1,720,968 research outputs found
Melatonin-loaded lecithin/chitosan nanoparticles: Physicochemical characterisation and permeability through Caco-2 cell monolayers
No full textIn this study, the potential of lecithin/chitosan nanoparticles (NPs) as a mucoadhesive colloidal nanosystem for transmucosal delivery of melatonin was investigated. The size, zeta potential and melatonin loading of the lecithin/chitosan NPs were investigated as a function of lecithin type (Lipoid S45, S75 and S100) and chitosan content in the preparation. The NPs were characterised by mean diameter and zeta potential ranging between 121.6 and 347.5 nm, and 7.5 and 32.7 mV, respectively, and increasing with lecithin-negative charge and chitosan content in the preparation. Melatonin loadings were up to 7.1%. All NPs were characterised by prolonged release profiles with an initial burst (approximately 25%), followed by a slowrelease phase. Approximately 60–70% of melatoninwas released in 4 h. The permeability of melatonin was investigated using Caco-2 cells as an in vitro model of the epithelial barrier
Spray-dried chitosan/ethylcellulose microspheres for nasal drug delivery: swelling study and evaluation of in vitro drug release properties
No full textThe aim of this study was to develop spray-dried chitosan-based microspheres, suitable for nasal
delivery of loratadine, and to evaluate their potential of modifying loratadine release. The microspheres
were composed with ethylcellulose (EC) and chitosan (CM) in two different weight ratios, 1:2 and 1:3.
One-phase systems (dispersions) and two-phase systems (emulsions and suspensions) were subjected
to spray-drying, resulting in conventional and composed microspheres, respectively. The microspheres
were evaluated with respect to the yield, particle size, encapsulation efficiency, physical state of the
drug in the polymer matrix, swelling properties and in vitro drug release profile. It was shown that
particle size, swelling ability and loratadine release from spray-dried microspheres were significantly
affected by the polymeric composition and feed concentration in spray-drying process. Emulsifying
method to produce composed EC/CM microspheres resulted in improved loratadine entrapment
and moderate swelling, when compared to conventional chitosan microspheres. It seems like better
formation of EC cores and chitosan coating were obtained when higher feed concentration and
ultrasonic homogenization were employed in the preparation of emulsion systems and when EC to
CM weight ratio was 1:
Development and bioadhesive properties of chitosan-ethylcellulose microspheres for nasal delivery
No full textLoratadine-loaded microspheres were prepared by spray-drying of dispersions, emulsions and suspensions differing in polymeric
composition and solvents used. Conventional microspheres were obtained by spray-drying of dispersions composed of
chitosan (CM) as only polymer, while composed microspheres were obtained by spray-drying of two-phase systems composed
of chitosan and ethylcellulose (EC). Microspheres differed in EC/CM weight ratio (0:1, 1:2 and 1:3) and in loratadine/polymers
weight ratio (1:6 and 1:8).
The entrapment efficiencies were between 67.9 and 86.1%; less loratadine was entrapped as polymer/drug ratio decreased.
In comparison to one-phase systems composed of CM as only polymer, spray-drying of two-phase systems composed of both,
CM and EC resulted in improved loratadine entrapment (80.1–86.1%). All microspheres were positively charged, indicating the
presence of chitosan at the surface, regardless of the drug content and the type of spray-dried system. The highest zeta-potential
was measured for loratadine-free conventional microspheres, consisting of chitosan only (32.7±1.3 mV). Tensile studies showed
that both, EC/CM ratio and the type of spray-dried system influenced the bioadhesive properties of the microspheres in a way
that the microspheres with higher chitosan content were more bioadhesive and microspheres prepared from suspensions were
more bioadhesive than those prepared from emulsions, regardless of the same polymeric composition. The results suggested that
the spray-drying method is useful to produce bioadhesive loratadine-loaded microspheres.
© 2004 Elsevier B.V. All rights reserved
Preparation and evaluation of a melt pelletised paracetamol/stearic acid sustained release delivery system.
No full textThe potential of a sustained release formulation for paracetamol produced by melt pelletisation was investigated. The
chosen formulation was based on the combination of stearic acid as a melting binder and anhydrous lactose as a filler. After
determination of the size distribution, the pellet characterisation included scanning electron microscopy (SEM), X-ray
photoelectron spectroscopy (XPS), specific surface area and true density determination. Hence, the in vitro release from
every single size fraction (2000, 1250, 800, 630, ,630 mm) was evaluated and the release mechanism was analysed with the
help of an appropriate mathematical model. The results of drug content and superficial atomic composition were found to be
constant in all pellets size fractions, attesting the ability of melt pelletisation in a high shear mixer to form a product with
homogeneous composition. The mathematical model is built on the hypotheses that drug diffusion and solid drug dissolution
in the release environment are the key phenomena affecting drug release kinetics. Smaller classes apart (particles are not
perfectly spherical), the comparison between model best fitting and experimental data indicated the reasonability of these
hypotheses. Moreover, model reliability is proved by its ability of predicting drug release from a known mixture of the above
mentioned particles classes
Preparation and in vitro/in vivo characterisation of a melt pelletised paracetamol/stearic acid sustained release delivery system
No full textThe potential of a sustained release formulation for paracetamol produced by melt pelletisation was investigated.
