Pseudo-ternary Phase Diagrams for Lipid Formulation

Purpose: Lipid-based formulations are frequently studied as they improve oral bioavailability of water-insoluble drugs that constitute 40% of new drugs. A pseudo-ternary diagram is a thesaurus tool used to define a specific physical composition of a thermodynamically stable solution. The aim of this study was to construct phase diagrams of lipid-based formulations that could be used for identifying optimum compositions for drug delivery. Method: The aqueous titration experimental method was used. A lipid, including oleic acid and Miglyol 812, and a surfactant, including Cremophor EL, Tween 80 and TPGS, were mixed in a fixed ratio. No co-surfactant was used. The mixture was heated at 45°C. Water was used as a titer and was added in increment of 5%-10% to up to 95% of the total mixture. After equilibrium, the mixture was observed for characterization. Data were gathered on a table, showing each increment of water, the amount of each component, and the percentage of each component in the mixture. The pseudo-ternary phase diagrams were constructed. Result: All phase diagrams have various areas of emulsion and microemulsion. Comparing sets of phase diagrams, Miglyol and TPGS produced the largest areas of one continuous phase. Oleic acid and TPGS produced a large area of emulsion. Conclusion: The pseudo-ternary phase diagrams of one lipid and one surfactant were constructed by using a titration method. Miglyol and TPGS form stable binary systems that could be used for further formulation development.