Cubosomal Betamethasone-Salicylic Acid Nano Drug Delivery System for Enhanced Management of Scalp Psoriasis.

Introduction: Betamethasone dipropionate (BD), a potent corticosteroid, and salicylic acid (SA), a keratolytic agent, have been used in combination to treat scalp psoriasis; however, undesirable side effects associated with their prolonged topical use are inevitable. In this study, BD and SA were loaded into cubosomes, a nanoparticulate system with outstanding biocompatibility, bio-adhesivity and penetration power. Methods: Design of experiments (DOE) was utilized to prepare thirteen different cubosomal dispersions by emulsification technique using glycerol monoolein (GMO) as a lipid phase and Poloxamer 407 (P407) as a surfactant, sodium carboxymethyl cellulose (SCMC) was added to enhance the dispersions' rheological properties. The thirteen dispersions were in-vitro characterized for their particle size, polydispersity index (PDI), zeta potential, BD and SA content and rheological behaviour. The desirability of an optimized formula (OF) was set to the smallest particle size, lowest zeta-potential and highest viscosity. The OF was in-vitro characterized for the same parameters in addition to transmission electron microscope imaging and in-vitro drug release. The OF's anti-psoriatic activity was evaluated in-vivo using an imiquimod-induced psoriasis model. Results: The OF achieved a particle size of 197.4 ± 9.47 nm, a PDI of 0.443 ± 0.025, a zeta potential of -44.4 ± 0.141mv, BD content of 105.85 ± 2.290%, SA content of 88.855 ± 2.920% with shear-thinning rheological behaviour and completed in-vitro drug release within 2-3 hours. The in-vivo studies confirmed the cubosomes' higher anti-psoriatic efficacy over the commercial product with lower changes in ear thickness, spleen to body weight ratio, psoriasis area severity index score and improved histopathological findings. Conclusion: The developed BD SA-loaded cubosomes exhibit promising anti-psoriatic activity attributed to its nano-size and unique lipid content, with enhanced skin penetration and modified rheological properties; increasing the formulation's in-contact duration with the scalp resulting in lower application frequency and thus reduced BD and SA associated side effects.