After the production of the pellets, based on the combination of stearic acid as a melting binder and anhydrous lactose as a
filler, the 3000–2000 μm size fraction was selected in the light of the promising in vitro dissolution results for further characterisations,
including scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), specific surface area and
true density determination. Hence the release mechanism was analysed with the help of an appropriate mathematical model.
The mathematical model was built on the hypotheses that drug diffusion and solid drug dissolution in the release environment
are the key phenomena affecting drug release kinetics. Bioavailability of the developed formulation was evaluated in an in vivo
study in eight subject
Self-emulsifying pellets prepared by wet granulation in high-shear mixer: influence of formulation variables and preliminary study on the in vitro absorption
No full textA method of producing self-emulsifying pellets by wet granulation of powder mixture composed of microcrystalline cellulose, lactose and nimesulide as model drug with a mixture containing mono- and di-glycerides, polisorbate 80 and water, in a 10-l high shear mixer has been investigated. The effects of the formulation variables on pellets characteristics were evaluated by mixtures experimental design and by a polynomial model, in order to describe the phenomenon, to verify eventual interactions among components of the mixture and to investigate the feasibility of scaling-up. After determination of size distribution, the pellets were characterised by scanning electron microscopy, dissolution and disintegration tests, and by in vitro absorption test Such an approach, applied to the development of a self-emulsifying system for nimesulide as poorly water-soluble model drug, resulted in different formulations with improved drug solubility and permeability characteristics. The data demonstrate that pellets composed of oil to surfactant ratio of 1:4 (w/w) presented improvement in performance in permeation experiments
Spray-dried carbamazepine-loaded chitosan and HPMC microspheres: preparation and characterisation.
No full textLysozyme-containing chitosan-coated arginate microspheres for oral immunisation
No full textA set of ten different chitosan-coated alginate microspheres (MS1-10), containing hen-egg white lysozyme (LZ) as immunostimulant, was developed for the oral delivery of antigens. MS10, the formulation chosen for in vivo studies, charged with heat-inactivated Vibrio anguillarum (VA), presents mean dry and swollen diameter, zetapotential value, LZ and VA encapsulation efficiency of 2.7 ± 1.1 pm, 3.2 ± 1.2 pm, 2.1 ± 0.6 mV, 45.5% and 65.0%, respectively. The immunomodulating properties of the system were preliminarily tested on CBA mice model. A 6 consecutive-day oral immunization with microencapsulated VA induces a significant humoral immune response. The presence of LZ in the system contributes to increase the immune response against co-encapsulated VA vs. VA loaded MSs (IgM and IgG) or non encapsulated VA (IgM). The microencapsulation seems to improve the VA uptake by Peyer's patches (PP) vs. free particulate. These results provide useful insights into the suitability of this system for oral immunization with microencapsulated antigens
Use of low-field NMR and rheology to evaluate the microstructure and stability of a poly(D,L-lactide-co-glycolide)-based W/O emulsion to be processed by spray drying
Full text linkDrug-loaded emulsions for spray drying should be optimised for their rheological behaviour and stability under operating conditions, as this is essential for achieving the desired physicochemical properties of the final dry product. Our aim was therefore to investigate the structure and stability of a water-in-oil (W/O) emulsion containing vancomycin hydrochloride as the active ingredient in the aqueous phase, poly(D,L-lactide-co-glycolide) as the structural polymer in the dichloromethane-based organic phase, and various stabilisers using low-field nuclear magnetic resonance (LF NMR) and rheological characterisation. Four emulsions were tested, namely-one without stabiliser, one with Poloxamer® 407, one with chitosan and SpanTM 80 and one with chitosan only. The theoretical interpretation of the rheological data allowed the determination of the velocity and the shear rate/stress profiles inside the feed path of the W/O emulsion, aspects that are critical for the industrial scale-up of the emulsion drying process. In addition, LF NMR demonstrated that shaking was sufficient to restore the original emulsion structure and that the droplet size of all emulsions was in the range of 1–10 μm, although the emulsion with chitosan had the narrowest droplet size distribution and the higher zero shear viscosity, which accounts for the increased long-term stability due to impeded droplets movement
- …
