The use of doxorubicin (DOX), one of the most effective antitumor molecules in the treatment of metastatic breast cancer, is limited by its low tumor selectivity and its severe side effects. Colloidal carriers based on biodegradable poly(butylcyanoacrylate) nanoparticles (PBCA NPs) may enhance DOX antitumor activity against breast cancer cells, thus allowing a reduction of the effective dose required for antitumor activity and consequently the level of associated toxicity. DOX loading onto PBCA NPs was investigated in this work via both drug entrapment and surface adsorption. Cytotoxicity assays with DOX-loaded NPs were performed in vitro using breast tumor cell lines (MCF-7 human and E0771 mouse cancer cells), and in vivo evaluating antitumor activity in immunocompetent C57BL/6 mice. The entrapment method yielded greater drug loading values and a controlled drug release profile. Neither in vitro nor in vivo cytotoxicity was observed for blank NPs. The 50% inhibitory concentration (IC 50 ) of DOX-loaded PBCA NPs was significantly lower for MCF-7 and E0771 cancer cells (4 and 15 times, respectively) compared with free DOX. Furthermore, DOX-loaded PBCA NPs produced a tumor growth inhibition that was 40% greater than that observed with free DOX, thus reducing DOX toxicity during treatment. These results suggest that DOX-loaded PBCA NPs have great potential for improving the efficacy of DOX therapy against advanced breast cancers.

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Different studies have attributed health benefits to Lactobacillus fermentum CECT 5716. However, the main problem associated with probiotics is their low resistance to environmental and technological factors. In this sense, capsules can provide a shell protection and a dosage form that is easy to swallow. For these reasons, the aim of this study was to evaluate the survival of Lactobacillus fermentum CECT 5716 in gelatin and gastro-resistant capsules during a period of 12 months at RT (room temperature) and 4 °C. The number of encapsulated cells remained relatively constant after six months of storage, since there were no statistically significant differences compared to the initial time (p > 0.05). Moreover, capsules are able to maintain a therapeutic level of bacteria (10 9 CFU/capsule) during the total period of storage. Gelatin capsules seem to protect worse probiotic than gastro-resistant (HPMC (hydroxy propyl methyl cellulose)) capsules. Furthermore, capsules stored at 4 °C show a low level of viability. These results suggest that HPMC capsules are an optimal dosage form for L. fermentum CECT 5716 and that the recommended condition of storage is room temperature rather than 4 °C.