Tailoring novel soft nano-vesicles 'Flexosomes' for enhanced transdermal drug delivery: Optimization, characterization and comprehensive ex vivo - in vivo evaluation.

The transdermal route is a convenient non-invasive way for drug delivery, however, the hydrophobic compact nature of stratum corneum (SC) forms an obstacle hindering the diffusion of drugs particularly hydrophilic ones. Hence, the purpose of this study was to develop novel soft nano-vesicles, entitled Flexosomes, amalgamating two penetration enhancers, ethanol and one edge activator (EA) from various types and different hydrophilic-lipophilic balances. The tailored vesicles were loaded with tropisetron hydrochloride (TRO), a potent highly-soluble anti-emetic, and compared with ethosomes. Aiming to preclude the formation of rigid non-deformable mixed micelles, all critical parameters; EA type, phosphatidylcholine-to-EA molar ratio, and cholesterol concentration, were optimized proving their influences on vesicle-to-micelle transitions. The prepared formulations were characterized in terms of visual inspection, particle size, polydispersity, zeta potential, turbidity measurements, entrapment efficiency, and vesicle morphology. The permeation mechanisms were assessed by differential scanning calorimetry on isolated SC. The modified vesicles, based on ethanol and either vitamin E or PEGylated castor oil derivatives exhibited the highest transdermal fluxes confirmed by a deeply tracking to dermis using confocal laser microscopy. Both vesicles demonstrated higher bioavailability relative to ethosomes, topical and oral aqueous solutions. The findings endorsed the effectiveness of tailored nano-vesicles in boosting TRO skin transport suggesting their applicability with various drug entities for enhanced transdermal delivery.

In vitro bioaccessibility of Al, Cu, Cd, and Pb following simulated gastro-intestinal digestion and total content of these metals in different Brazilian brands of yerba mate tea.

Yerba mate tea contains various biochemically active substances. However, it can contain toxic metals. Thus, this work reports the total concentrations of Cd, Cu, Pb and Al in the commercial products, as well as the concentrations in infusions prepared. The bioaccessibility of these metals in these infusions was determined for the first time by in vitro digestion. For Al, its bioaccessibility was estimated in the presence of other ingredients used in tea consumption. In addition, the concentrations of phenolic compounds in infusions were also determined. All metals studied were detected in the samples ranging from 76 ng g-1 (Cd) to 526 µg g-1 (Al). In general, Cd and Cu were the most bioaccessible metals, while Al was found in a relatively inert form. The addition of sugar and honey in infusions decreased the Al bioaccessibility. The relationship between the phenolic and the leaching of Al for the beverages was observed.

Preparation of drug-loaded small unilamellar liposomes and evaluation of their potential for the treatment of chronic respiratory diseases.

The aim of the present investigation was to evaluate the influence of liposome formulation on the ability of vesicles to penetrate a pathological mucus model obtained from COPD affected patients in order to assess the potential of such vesicles for the treatment of chronic respiratory diseases by inhalation. Therefore, Small Unilamellar Liposomes (PLAIN-LIPOSOMEs), Pluronic® F127-surface modified liposomes (PF-LIPOSOMEs) and PEG 2000PE-surface modified liposomes (PEG-LIPOSOMEs) were prepared using the micelle-to-vesicle transition (MVT) method and beclomethasone dipropionate (BDP) as model drug. The obtained liposomes showed diameters in the range of 40-65 nm, PDI values between 0.25 and 0.30 and surface electric charge essentially close to zero. The encapsulation efficiency was found to be dependent on the BDP/lipid ratio used and, furthermore, BDP-loaded liposomes were stable in size both at 37 °C and at 4 °C. All liposomes were not cytotoxic on H441 cell line as assessed by the MTT assay. The liposome uptake was evaluated through a cytofluorimetric assay that showed a non-significant reduction in the internalization of PEG-LIPOSOMEs as compared with PLAIN-LIPOSOMEs. The penetration studies of mucus from COPD patients showed that the PEG-LIPOSOMEs were the most mucus-penetrating vesicles after 27 h. In addition, PEG- and PF-LIPOSOMEs did not cause any effect on bronchoalveolar lavage fluid proteins after aerosol administration in the mouse. The results highlight that PEG-LIPOSOMEs show the most interesting features in terms of penetration through the pathologic sputum, uptake by airway epithelial cells and safety profile.

