Controlled release chitosan microspheres of mirtazapine: In vitro and in vivo evaluation

ROS-sensitive Crocin-loaded chitosan microspheres for lung targeting and attenuation of radiation-induced lung injury

Radiation-induced lung injury (RILI) is one of the major complications in patients exposed to accidental radiation and radiotherapy for thoracic malignancies. However, there is no reliable radioprotector for effective clinical treatment of RILI so far. Herein, a novel Crocin-loaded chitosan microsphere is developed for lung targeting and attenuation of RILI. The chitosan microspheres are modified with 4-carboxyphenylboronic acid and loaded with the natural antioxidant Crocin-I to give the drug-loaded microspheres (~10 μm). The microspheres possess good biocompatibility in vivo and in vitro. In a mouse model, they exhibit effective passive targeting performance and a long retention time in the lung after intravenous administration. Furthermore, they improve the radioprotective effect of Crocin-I for the treatment of RILI by reducing the level of inflammatory cytokines in bronchoalveolar lavage fluid and by regulating oxidative stress in lung tissues. The targeted agents significantly improved the bioavailability and radioprotection of Crocin-I by the outstanding passive targeting effect. This work may provide a promising strategy for efficient radioprotection on RILI using passive lung targeting microspheres.

Water-soluble chitosan-derived sustainable materials: towards filaments, aerogels, microspheres, and plastics

Bioinspired materials have aroused great interest as their inherent biocompatible and structural characteristics have given rise to sustainable applications. In this work, we have reported the phase and morphology transformation of chitosan from crystalline nanofibrils into amorphous sheets for fabricating sustainable materials. Acetylation-induced aqueous dissolution of native chitosan nanofibrils affords water-soluble chitosan as a biopolymeric liquid. Water-soluble chitosan macromolecules self-aggregate into amorphous sheets on solidification, presenting an interesting way to inspire new structures of chitosan assemblies. Through control over gelation, lyophilization, and self-assembled confinement of water-soluble chitosan, we have fabricated novel chitosan materials including filaments, aerogels, microspheres, and plastics that are promising for sustainable use.

Lipid-polymer hybrid nanoparticles: Development & statistical optimization of norfloxacin for topical drug delivery system

Poly lactic acid is a biodegradable, biocompatible, and non-toxic polymer, widely used in many pharmaceutical preparations such as controlled release formulations, parenteral preparations, surgical treatment applications, and tissue engineering. In this study, we prepared lipid-polymer hybrid nanoparticles for topical and site targeting delivery of Norfloxacin by emulsification solvent evaporation method (ESE). The design of experiment (DOE) was done by using software to optimize the result, and then a surface plot was generated to compare with the practical results. The surface morphology, particle size, zeta potential and composition of the lipid-polymer hybrid nanoparticles were characterized by SEM, TEM, AFM, and FTIR. The thermal behavior of the lipid-polymer hybrid nanoparticles was characterized by DSC and TGA. The prepared lipid-polymer hybrid nanoparticles of Norfloxacin exhibited an average particle size from 178.6 ± 3.7 nm to 220.8 ± 2.3 nm, and showed very narrow distribution with polydispersity index ranging from 0.206 ± 0.36 to 0.383 ± 0.66. The surface charge on the lipid-polymer hybrid nanoparticles were confirmed by zeta potential, showed the value from +23.4 ± 1.5 mV to +41.5 ± 3.4 mV. An Antimicrobial study was done against Staphylococcus aureus and Pseudomonas aeruginosa, and the lipid-polymer hybrid nanoparticles showed potential activity against these two. Lipid-polymer hybrid nanoparticles of Norfloxacin showed the %cumulative drug release of 89.72% in 24 h. A stability study of the optimized formulation showed the suitable condition for the storage of lipid-polymer hybrid nanoparticles was at 4 ± 2 °C/60 ± 5% RH. These results illustrated high potential of lipid-polymer hybrid nanoparticles Norfloxacin for usage as a topical antibiotic drug carriers.

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Efficient topical drug delivery systems of norfloxacin have been synthesized.

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Norfloxacin loaded to the core of lipid- polymer hybrid nanoparticles were prepared.

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The formulations were optimized by factorial design and characterization techniques.

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A unique formulation of norfloxacin that offer prolonged and control delivery.

