Development of Chitosan/Cyclodextrin Nanospheres for Levofloxacin Ocular Delivery.

Levofloxacin (LVF) is an antibacterial drug approved for the treatment of ocular infections. However, due to the low ocular bioavailability, high doses are needed, causing bacterial resistance. Polymeric nanospheres (NPs) loading antibiotic drugs represent the most promising approach to eradicate ocular infections and to treat pathogen resistance. In this study, we have developed chitosan NPs based on sulfobutyl-ether-ß-cyclodextrin (CH/SBE-ß-CD NPs) for ocular delivery of LVF. CH/SBE-ß-CD NPs loading LVF were characterized in terms of encapsulation parameters, morphology, and sizes, in comparison to NPs produced without the macrocycle. Nuclear magnetic resonance and UV-vis spectroscopy studies demonstrated that SBE-ß-CD is able to complex LVF and to influence encapsulation parameters of NPs, producing high encapsulation efficiency and LVF loading. The NPs were homogenous in size, with a hydrodynamic radius between 80 and 170 nm and positive zeta potential (ζ) values. This surface property could promote the interaction of NPs with the negatively charged ocular tissue, increasing their residence time and, consequently, LVF efficacy. In vitro, antibacterial activity against Gram-positive and Gram-negative bacteria showed a double higher activity of CH/SBE-ß-CD NPs loading LVF compared to the free drug, suggesting that chitosan NPs based on SBE-ß-CD could be a useful system for the treatment of ocular infections.

Physicochemical Characterization and Antioxidant Activity Evaluation of Idebenone/Hydroxypropyl-ß-Cyclodextrin Inclusion Complex †.

Idebenone (IDE) is an antioxidant drug active at the level of the central nervous system (CNS), whose poor water solubility limits its clinical application. An IDE/2-hydroxypropyl-ß-cyclodextrin (IDE/HP-ß-CD) inclusion complex was investigated by combining experimental methods and theoretical approaches. Furthermore, biological in vitro/ex vivo assays were performed. Phase solubility studies showed an AL type diagram, suggesting the presence of a 1:1 complex with high solubility. Scanning electron microscopy (SEM) allowed us to detect the morphological changes upon complexation. The intermolecular interactions stabilizing the inclusion complex were experimentally characterized by exploring the complementarity of Fourier-transform infrared spectroscopy in attenuated total reflectance geometry (FTIR-ATR) with mid-infrared light, Fourier-transform near-infrared (FT-NIR) spectroscopy, and Raman spectroscopy. From the temperature evolution of the O-H stretching band of the complex, the average enthalpy ΔHHB of the hydrogen bond scheme upon inclusion was obtained. Two-dimensional (2D) rotating frame Overhauser effect spectroscopy (ROESY) analysis and computational studies involving molecular modeling and molecular dynamics (MD) simulation demonstrated the inclusion of the quinone ring of IDE inside the CD ring. In vitro/ex vivo studies evidenced that complexation produces a protective effect of IDE against the H2O2-induced damage on human glioblastoma astrocytoma (U373) cells and increases IDE permeation through the excised bovine nasal mucosa.

Chitosan microspheres for intrapulmonary administration of moxifloxacin: interaction with biomembrane models and in vitro permeation studies.

Chitosan microspheres loaded moxifloxacin were prepared to obtain sustained release of the drug after intrapulmonary administration. The microspheres were produced by the spray-drying method using glutaraldehyde as the crosslinking agent. The particles were spherical with a smooth but distorted surface morphology and were of small size, ranging from 2.5 to 6.0microm, thus suitable for inhalation. In vitro release studies showed a significant burst effect for all crosslinked systems, followed by a prolonged moxifloxacin release, particularly in the presence of the highest glutaraldehyde concentration. Lipid vesicles made of dipalmitoylphosphatidylcholine (DPPC) were used as an in vitro biomembrane model to evaluate the influence of chitosan microspheres on the interaction of moxifloxacin with biological membranes. Differential scanning calorimetry was used as a simple and non-invasive technique of analysis. Moxifloxacin freely permeates through DPPC liposomes, interacting with the hydrophobic zone of the bilayers (lowering of the DeltaH value and loss of the cooperativity of the main transition peak). Uncrosslinked microspheres rapidly swelled and dissolved releasing free chitosan that was able to interact with liposomes (increase of DeltaH value), probably altering the biomembrane permeability to the drug. Crosslinked microspheres did not show this property. Pulmonary absorption of moxifloxacin-loaded chitosan microspheres was evaluated compared to the free drug. A monolayer of Calu-3 human bronchial epithelial cells mounted on Franz diffusion cells was used as an in vitro bronchial epithelium model. Microspheres retard the absorption of moxifloxacin and within 6h the cumulative amount of permeated drug was about 18%, 11% and 7% (w/w) for free moxifloxacin, moxifloxacin-loaded crosslinked and moxifloxacin-loaded uncrosslinked microspheres, respectively.

In vitro evaluation of quercetin-3-O-acyl esters as topical prodrugs.