Calcium alginate microspheres containing metformin hydrochloride niosomes and chitosomes aimed for oral therapy of type 2 diabetes mellitus.

Metformin is an oral hypoglycemic agent used in the type 2 diabetes, whose poor bioavailability and short half-life make the development of effective extended-release formulations highly desirable. Different metformin-loaded chitosomal and niosomal formulations were developed and suitably characterized, but were unable to provide the desired sustained release. The entrapment of both kinds of colloidal dispersions in calcium alginate beads enabled to strongly reduce the amount of drug released at gastric level (from 18 up to a maximum of 30%), and to obtain a sustained release in simulated intestinal fluid, which was properly tuned by varying the percentage of calcium alginate in the beads. In vivo studies on rats revealed a significant improvement of metformin hypoglycemic effect when orally administered as chitosomal and even more as niosomal dispersion entrapped in alginate beads, not only with respect to the drug as such, but also to the alginate beads loaded with the plain drug. The more intense and sustained therapeutic effect with time provided by the drug-in niosomes-in alginate bead formulation could be very profitable for maintaining tight blood glucose levels over prolonged period of time after oral administration, allowing a reduction of its dose and related collateral effects, and improving patient compliance.

Correlating gastric emptying of amphotericin B and paracetamol solid lipid nanoparticles with changes in particle surface chemistry.

Oral delivery of pharmaceuticals requires that they retain their physical and chemical attributes during transit within the gastrointestinal (GI) tract, for the manifestation of desired therapeutic profiles. Solid lipid nanoparticles (SLNs) are used as carriers to improve the absorption of hydrophobic drugs. In this study, we examine the stability of amphotericin B (AmB) and paracetamol (PAR) SLNs in simulated GI fluids during gastric emptying. On contact with the simulated fluids, the particles increased in size due to ingress of the dissolution media into the particles. Simulated gastric emptying revealed that the formulations had mean sizes <350nm and neutral surface charges, both of which are optimal for intestinal absorption of SLNs. There was ingress of the fluids into the SLNs, followed by diffusion of the dissolved drug, whose rate depended on the solubility of the loaded-drug in the particular medium. Time-of-flight secondary ion mass spectrometry analyses indicated that drug loading followed the core-shell model and that the AmB SLNs have a more drug-enriched core than the PAR SLNs do. The AmB SLNs are therefore a very suitable carrier of AmB for oral delivery. The stability of the SLNs in the simulated GI media indicates their suitability for oral delivery.

Comparison of liposomal and NLC (nanostructured lipid carrier) formulations for improving the transdermal delivery of oxaprozin: Effect of cyclodextrin complexation.

The combined strategy of drug-cyclodextrin (CD) complexation and complex loading into nanocarriers (deformable liposomes or nanostructured lipid carriers (NLC)), was exploited to develop effective topical formulations for oxaprozin transdermal administration. Oxaprozin was loaded as ternary complex with randomly-methylated-ßCD and arginine, selected as the best system in improving drug solubility. The colloidal dispersions, characterized for particle size, zeta-potential and entrapment efficiency, were investigated for drug permeation properties in comparison with a plain drug aqueous suspension, a ternary complex aqueous solution and a plain drug liposomal or NLC dispersion. Experiments with artificial membranes showed that the joined use of CD and both liposomes or NLC enabled a marked increase of the drug permeability (16 and 8 times, respectively) and was significantly more effective (P<0.05) than the drug as ternary complex (3.2 times increase), and the corresponding liposomal or NLC dispersion of plain drug (5.6 and 4.3 times increase, respectively). Experiments with excised human skin confirmed the significantly (P<0.05) better performance of deformable liposomes than NLC in promoting drug permeation; moreover, they evidenced a more marked permeability increase compared to the plain drug (24 and 12 fold, respectively), attributed to a possible enhancer effect of the nanocarriers components and/or of the randomly-methylated-ßCD.

Aspirin prevents bone loss with little mechanical improvement in high-fat-fed ovariectomized rats.

