Poloxamer 407, also known by the trademark Pluronic
F127, is a water-soluble, non-ionic triblock copolymer that is made up of a hydrophobic residue of polyoxypropylene (POP) between the two ...hydrophilic units of polyoxyethylene (POE). Poloxamer 407-based hydrogels exhibit an interesting reversible thermal characteristic. That is, they are liquid at room temperature, but they assume a gel form when administered at body temperature, which makes them attractive candidates as pharmaceutical drug carriers. These systems have been widely investigated in the development of mucoadhesive formulations because they do not irritate the mucosal membranes. Based on these mucoadhesive properties, a simple administration into a specific compartment should maintain the required drug concentration in situ for a prolonged period of time, decreasing the necessary dosages and side effects. Their main limitations are their modest mechanical strength and, notwithstanding their bioadhesive properties, their tendency to succumb to rapid elimination in physiological media. Various technological approaches have been investigated in the attempt to modulate these properties. This review focuses on the application of poloxamer 407-based hydrogels for mucosal drug delivery with particular attention being paid to the latest published works.
Embedding of active substances in supramolecular systems has as the main goal to ensure the controlled release of the active ingredients. Whatever the final architecture or entrapment mechanism, ...modeling of release is challenging due to the moving boundary conditions and complex initial conditions. Despite huge diversity of formulations, diffusion phenomena are involved in practically all release processes. The approach in this paper starts, therefore, from mathematical methods for solving the diffusion equation in initial and boundary conditions, which are further connected with phenomenological conditions, simplified and idealized in order to lead to problems which can be analytically solved. Consequently, the release models are classified starting from the geometry of diffusion domain, initial conditions, and conditions on frontiers. Taking into account that practically all solutions of the models use the separation of variables method and integral transformation method, two specific applications of these methods are included. This paper suggests that "good modeling practice" of release kinetics consists essentially of identifying the most appropriate mathematical conditions corresponding to implied physicochemical phenomena. However, in most of the cases, models can be written but analytical solutions for these models cannot be obtained. Consequently, empiric models remain the first choice, and they receive an important place in the review.
Safety of Nanoparticles in Medicine Wolfram, Joy; Zhu, Motao; Yang, Yong ...
Current drug targets,
01/2015, Letnik:
16, Številka:
14
Journal Article
Recenzirano
Odprti dostop
Nanomedicine involves the use of nanoparticles for therapeutic and diagnostic purposes. During the past two decades, a growing number of nanomedicines have received regulatory approval and many more ...show promise for future clinical translation. In this context, it is important to evaluate the safety of nanoparticles in order to achieve biocompatibility and desired activity. However, it is unwarranted to make generalized statements regarding the safety of nanoparticles, since the field of nanomedicine comprises a multitude of different manufactured nanoparticles made from various materials. Indeed, several nanotherapeutics that are currently approved, such as Doxil and Abraxane, exhibit fewer side effects than their small molecule counterparts, while other nanoparticles (e.g. metallic and carbon-based particles) tend to display toxicity. However, the hazardous nature of certain nanomedicines could be exploited for the ablation of diseased tissue, if selective targeting can be achieved. This review discusses the mechanisms for molecular, cellular, organ, and immune system toxicity, which can be observed with a subset of nanoparticles. Strategies for improving the safety of nanoparticles by surface modification and pretreatment with immunomodulators are also discussed. Additionally, important considerations for nanoparticle safety assessment are reviewed. In regards to clinical application, stricter regulations for the approval of nanomedicines might not be required. Rather, safety evaluation assays should be adjusted to be more appropriate for engineered nanoparticles.
The success of many drugs in ophthalmic treatments is hindered by their physico-chemical properties and the limited precorneal retention time. Here, lyotropic liquid crystals are proposed as a new ...ophthalmic drug delivery system. Acyclovir was chosen as model drug for its solubility and its controlled release from cubic phase was achieved. We demonstrated the effortless application of lamellar phase on corneal surface and its ability to convert itself in cubic phase in situ. While the complex viscosity of lamellar phase was affected by temperature (5.1 ± 1.4 kPa·s at 25 °C and 0.12 ± 0.001 Pa·s at 35 °C, respectively), the cubic phase shown no changes in viscosity values and shear thinning behaviour at both temperatures and even in presence of the drug The degradation kinetic of drug-loaded cubic phase was slightly slower than the empty formulation, recording 27.92 ± 1.43% and 33.30 ± 3.11% of weight loss after 8 h. Ex vivo studies conducted on porcine eyeballs and isolated cornea confirmed the instantaneous transition to cubic phase, its ability to resist to gravity force, and forced dripping of simulated tear fluid. Histopathological investigation showed how treated cornea did not report changes in epithelial and stroma structures. In summary, lyotropic liquid crystals could represent an advantageous ophthalmic drug delivery system.
The controlled release of a compound entrapped in a biocompatible formulation is a sought-after goal in modern pharmaceutical technology. Zein is a hydrophobic protein which has several advantageous ...properties that make it suitable for use as a biocompatible and degradable material under physiological conditions. It is, therefore, proposed for different biomedical and pharmaceutical applications. In particular, due to its gelling properties, it can be used to form a polymeric network able to preserve biomolecules from harsh environments. The current study was designed to investigate the influence of different probes on the rheological properties of gels made up of zein, in order to characterize the systems as a function of the polymer concentration. Four model compounds characterized by different physico-chemical properties were entrapped in zein gels, and different behaviors (viscoelastic or pronounced solid-like characteristics) of the systems were observed. Zein-based gels showed various release profiles of the encapsulated compounds, suggesting that there are different interaction rates between the probes and the polymeric matrix.