Quercetin-3-O-acyl esters (I-VI) were synthesized and their usefulness as quercetin topical prodrugs was evaluated. Quercetin esters were assayed to determine their water stability and solubility, their susceptibility to undergoing enzymatic hydrolysis and their permeation through excised human skin. Quercetin ethyl (I) and hexyl (IV) esters proved poorly stable in aqueous media and they were not assayed further. Among the derivatives tested, quercetin propyl (II) and butyl (III) esters were more water-soluble than the parent drug. Esters II, III and V were readily hydrolyzed by human plasma and esters II and III penetrated excised human skin better than quercetin from aqueous saturated solutions. On the basis of the results obtained, esters II and III could be regarded as promising quercetin topical prodrugs.

Enhancement of drug affinity for cell membranes by conjugation with lipoamino acids. I. Synthesis and biological evaluation of lipophilic conjugates of tranylcypromine.

Conjugation with lipoamino acids (LAAs) increases the lipophilicity of drug molecules. Because of their amphipatic nature, they also provide the conjugated drugs a 'membrane-like character', capable to facilitate their interaction with and penetration through cell membranes and biological barriers. To study such a feature, our aim is to collect experimental and computational data using a novel series of lipophilic conjugates between a model drug (tranylcypromine (TCP)) and LAA residues containing a short, a medium or a long alkyl side chain (C-4 to C-16), to provide a wide range of lipophilicity. For comparison, a corresponding set of amides of TCP with alkanoic or fatty acids was prepared and characterized. Their in vitro monoamine oxidase inhibitory activity also tested.

Ultradeformable liposomes as multidrug carrier of resveratrol and 5-fluorouracil for their topical delivery.

Ultradeformable liposomes represent useful formulations able to increase the skin permeation of drug compounds. In this study, resveratrol- and 5-fluorouracil-loaded ultradeformable liposomes were investigated for the potential treatment of non-melanoma skin cancer. The in vitro anticancer activity of ultradeformable liposomes was tested on human skin cancer cells through viability-, cell cycle- and apoptosis-analysis. Furthermore, we tested the percutaneous permeation of ultradeformable liposomes using human stratum corneum and viable epidermis. The co-encapsulation of resveratrol and 5-fluorouracil (multi-drug carrier) in ultradeformable liposomes improved their anticancer activity on skin cancer cells as compared to both the free drug form and the single entrapped agents. These multi-drug ultradeformable liposomes arrest cell proliferation in G1/S, thus modifying the action of 5-fluorouracil and increasing the activity of resveratrol. This effect might depend on the ultradeformable liposomes, which may accumulate in deeper skin layers, thus generating a cutaneous depot from which resveratrol and 5-fluorouracil are gradually released. Resveratrol and 5-fluorouracil co-loaded ultradeformable liposomes could be a new nanomedicine for the treatment of squamous cell carcinoma, i.e., actinic keratosis, Bowen's disease, and keratoacanthoma.

Polyethylenimine and chitosan carriers for the delivery of RNA interference effectors.

INTRODUCTION: Manipulating gene activity represents a promising approach for the treatment of cancer and other diseases. The relatively recent discovery of RNA interference (RNAi) revolutionized therapeutic approaches in this field. RNA effectors can now be used to modify the activity of genes and theoretically control any biological process. AREA COVERED: However, the clinical application of RNAi has been limited by the inefficient delivery of RNA. Challenges associated with the in vivo use of RNAi mediators, include rapid degradation, uptake by the reticular endothelial system and inefficient cellular internalization. To date, various strategies have been developed in order to overcome these pitfalls. Among these approaches, non-viral delivery systems have gained increasing popularity, as they are generally considered safer than their viral counterparts. EXPERT OPINION: The use of cationic polymers, especially polyethylenimine and chitosan, for the in vivo delivery of doubled-stranded RNAs is discussed in this review.

Effects of external phase on D-cycloserine loaded W/O nanocapsules prepared by the interfacial polymerization method.

Water in oil (W/O) polybutylcyanoacrylate nanocapsules containing D-cycloserine (D-CS) for intranasal delivery were prepared by the interfacial polymerization method. Different oils, as external phase, for the preparation of the initial W/O miniemulsions were used and their effect on mean size and other physico-chemical properties were evaluated by photon correlation spectroscopy (PCS) and scanning electron microscopy (SEM) analysis. Two probes at different hydrophilicity were used to verify the internal aqueous nature of the core. Both miniemulsions and nanocapsules mean size and polydispersity index were influenced by the used external phase. Different entrapment efficiency were obtained for D-cycloserine-loaded nanocapsules correlated to the used oil [ranging from 39 to 51% encapsulation efficiency (E.E.)]. In vitro drug release showed an initial burst effect (ranging from 20 to 40%) followed by a slow release of D-CS for all preparations. This study demonstrated that many relevant physico-chemical and technological properties of polybutylcyanoacrylate nanocapsules prepared by interfacial polymerization of miniemulsions are significantly influenced by the external oil phase used.