Formulation, optimization and characterization of ibuprofen loaded microemulsion system using d-optimal mixture design

Abstract

Objective: The purpose of this study was to develop, optimize and characterize a stable microemulsion, with an improvement of the solubility of a poorly aqueous soluble drug, ibuprofen. Methods: Various oils (oleic acid, cottonseed oil, olive oil, argan oil, and labrafac® WL 1349), surfactants (tween® 80, tween® 40, tween® 20) and co-surfactants including polyethylene glycol 400, ethanol, 1-butanol, and propylene glycol were selected after solubility studies. Then, pseudo-ternary phase diagrams with surfactant/co-surfactant ratio of 1:2, 1:1, 2:1 and 3:1 were constructed and a D-optimal mixture design method was used to optimize the ibuprofen loaded microemulsion. The optimized microemulsion was evaluated for several characteristics including globule size, zeta potential, pH, conductivity, refractive index and stability studies. Results: Optimized microemulsion obtained was composed of oleic acid (6.88% w/w), tween® 80/1-butanol (3:1, 63.11% w/w) and water (30.00% w/w). The results obtained showed an average globule size of 117.5 nm, a zeta potential of-6.47 mV and a transmittance of 96.95±0.77%. The optimized formulation showed an improvement in the solubility of ibuprofen with unchanged characteristics for one month. Conclusion: The use of pseudo-ternary phase diagrams and mathematical modeling allows to obtain an optimal microemulsion with perfect stability for 1 mo and a better solubilization capacity of ibuprofen.