Optimization of topical curcumin spanlastics for melanoma treatment

The aim of the study was to enhance curcumin skin permeability through the preparation of spanlastics. Spanlastics were prepared using the ethanol injection technique through a central composite design using Span 60 concentration (X₁), edge activator type (X₂), and its concentration (X₃) as the independent variables. The spanlastics were characterized for particle size (PS), encapsulation efficiency (EE), and dissolution efficiency (%DE_24h). Formulae with the highest desirability (FN1 and FN2) were prepared and further characterized. They were elastic, spherical, nonirritant, and compatible with the used excipients. They had particle sizes of 147 and 198 nm, encapsulation efficiencies of 84.00% and 89.63%, zeta potential values of -45.50 and -39.10 mV, permeation enhancement ratios of 11.51 and 8.34 folds, and amounts retained of 7.25 and 10.44 µg/cm² after 24 h, respectively. Formulae FN1 and FN2 showed cytotoxic effects after 48 h on human melanoma A375 with IC50 of 10.9 and 75.6 μg/mL, respectively. They increased the apoptotic effect confirming the success of the spanlastics to be a potential delivery for melanoma treatment.