Obesity and osteoporosis are often concurrently happened in the menopausal women. Obesity in menopausal women is not only related to a high risk of cardiovascular disease, but also results in a detrimental effect on bone health. This study aimed to investigate the effects of aspirin, a popular anti-thrombosis drug, on bone quantity and quality in the high-fat-fed animal model. Adult female rats were subjected to either sham operations or ovariectomized operations. The ovariectomized rats were orally administered with deionized water or standardized high fat emulsion with or without aspirin. All rats were injected with calcein before killed for the purpose of double in vivo labeling. Biochemistry, histomorphometry, micro-computed tomography analysis, mechanical test, and component analysis were performed after 12 weeks. In vitro cell culture was also performed to observe the effect of aspirin in osteogenesis. We found that high fat remarkably impaired bone formation and bone biomechanics. Aspirin treatment significantly prevented bone loss by increasing bone formation. In vitro studies also validated the enhancement of osteogenic differentiation. However, aspirin presented no significant improvement in bone mechanical properties. Component analysis shown aspirin could significantly increase the content of mineral, but had limited effect on the content of collagen. In conclusion, aspirin is beneficial for the prevention of bone loss; meanwhile, it may cause an imbalance in the components of bone which may weaken the mechanical properties. The current study provided further evidence that aspirin might not be powerful for the prevention of fracture in osteoporotic patients.

Optimization of elastic transfersomes formulations for transdermal delivery of pentoxifylline.

Pentoxifylline (PTX) is a xanthine derivative indicated in treatment of intermittent claudication and chronic occlusive arterial diseases. It has low oral bioavailability and short half-life; thus, it was considered as a good candidate drug for the transdermal transfersomes formulation. In the present study, an attempt has been made for development, in-vitro and in-vivo evaluation of transdermal transfersomes using sodium cholate (SC) and non-ionic surfactants as edge activators. The optimal formulation, F4(Gcholate), exhibited drug entrapment efficiency of 74.9±1.6%, vesicles elasticity of 145±0.6 (mgs(-1)cm(-2)), zeta potential of -34.9±2.2mV, average vesicle diameter of 0.69±0.049µm with PDI of 0.11±0.037 and permeation flux of 56.28±0.19µgcm(-2)h(-1). It attained a prolonged drug release where 79.1±2.1% of PTX released after 10h of the run. The drug release kinetic obeys Higuchi model (R(2)=0.997) with Fickian diffusion mechanism. Moreover, the formula enhanced drug permeation through the excised rat's skin predominantly via the carrier-mediated mechanism by 9.1 folds in comparison with the control. Results of the in vivo pharmacokinetics study in male volunteers showed that F4(Gcholate) transfersomes formulation increased PTX absorption and prolonged its half-life comparing to the commercial oral SR tablets. Hence, the elastic transfersomes formulation of PTX possesses admirable potential to avoid drug metabolism, improve PTX bioavailability and sustain its release.

Lipoamino acid-based micelles as promising delivery vehicles for monomeric amphotericin B.

Lipoamino acid-based micelles have been developed as delivery vehicles for the hydrophobic drug amphotericin B (AmB). The micellar solubilisation of AmB by a gemini lipoamino acid (LAA) derived from cysteine and its equimolar mixtures with the bile salts sodium cholate (NaC) and sodium deoxycholate (NaDC), as well as the aggregation sate of the drug in the micellar systems, was studied under biomimetic conditions (phosphate buffered-saline, pH 7.4) using UV-vis spectroscopy. Pure surfactant systems and equimolar mixtures were characterized by tensiometry and important parameters were determined, such as critical micelle concentration (CMC), surface tension at the CMC (γCMC), maximum surface excess concentration (Γmax), and minimum area occupied per molecule at the water/air interface (Amin). Rheological behaviour from viscosity measurements at different shear rates was also addressed. Solubilisation capacity was quantified in terms of molar solubilisation ratio (χ), micelle-water partition coefficient (KM) and Gibbs energy of solubilisation (ΔGs°). Formulations of AmB in micellar media were compared in terms of drug loading, encapsulation efficiency, aggregation state of AmB and in vitro antifungal activity against Candida albicans. The LAA-containing micellar systems solubilise AmB in its monomeric and less toxic form and exhibit in vitro antifungal activity comparable to that of the commercial formulation Fungizone.