Formulation and evaluation of a vitamin C multiple emulsion

Area of Science:

• Cosmetic Science
• Materials Science
• Physical Chemistry

Background:

• Multiple phase emulsions offer advantages over simple emulsions, including controlled ingredient release and enhanced cosmetic properties.
• Vitamin C (ascorbic acid) is a valuable skincare ingredient for its moisturizing and anti-aging effects, but its topical application is limited by instability, particularly oxidation.
• Incorporating unstable active ingredients like vitamin C into stable delivery systems is crucial for effective skincare formulations.

Purpose of the Study:

• To investigate the stability and release profile of vitamin C (ascorbic acid) incorporated into oil-in-water-in-oil (O/W/O) multiple emulsions.
• To evaluate the impact of various formulation parameters, including surfactant types, ratios, and phase volumes, on vitamin C stability and release kinetics.
• To compare the performance of O/W/O multiple emulsions with simple oil-in-water (O/W) emulsions for vitamin C delivery.

Main Methods:

• Formulation of O/W/O multiple emulsions using a two-step procedure with varying surfactant systems (non-ionic siliconized, sorbitan derivatives, polyglyceryl derivatives) and phase ratios.
• Evaluation of physical stability through microscopic examination, centrifugation, and temperature incubation.
• In vitro release studies using Franz diffusion cells and UV spectrophotometry to determine vitamin C release kinetics.

Main Results:

• Stable O/W/O emulsions containing vitamin C were successfully prepared using specific non-ionic siliconized surfactants, sorbitan derivatives, and co-surfactants.
• Vitamin C exhibited significantly increased stability within the O/W/O multiple emulsion system, attributed to entrapment within reverse micelles.
• In vitro release studies demonstrated a slow and controlled release of vitamin C from O/W/O emulsions, following zero-order kinetics, with approximately 14% released in the first four hours.

Conclusions:

• O/W/O multiple emulsions provide an effective delivery system for enhancing the stability of vitamin C (ascorbic acid) in cosmetic formulations.
• The unique structure of multiple emulsions, potentially involving reverse micelles, protects vitamin C from degradation and enables a zero-order, controlled release profile.
• These findings suggest that multiple emulsions are a promising strategy for developing advanced skincare products with improved efficacy and stability of active ingredients like vitamin C.