Rifabutin-Loaded Nanostructured Lipid Carriers as a Tool in Oral Anti-Mycobacterial Treatment of Crohn's Disease.

Oral anti-mycobacterial treatment of Crohn's disease (CD) is limited by the low aqueous solubility of drugs, along with the altered gut conditions of patients, making uncommon their clinical use. Hence, the aim of the present work is focused on the in vitro evaluation of rifabutin (RFB)-loaded Nanostructured lipid carriers (NLC), in order to solve limitations associated to this therapeutic approach. RFB-loaded NLC were prepared by hot homogenization and characterized in terms of size, polydispersity, surface charge, morphology, thermal stability, and drug payload and release. Permeability across Caco-2 cell monolayers and cytotoxicity and uptake in human macrophages was also determined. NLC obtained were nano-sized, monodisperse, negatively charged, and spheroidal-shaped, showing a suitable drug payload and thermal stability. Furthermore, the permeability profile, macrophage uptake and selective intracellular release of RFB-loaded NLC, guarantee an effective drug dose administration to cells. Outcomes suggest that rifabutin-loaded NLC constitute a promising strategy to improve oral anti-mycobacterial therapy in Crohn's disease.

Transfection of pulmonary cells by stable pDNA-polycationic hybrid nanostructured particles.

AIM: Cationically modified solid lipid nanoparticles (SLN) were investigated as plasmid DNA (pDNA) carriers and transfection agents for the pulmonary route. MATERIALS & METHODS: pDNA-loaded SLN were produced using glyceryl dibehenate or tristearate as matrix lipids and chitosan as surface charge modifier, and encapsulated by spray-drying in mannitol and trehalose microspheres. RESULTS: Nanoparticles of 200 nm, and zeta potential around +15 mV were produced. Electrophorectic analysis confirmed plasmid stability and integrity. The pDNA-loaded SLN were able to transfect the Calu-3 and A549 pulmonary cell lines, while showing low cytotoxicity. Microencapsulation of SLN yielded dry powders suitable for inhalation that protected pDNA from degradation. CONCLUSION: Microencapsulated SLN are a promising safe and effective carrier system for pulmonary gene delivery following pulmonary administration.

Microencapsulated Solid Lipid Nanoparticles as a Hybrid Platform for Pulmonary Antibiotic Delivery.

Solid lipid nanoparticles (SLN) containing rifabutin (RFB), with pulmonary administration purposes, were developed through a technique that avoids the use of organic solvents or sonication. To facilitate their pulmonary delivery, the RFB-loaded SLN were included in microspheres of appropriate size using suitable excipients (mannitol and trehalose) through a spray-drying technique. Confocal analysis microscopy showed that microspheres are spherical and that SLN are efficiently microencapsulated and homogeneously distributed throughout the microsphere matrices. The aerodynamic diameters observed an optimal distribution for reaching the alveolar region. The dry powder's performance during aerosolization and the in vitro drug deposition were tested using a twin-impinger approach, which confirmed that the microspheres can reach the deep lung. Isothermal titration calorimetry revealed that SLN have higher affinity for mannitol than for trehalose. Upon microsphere dissolution in aqueous media, SLN were readily recovered, maintaining their physicochemical properties. When these dry powders reach the deep lung, microspheres are expected to readily dissolve, delivering the SLN which, in turn, will release RFB. The in vivo biodistribution of microencapsulated RFB-SLN demonstrated that the antibiotic achieved the tested organs 15 and 30 min post pulmonary administration. Their antimycobacterial activity was also evaluated in a murine model of infection with a Mycobacterium tuberculosis strain H37Rv resulting in an enhancement of activity against M. tuberculosis infection compared to nontreated animals. These results suggest that RFB-SLN microencapsulation is a promising approach for the treatment of tuberculosis.

Microencapsulated SLN: An innovative strategy for pulmonary protein delivery.

Associating protein with nanoparticles is an interesting strategy to improve their bioavailability and biological activity. Solid lipid nanoparticles (SLN) have been sought as carriers for therapeutic proteins transport to the lung epithelium. Nevertheless, because of their low inertia, nanoparticles intended for pulmonary application usually escape from lung deposition. To overcome this problem, the production of spray-dried powders containing nanoparticles has been recently reported. Herein we developed new hybrid microencapsulated SLN for pulmonary administration, containing a model protein (papain, PAP). PAP was adsorbed onto glyceryl dibehenate and glyceryl tristearate SLN. Physical characterization using transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC) confirmed the interaction between PAP and SLN corroborating that the protein was efficiently adsorbed at SLN's surface. PAP adsorption onto SLN (PAP-SLN) slightly increased particle size, while decreasing the SLN negative surface charge. The adsorption process followed a Freundlich type of adsorption isotherm. Nanoformulations were then spray-dried, originating spherical microparticles with suitable aerodynamic characteristics. Full characterization of microparticles was performed using scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and isothermal titration calorimetry (ITC). PAP was released from dry powders in a higher extent when compared with non spray-dried SLN. Nevertheless, protein stability was kept throughout microsphere production, as assessed by SDS-PAGE.

Rifabutin-loaded solid lipid nanoparticles for inhaled antitubercular therapy: Physicochemical and in vitro studies.

Systemic administration of antitubercular drugs can be complicated by off-target toxicity to cells and tissues that are not infected by Mycobacterium tuberculosis . Delivery of antitubercular drugs via nanoparticles directly to the infected cells has the potential to maximize efficacy and minimize toxicity. The present work demonstrates the potential of solid lipid nanoparticles (SLN) as a delivery platform for rifabutin (RFB). Two different RFB-containing SLN formulations were produced using glyceryl dibehenate or glyceryl tristearate as lipid components. Full characterization was performed in terms of particle size, encapsulation and loading efficiency, morphology by transmission electron microscopy (TEM) and differential scanning calorimetry (DSC) studies. Physical stability was evaluated when formulations were stored at 5 ± 3°C and in the freeze-dried form. Formulations were stable throughout lyophilization without significant variations on physicochemical properties and RFB losses. The SLN showed to be able to endure harsh temperature conditions as demonstrated by dynamic light scattering (DLS). Release studies revealed that RFB was almost completely released from SLN. In vitro studies with THP1 cells differentiated in macrophages showing a nanoparticle uptake of 46 ± 3% and 26 ± 9% for glyceryl dibehenate and glyceryl tristearate SLN, respectively. Cell viability studies using relevant lung cell lines (A549 and Calu-3) revealed low cytotoxicity for the SLN, suggesting these could be new potential vehicles for pulmonary delivery of antitubercular drugs.