uptake in the brain was observed for IV-administered paclitaxel-containing SLNs. Here, the avoidance of capture by liver and spleen macrophages was achieved by the low surface hydrophobicity of the particles. Further, the efficacy of paclitaxel in SLNs was found to be 100-fold greater than free paclitaxel on MCF-7 cells, while on HL60 cells, a lower sensitivity was achieved with paclitaxel in SLNs [33]. It could be shown for camptothecin that an increased uptake was found in the brain [34]. This can be explained by the adsorption of blood proteins such as ApoE which mediates the adherence to the endothelial cells of the blood brain barrier.

Camptothecin is also an example of orally delivered SLN formulations [35]. It was demonstrated that the drug was effectively protected from hydrolysis, and that in vitro sustained release was achieved for up to a week. Another example for successful oral drug delivery is cyclosporine A. In vitro, a pseudozero order was determined [36]; in an in vivo study with pigs, it was found that prolonged release with low variations in the blood levels was possible [37].

For dermal administration, it can be shown that the incorporation of molecular sunscreens leads to improved protection levels due to a decrease in penetration into the skin [32]. This was achieved by producing SLNs with a drug-enriched core. For coenzyme-Q10-containing SLNs, increased skin penetration, and thus increased effects, can be achieved by formulating the drug-enriched shell type. Furthermore, the chemically labile drug can be stabilized by incorporation into the protective solid matrix [38].

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