Fabrication and characterization of microspheres encapsulating astrocytes for neural regeneration

Astrocytes play a critical role in supporting the normal physiological function of neurons. Recent studies have revealed that astrocyte transplantation can promote axonal regeneration and functional recovery after spinal cord injury. Biomaterial can be designed as a growth-permissive substrate and serve as a carrier for astrocyte transplantation into injured spinal cord. In this study, we developed a method to generate collagen microspheres encapsulating astrocytes by injecting a mixture of collagen and astrocytes into a cell culture medium with a syringe controlled by a syringe pump. The collagen microspheres were crosslinked with poly(ethylene glycol) ether tetrasuccinimidyl glutarate (4S-StarPEG) to reduce the degradation rate. The viability of cells in the crosslinked microspheres was higher than 90%. Astrocytes were transfected with plasmids encoding nerve growth factor (NGF)-ires-enhanced green fluorescent protein (EGFP) genes by electroporation and encapsulated in crosslinked microspheres. The level of NGF released into the cell culture medium was higher than that remaining in the microspheres or astrocytes. When microspheres encapsulating astrocytes transfected with plasmids encoding NGF-ires-EGFP genes were added into the cultured rat dorsal root ganglion, the axonal growth was significantly enhanced. This study shows that the microspheres can be potentially used as a carrier of astrocytes to promote nerve regeneration in injured neural tissue.

Long-term controlled release of PLGA microparticles containing antidepressant mirtazapine

The aim of the study was to prepare PLGA microparticles for prolonged release of mirtazapine by o/w solvent evaporation method and to evaluate effects of PVA concentration and organic solvent choice on microparticles characteristics (encapsulation efficiency, drug loading, burst effect, microparticle morphology). Also in vitro drug release tests were performed and the results were correlated with kinetic model equations to approximate drug release mechanism. It was found that dichloromethane provided microparticles with better qualities (encapsulation efficiency 64.2%, yield 79.7%). Interaction between organic solvent effect and effect of PVA concentration was revealed. The prepared samples released the drug for 5 days with kinetics very close to that of zero order (R(2 )= 0.9549 - 0.9816). According to the correlations, the drug was probably released by a combination of diffusion and surface erosion, enhanced by polymer swelling and chain relaxation.

Collagen microsphere serving as a cell carrier supports oligodendrocyte progenitor cell growth and differentiation for neurite myelination in vitro

Introduction

Microspheres fabricated from natural materials serve as a promising biodegradable and biocompatible carrier in a small volume for efficient cell delivery to the lesion of the injured neural tissue to generate biological functions. As the major component of extracellular matrix and due to its natural abundance within the body, collagen may be fabricated into microspheres and improve the ability of pre-seeded cells on the microspheres to encounter the hostile micro-environment in the lesion.

Methods

In this study, collagen microspheres were fabricated using the water-in-oil emulsion technique and cross-linked with 1-ethyl-3-(3-dimethylaminopropryl) carbodiimide. Oligodendrocyte progenitor cells isolated from postnatal day P1 to 2 rats were cultured and differentiated on the microspheres. The microspheres carrying the oligodendrocyte progenitor cells were co-cultured with dorsal root ganglions from 15-day-old rat embryos. The myelination formation was studied for the co-culture of oligodendrocyte progenitor cells and dorsal root ganglions.

Results

We showed that the viability of oligodendrocyte progenitor cells, B104 cells and PC12 cells grown on microspheres was not significantly different with those in cell culture plates. Oligodendrocyte progenitor cells differentiated into oligodendrocytes on collagen microspheres. The oligodendrocytes grown on microspheres extended processes that wrapped the axons of dorsal root ganglion neurons and the formation of myelin sheath was observed in the co-culture.

Conclusions

This study demonstrates the feasibility of collagen microspheres in further applications for the delivery of neural progenitor cells for neural regeneration.

Pharmacokinetics of mirtazapine and its main metabolites after single intravenous and oral administrations in rats at two dose rates

BACKGROUND

Mirtazapine (MRZ) is a human antidepressant drug metabolized to 8-OH mirtazapine (8-OH) and dimethylmirtazapine (DMR) metabolites. Recently, this drug has been proposed as a potential analgesic for use in a multidrug analgesic regime in the context of veterinary medicine. The aim of this study was to assess the pharmacokinetics of MRZ and its metabolites DMR and 8-OH in rats.

FINDINGS

Eighteen fasted, healthy male rats were randomly divided into 3 groups (n = 6). Animals in these groups were respectively administered MRZ at 2 and 10 mg/kg orally and 2 mg/kg intravenously. Plasma MRZ and metabolite concentrations were evaluated by HPLC-FL detection method. After intravenous administration, MRZ was detected in all subjects, while DMR was only detected in three. 8-OH was not detected. After oral administration, MRZ was detected in 3 out of 6 rats treated with 2 mg/kg, it was detected in 6 out of 6 animals in the 10 mg/kg group. DMR was only detectable in the latter group, while 8-OH was not detected in either group. The oral bioavailability was about 7% in both groups.

CONCLUSIONS

The plasma concentration of the MRZ metabolite 8-OH was undetectable, and the oral bioavailability of the parental drug was very low.

