Production of Hydrogel-Based Curcumin-Loaded O/W Suspoemulsions

Curcumin is a biopharmaceutical classification system (BCS) class IV substance with many potential therapeutic effects. However, like many other BCS IV active pharmaceutical ingredients, complex formulations are needed to guarantee a sufficiently high bioavailability. A not-so-well-known delivery system is a suspoemulsion (SE). SEs are emulsions with a crystalline API in continuous or dispersed phases. This study aimed to produce curcumin-loaded o/w suspoemulsions with the particle in the oil phase for, e.g., encapsulation or triggered release effects. The particles need to be smaller than the emulsion droplet size to attain high encapsulation efficiencies (EE) in the oil phase. Sonofragmentation and bead milling were tested for their ability to produce these nanocrystals in different dispersion media. It was discovered that production in miglyol was the best fit for the needed application of the crystals in SEs. Around 85% (by volume) of the particles produced with bead milling were smaller than the droplet size of about 5 µm. In contrast, only 23% of the sonofragmentated particles were below the diameter of those droplets. This oily suspension was then used to successfully produce hydrogel-based o/w suspoemulsions. In the second part of this study, we investigated different methods for determining encapsulation efficiency, but none of the methods accurately and satisfactorily resolved the encapsulation efficiency. Finally, the suspoemulsions could not be macroscopically distinguished from one another and were physically stable. In summary, we showed that stable hydrogel-based curcumin-loaded o/w suspoemulsions could be produced.