Synthesis and release behavior of layered double hydroxides-carbamazepine composites.

Carbamazepine (CBZ) was incorporated into layered double hydroxides (LDH) to be used as a controlled drug system in solid tumors. CBZ has a formal charge of zero, so its incorporation in the anionic clay implies a challenge. Aiming to overcome this problem, CBZ was loaded into LDH with sodium cholate (SC), a surfactant with negative charge and, for comparison, without SC by the reconstruction method. Surprisingly, it was found that both resultant nanocomposites had similar CBZ encapsulation efficiency, around 75%, and the LDH-CBZ system without SC showed a better performance in relation to the release kinetics of CBZ in simulated body fluid (pH 7.4) and acetate buffer simulating the cellular cytoplasm (pH 4.8) than the system with SC. The CBZ dimensions were measured with Chem3D and, according to the basal spacing obtained from X-ray patterns, it can be arranged in the LDH-CBZ system as a monolayer with the long axis parallel to the LDH layers. Fourier transform infrared spectroscopy and solid state NMR measurements confirmed the presence of the drug, and thermogravimetric analyses showed an enhanced thermal stability for CBZ. These results have interesting implications since they increase the spectrum of LDH application as a controlled drug system to a large number of nonionic drugs, without the addition of other components.

Rifampicin loaded in alginate/chitosan nanoparticles as a promising pulmonary carrier against Staphylococcus aureus.

This study aims to explore the antimicrobial activity of rifampicin (RIF) and ascorbic acid (ASC) co-loaded into alginate (ALG)/chitosan (CS) nanoparticles (RIF/ASC NPs) and tested for their antibacterial activity against several strains of methicillin-sensitive Staphylococcus aureus (MSSA) and methicillin-resistant Staphylococcus aureus (MRSA). Also, the present research focused on exploring the possible antibacterial mechanism of action of these RIF/ASC NPs, which demonstrated a significant biocide activity against the S. aureus strains with minimum inhibitory concentrations (MIC) between 2- and 8-fold lower than those one exhibited with the free antibiotic RIF. The proposed antimicrobial mechanism of action of the RIF/ASC NPs seems to be the result of collaborative effects between NPs and the RIF/ASC antibiotic combination. Moreover, results indicated that the functionalized RIF/ASC NP surface played a crucial role on the processes of NP adhesion into the bacterial surface, the alterations on the cell membrane integrity, and the cell uptake of the RIF/ASC antibiotic into bacteria. Further, the in vivo lung deposition pattern of empty NPs labeled (NPs-FITC) with isothiocyanate fluorescein in rats was investigated post intratracheal instillation of NPs. In summary, findings from this work show that our novel designed engineered RIF/ASC co-loaded NPs could be a suitable system for antibiotic lung administration with promising perspectives for effective treatments of pulmonary intracellular infections for those known antibiotics that are losing effectiveness due to antimicrobial resistance problems. Graphical Abstract.