Limonene-based Self-nanoemulsifying System: Formulation, Physicochemical Characterization and Stability

Objectives: The aim of current research was to formulate limonene selfnanoemulsified delivery system (SNEDS) by spontaneous emulsification method. Methods: The optimization was carried out through the construction of a pseudo-ternary phase diagram. Limonene-based self- nanoemulsifying system was optimized by evaluating its droplet characteristic; namely; size, polydispersity, zeta potential, in addition, its morphology was assessed through the use of transmission electron microscopy. Moreover, the formulation stability under different storage conditions for three months was examined. Results: The obtained results showed that the optimized limonene-based self-nanoemulsifying system was characterized by a small droplet size, low polydispersity index, high percentage transmittance and optimal zeta potential with uniform spherical droplets. The selected formulation with 50% w/w limonene, 40% w/w Tween 80 and 10% w/w propylene glycol had a droplet size of 113.3±1.18nm with bluish transparent appearance and a zeta potential value of -19.13±0.38 mV. The developed formula was stable against pH change. The stored limonenebased SNEDS showed acceptable stability at 4°C and 0°C compared to 25°C. Conclusion: The formulated self-nanoemulsifying system showed an improved aqueous dispersibility, patient acceptability and stability of limonene, representing a promising carrier for lipophilic drugs.