Formulation and Evaluation of O/W Nanoemulsions of Caffeic Acid

Objective: To Formulate and Evaluate Nanoemulsions of Caffeic acid to overcome its poor aqueous solubility and bioavailability. Methods: The caffeic acid nanoemulsions were prepared by spontaneous emulsification method through selection of oil phase based on solubility studies and surfactant and co-surfactant screening on the basis of their emulsification ability. The components were selected on the basis of maximum solubility of caffeic acid in various media such as isopropyl myristate as oil phase, tween 80 as surfactant and PEG 600 as co-surfactant. Pseudo-ternary phase diagrams were constructed to optimize the percentage of oil, surfactant and co-surfactant. The prepared nanoemulsions were then evaluated for its surface morphology, zeta potential, droplet size, pH, viscosity and drug content. Result: The formulated nanoemulsion showed -0.0468 mV zeta potential with droplet size below 100 nm, pH 5.9 and viscosity 9.3 cps. The in-vitro drug release studies showed 98.76% drug release in 0.1N HCl while 98.57% in phosphate buffer (pH 6.8) that was found to be significantly higher than that of drug. Conclusion: The formulated nanoemulsions of caffeic acid showed improvement in solubility leading to enhanced oral bioavailability.