Definition of Microemulsions:
- Microemulsions are thermodynamically stable, transparent or translucent emulsions composed of oil, water, surfactant, and co-surfactant.
Key Features:
- Droplet size: 10–100 nm
- High clarity (may appear clear or slightly bluish)
- Spontaneous formation (with gentle mixing)
- High stability compared to conventional emulsions
Types:
- O/W microemulsion
- W/O microemulsion
- Bicontinuous microemulsions
Components
- Oil phase: Medium-chain triglycerides, isopropyl myristate
- Surfactants: High HLB (e.g., polysorbates)
- Co-surfactants: Alcohols like ethanol, propylene glycol (reduce interfacial tension further)
Advertisements
Advantages in Pharmaceutics:
- Enhanced drug solubility
- Improved bioavailability
- Rapid absorption
- Suitable for oral, topical, and parenteral use
Formulation Requirements:
- Use of high concentrations of surfactants and co-surfactants (e.g., alcohols)
- Specific oil-to-surfactant ratios