In vitro analysis of nanoparticulate hydroxyapatite/chitosan composites as potential drug delivery platforms for the sustained release of antibiotics in the treatment of osteomyelitis

Nanoparticulate composites of hydroxyapatite (HAp) and chitosan were synthesized by ultrasound-assisted sequential precipitation and characterized for their microstructure at the atomic scale, surface charge, drug release properties, and combined antibacterial and osteogenic response. Crystallinity of HAp nanoparticles was reduced because of the interference of the surface layers of chitosan with the dissolution/reprecipitation-mediated recrystallization mechanism that conditions the transition from the as-precipitated amorphous calcium phosphate phase to the most thermodynamically stable one--HAp. Embedment of 5-10 nm sized, narrowly dispersed HAp nanoparticles within the polymeric matrix mitigated the burst release of the small molecule model drug, fluorescein, bound to HAp by physisorption, and promoted sustained-release kinetics throughout the 3 weeks of release time. The addition of chitosan to the particulate drug carrier formulation, however, reduced the antibacterial efficacy against S aureus. Excellent cell spreading and proliferation of osteoblastic MC3T3-E1 cells evidenced on microscopic conglomerates of HAp nanoparticles in vitro also markedly diminished on HAp/chitosan composites. Mitochondrial dehydrogenase activity exhibited normal values only for HAp/chitosan particle concentrations of up to 2 mg/cm(2) and significantly dropped, by about 50%, at higher particle concentrations (4 and 8 mg/cm(2)). The gene expression of osteocalcin, a mineralization inductor, and the transcription factor Runx2 was downregulated in cells incubated in the presence of 3 mg/cm(2) HAp/chitosan composite particles, whereas the expression of osteopontin, a potent mineralization inhibitor, was upregulated, further demonstrating the partially unfavorable osteoblastic cell response to the given particles. The peak in the expression of osteogenic markers paralleling the osteoblastic differentiation was also delayed most for the cell population incubated with HAp/chitosan particles. Overall, the positive effect of chitosan coating on the drug elution profile of HAp nanoparticles as carriers for the controlled delivery of antibiotics in the treatment of osteomyelitis was compensated for by the lower bacteriostatic efficiency and the comparatively unviable cell response to the composite material, especially at higher dosages.

Osmotically controlled pulsatile release capsule of montelukast sodium for chronotherapy: statistical optimization, in vitro and in vivo evaluation

The purpose of present study was to design, optimize and evaluate osmotically controlled pulsatile release capsule (PRC) of montelukast sodium (MKS) for the prevention of episodic attack of asthma in early morning and associated allergic rhinitis. Assembly of the capsular systems consisted of push, active and plug tablet arranged from bottom to top in hard gelatin capsule. The capsule system was coated with a semi-permeable membrane of cellulose acetate and drilled towards plug side in cap. A three-factor, three-level central composite design (CCD) with α = 1 was introduced to execute the experiments and quadratic polynomial model was generated to predict and assess the independent variables with respect to the dependent variables. The composition of optimal formulation was determined as weight of push tablet 138 mg (coded value: +0.59), plug tablet 60 mg (coded value: +0.49) and coating weight gain of 8.4 mg (coded value: -0.82). The results showed that the optimal formulation of PRCs had lag time of 4.5 h, release at 6 and 12 h are 61.95% and 96.29%, respectively. The X-ray radiographic imaging study was carried out to monitor the in vivo behavior of developed barium sulfate-loaded PRCs in rabbits under fasting conditions. In vivo pharmacokinetic study revealed Tmax of 2 h for marketed tablets; however 7 h for PRCs with initial lag time of 4 h. Thus designed capsular system may be helpful for patients with episodic attack of asthma in early morning and associated allergic rhinitis.

Genipin-cross-linked fucose-chitosan/heparin nanoparticles for the eradication of Helicobacter pylori

Helicobacter pylori is a significant human pathogen that recognizes specific carbohydrate receptors, such as the fucose receptor, and produces the vacuolating cytotoxin, which induces inflammatory responses and modulates the cell-cell junction integrity of the gastric epithelium. The clinical applicability of topical antimicrobial agents was needed to complete the eradication of H. pylori in the infected fundal area. In the present study, we combined fucose-conjugated chitosan and genipin-cross-linking technologies in preparing multifunctional genipin-cross-linked fucose-chitosan/heparin nanoparticles to encapsulate amoxicillin of targeting and directly make contact with the region of microorganism on the gastric epithelium. The results show that the nanoparticles effectively reduced drug release at gastric acids and then released amoxicillin in an H. pylori survival situation to inhibit H. pylori growth and reduce disruption of the cell-cell junction protein in areas of H. pylori infection. Furthermore, with amoxicillin-loaded nanoparticles, a more complete H. pylori clearance effect was observed, and H. pylori-associated gastric inflammation in an infected animal model was effectively reduced.