Development of Ficus religiosa extract-loaded emulsion system for topical application: Characterization and stability evaluation

Purpose: To develop, optimize and characterize a topical (W/O) emulsion containing 4 % Ficus religiosa extract for cosmeceutical purposes. Methods: The ethanol extract of Ficus religiosa was obtained by Soxhlet method. Various formulations were developed using paraffin oil, emulsifier (Abil®-EM 90) and purified water at different proportions, and their physical stability was assessed under different stress conditions, to enable selection of the most stable formulation. The optimized formulation based on stability studies was chosen for evaluation of different physical properties, i.e., color, liquefaction, phase separation, centrifugation, pH, droplet size and rheology, under accelerated conditions for 12 weeks. Results: The optimized formulation (F4) contained ethanol extract (4.0 %), Abil®-EM 90 (3.5 %), paraffin oil (14.0 %) and purified water (78.5 %), and remained stable on centrifugation under all stress conditions. The pH of the formulation remained within the specified range for human skin pH i.e. 4.5 – 6.0, and droplet size of dispersed phase also persisted within the size range of macroemulsion (1 – 100 μm) throughout the study period. Rheological properties of the formulation showed shear thinning response, and flow index value less than 1 resulted in pseudoplastic flow of emulsion. Conclusion: These results suggest that the optimized emulsion system was stable and can serve as a good medium for topical delivery of various natural substances.