Exploration of Microneedle-assisted skin delivery of cyanocobalamin formulated in ultraflexible lipid vesicles.

Vitamin B12 (cyanocobalamin) deficiency is a widespread condition because of its different aetiologies, like malabsorption syndrome or lifestyles as strict veganism that is increasing its incidence and prevalence in developed countries. It has important haematological consequences that require pharmacological treatment. Current therapy consists of oral or parenteral supplements of cyanocobalamin; however, the oral route is discarded for malabsorption syndrome patients and the parenteral route is not well accepted generally. Topical treatments have been suggested as an alternative, but the molecular weight and hydrophilicity of cyanocobalamin limits its diffusion through the skin. Lipid vesicles can allow the transdermal absorption of molecules > 500 Da. The aim of this work was to use different ultraflexible lipid vesicles (transfersomes and ethosomes) to enhance cyanocobalamin transdermal delivery. Vesicles were characterized and lyophilised for long-term stability. The ability to deliver cyanocobalamin through the skin was assessed in vitro using full-thickness porcine skin in Franz diffusion cells. As expected, the best transdermal fluxes were provided by ultraflexible vesicles, in comparison to a drug solution. Moreover, the pre-treatment of the skin with a solid microneedle array boosts the amount of drug that could potentially reach the systemic circulation.

Targeted delivery of Cyclosporine A by polymeric nanocarriers improves the therapy of inflammatory bowel disease in a relevant mouse model.

The therapy of inflammatory bowel diseases is still rather inefficient, and about 80% of patients require surgery at some stage. Improving the treatments by more efficient medication is, therefore, an urgent medical need. The objective of this project was to demonstrate targeted delivery of Cyclosporine-A (CYA) to the inflamed areas of the intestinal mucosa after oral administration, enabling improved alleviation of the symptoms and, at the same time, reduced systemic drug absorption and associated adverse effects. As had already been demonstrated in previous studies, nano- to micrometer-sized drug particles will accumulate at inflamed mucosal areas, providing a platform for such purposes. CYA as incorporated in poly-(lactic-co-glycolic-Acid) (PLGA) nano- and mirocarriers, respectively, each homogeneous in size and providing controlled drug release over 24h at intestinal pH-value. For comparative reasons, a commercial formulation (Sandimmun Neoral®) was included in the study. In an acute model of DSS-induced inflammation in Balb/c mice, up to three doses were administered for each formulation: 50mg/kg, 25mg/kg and 12.5mg/kg. Drug-free particles were included as control. The following parameters were evaluated: body weight, colon length, colon weight/length ratio, cytokine expression and histological analysis. Plasma levels of CYA were analysed to compare systemic bioavailability. While disease parameters, such as, e.g. colon length, always improved with an optimum dose of 25mg/kg, the commercial and the microparticulate formulations led to measurable plasma levels and adverse effects in terms of body weight loss at the highest dose. In contrast, when administering the same doses as nanoparticles, plasma concentrations remained always below the detection limit, and the body weight of the animals remained unchanged. In conclusion, this study corroborates the potential of nanocarriers enabling an improved topical delivery of CYA to the inflamed gut mucosa after oral administration yielding the same improvement of disease parameters at only half the dose in comparison to microparticles and a commercial oral formulation, respectively, and at the same time minimizing systemic exposure and associated adverse effect.