing Practice Guide
• FDA Guidelines for Emulsions

8) SOP Version

Version 1.0

Annexure

Annexure 1: Batch Manufacturing Record Template

  

    
Batch No.
    
Oil Phase
    
Water Phase
    
Emulsifier Type
    
Mixing Time
    
Homogenization Time
    
Operator Initials
    
QA Signature
  
  

    
Batch Number
    
Oil Type/Weight
    
Water Type/Volume
    
Emulsifier Name
    
Minutes
    
Minutes
    
Operator Name
    
QA Name