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Atopic dermatitis (AD) is a chronically relapsing eczematous skin disease characterised by frequent episodes of rashes, severe flares, and inflammation. Till date, there is no absolute therapy for the treatment of AD; however, topical corticosteroids (TCs) are the majorly prescribed class of drugs for the management of AD in both adults and children. Though, topical route is most preferable; however, limited penetration of therapeutics across the startum cornum (SC) is one of the major challenges for scientists. Therefore, the present study was attempted to fabricate a moderate-potency TC, betamethasone valerate (BMV), in the form of chitosan nanoparticles (CS-NPs) for optimum dermal targeting and improved penetration across the SC. To further improve the targeting efficiency of BMV and to potentiate its therapeutic efficacy, the fabricated BMV-CS-NPs were coated with hyaluronic acid (HA). The prepared NPs were characterised for particle size, zeta potential, polydispersity index (PDI), entrapment efficiency, loading capacity, crystallinity, thermal behaviour, morphology, in vitro release kinetics, drug permeation across the SC, and percentage of drug retained into various skin layers. Results showed that optimised HA-BMV-CS-NPs exhibited optimum physicochemical characteristics including finest particle size (< 300 ± 28 nm), higher zeta potential (+ 58 ± 8 mV), and high entrapment efficiency (86 ± 5.6%) and loading capacity (34 ± 7.2%). The in vitro release study revealed that HA-BMV-CS-NPs displayed Fickian diffusion-type mechanism of release in simulated skin surface (pH 5.5). Drug permeation efficiency of BMV was comparatively higher in case of BMV-CS-NPs; however, the amount of drug retained into the epidermis and the dermis was comparatively higher in case of HA-BMV-CS-NPs, compared to BMV-CS-NPs. Conclusively, we anticipate that HA-BMV-CS-NPs could be a promising nanodelivery system for efficient dermal targeting of BMV and improved anti-AD efficacy.

Response surface methodology (RSM) Central composite rotatable design (CCRD) Box-Behnken design (BBD) a b s t r a c t Box-Behnken (BBD) and central composite rotatable designs (CCRD) were used as statistical multivariate methods in the formulation optimization of fullerene loaded nano-emulsions. Effect of palm kernel oil ester (10-20%, w/w), emulsifier (5-10%, w/w) and xanthan gum (0.6-1.0%, w/w) as formulation variables on the particle size, -potential and viscosity of the nano-emulsions were investigated. Under the optimum conditions, CCRD model predicted the response values for particle size, -potential and viscosity were 153.6 nm, −53.4 mV and 42.1 Pa s, respectively. Nonetheless, BBD model suggested that the optimum conditions for a fullerene loaded nano-emulsion would gave particle size, -potential and viscosity of 151.6 nm, −53.8 mV and 43.1 Pa s, respectively. The actual response according to suggested compositions for both models showed excellent agreement with the predicted value with residual standard error (RSE) of less than 4%. Optimum nano-emulsions were stable during storage at 25 and 45 • C for 90 days and freeze-thaw cycle.

Fullerene nanoemulsions were formulated in palm kernel oil esters stabilized by low amount of mixed nonionic surfactants. Pseudoternary phase diagrams were established in the colloidal system of PKOEs/Tween 80 : Span 80/water incorporated with fullerene as antioxidant. Preformulation was subjected to combination of high and low energy emulsification methods and the physicochemical characteristics of fullerene nanoemulsions were analyzed using electroacoustic spectrometer. Oil-in-water (O/W) nanoemulsions with particle sizes in the range of 70–160 nm were formed. The rheological characteristics of colloidal systems exhibited shear thinning behavior which fitted well into the power law model. The effect of xanthan gum (0.2–1.0%, w/w) and beeswax (1–3%, w/w) in the estimation of thermodynamics was further studied. From the energetic parameters calculated for the viscous flow, a moderate energy barrier for transport process was observed. Thermodynamic study showed that the enthalpy was positive in all xanthan gum and beeswax concentrations indicating that the formation of nanoemulsions could be endothermic in nature. Fullerene nanoemulsions with 0.6% or higher xanthan gum content were found to be stable against creaming and flocculation when exposed to extreme environmental conditions.