Formulation and stability evaluation of honey-loaded nanoemulsion for topical delivery

Background and objectives

Honey is a viscous, hygroscopic liquid in nature. It has the ability to treat wounds, wrinkles, aging, and inflammation. This study's objective was to create and characterize a nanoemulsion containing honey and evaluate its stability.

Methods

A pseudo-ternary phase diagram was retraced with several concentrations of the Smix, water, and liquid paraffin oil to formulate nanoemulsions containing honey. From the results of pre-formulation stability studies, formulation HNE-19, with a hydrophilic lipophilic balance value of 10, and a surfactant and oil ratio of 1:1, was selected as the most stable formulation. HNE-19 and base (B-19) were further subjected to thermodynamic studies of heating and cooling cycles and centrifugation. HNE-19 and its respective base B-19 were characterized for physical changes, droplet size analysis, pH measurements, turbidity, viscosity, and rheological parameters for a period of 90 days.

Results

Results showed that the nanoemulsion containing honey was clear and milky white. There was no evidence of phase separation in HNE-19 and B-19 after the thermodynamic study. The droplet size of fresh HNE-19 was 91.07 nm with a zeta potential of −38.5 mV. After three months, the droplet size and zeta potential were 197.06 nm and −32.5 mV respectively. The observed pH was between 5.8 and 6.7, which corresponds with the pH of the skin. HNE-19 showed non-Newtonian flow and pseudo-plastic behavior.

Conclusions

A honey-loaded nanoemulsion (HNE-19) was successfully developed and characterized for stability. The nanoemulsion was thermodynamically stable. With the good rheology and stability of honey, the size of the nanodroplets was below 200 nm. Throughout the 90-day testing period, the nanoemulsion maintained normal pH values that corresponded to skin pH. The emulsion also showed non-Newtonian flow and pseudo-plastic behavior, which are required for ideal topical formulation. In conclusion, stability studies and characterization showed that nanoemulsions containing honey are exceptional topical delivery formulations.