In this study, we investigated the release kinetic of fluorescein from colloidal liquid crystals made from monoglyceride and different non-ionic surfactants. The crystals were physicochemically ...characterized and the release experiments were carried out under the sink conditions, while mathematical models were described as extrapolations from solutions of the diffusion equation, in different initial and boundary conditions imposed by pharmaceutical formulations. The diffusion equation was solved using Laplace and Fourier transformed functions for release kinetics from infinite reservoirs in a semi-infinite medium. Solutions represents a general square root law and can be applied for the release kinetic of fluorescein from lyotropic colloidal liquid crystals. Akaike, Schwartz, and Imbimbo criteria were used to establish the appropriate mathematical model and the hierarchy of the performances of different models applied to the release experiments. The Fisher statistic test was applied to obtain the significance of differences among mathematical models. Differences of mathematical criteria demonstrated that small or no significant statistic differences were carried out between the various applied models and colloidal formulations. Phenomenological models were preferred over the empirical and semi-empirical ones. The general square root model shows that the diffusion-controlled release of fluorescein is the mathematical models extrapolated for lyotropic colloidal liquid crystals.
Today there is a very great deal of interest among members of the global natural products community in investigating new plant constituents. Recent studies demonstrate that liquorice extracts are ...useful in the treatment of dermatitis, eczema, and psoriasis, with an efficacy comparable to that of corticosteroids. In this work, niosomes made up of surfactants (Tween 85 and Span 20) and cholesterol at various concentrations were prepared to investigate the potential application of niosomes for the delivery of ammonium glycyrrhizinate (AG), useful for the treatment of various inflammatory based diseases.
Vesicles were characterized evaluating dimensions, ζ potential, anisotropy, drug entrapment efficiency, stability, cytotoxicity evaluation and skin tolerability.
Release profiles of ammonium glycyrrhizinate/niosomes were evaluated in vitro using cellulose membranes. The best formulation was used to evaluate the in vitro/in vivo efficacy of the ammonium glycyrrhizinate/niosomes in murine and human models of inflammation.
The AG-loaded non-ionic surfactant vesicles showed no toxicity, good skin tolerability and were able to improve the drug anti-inflammatory activity in mice. Furthermore, an improvement of the anti-inflammatory activity of the niosome delivered drug was observed on chemically induced skin erythema in humans.
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Sclareol (labd‑14‑ene‑8,13‑diol), a phytochemical compound belonging to labdane-type diterpenes, has recently attracted noteworthy attention because of its peculiar pharmacological properties. The ...foremost obstacle to an efficacious application and use of this molecule is its unfavorable bioavailability due to its poor aqueous solubility. In this investigation sclareol was encapsulated within PLGA nanoparticles with the aim of favoring its administration in physiological media, increasing its anticancer activity and obtaining a stable colloidal formulation. These nanoparticles containing sclareol were characterized by a mean diameter of 100–150 nm, a narrow size distribution and a negative surface charge. The active compound was efficiently retained by the polymeric structure and did not induce any physical destabilization. The coating of the PLGA nanoparticles with hyaluronic acid (1.5 MDa) increased the antitumor efficacy of the encapsulated drug against human breast cancer cells expressing the hyaluronan receptors (MCF-7 and MDA-MB468) while a similar pharmacological effect was obtained on human colon carcinoma cells (CaCo-2). CLSM analysis demonstrated the intracellular localization of fluorescent nanosystems after 3 h incubation.
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•Sclareol (SCL) has been encapsulated within PLGA nanoparticles•The nanoencapsulation of SCL favors its administration in physiological media•The coating of SCL-nanoparticles with hyaluronan increases their anticancer activity on HA+ cells
Hydrogels have been extensively investigated to identify innovative formulations that can fulfill all the necessary purposes to improve local vaginal therapy through the mucosa. Herein, we propose in ...situ-forming lyotropic liquid crystals (LLCs) derived from a cheap and GRAS (generally recognized as safe) ingredient as an intravaginal delivery system. The system consists of a precursor solution loaded with sertaconazole nitrate as a model drug, which is able to easily swell in a stable three-dimensional structure by absorbing simulated vaginal fluid. Under polarized light microscopy the precursor solution and the formed phase of LLCs showed the typical textures belonging to anisotropic and an isotropic mesophases, respectively. A deep rheological investigation by Kinexus® Pro proved the stability and strength of the cubic phase, as well as its potential in mucoadhesion. In vitro degradation studies showed a slow matrix erosion, consistent with data obtained from lipophilic drug release studies in simulated vaginal fluid. Therefore, the suggested cubic phase based on lyotropic liquid crystals could represent a valid proposal as a vaginal drug delivery system due to its characteristics of resistance, adhesion and the possibility of providing a slow and controlled release of drugs directly at the administration site.
The encapsulation of miR-34a into chitosan/PLGA nanoparticles in order to obtain nanoplexes useful for the modulation of the biopharmaceutical features of the active compound was studied. The ...nanoplexes were obtained through nanoprecipitation and were characterized by a mean diameter of ~160 nm, a good size distribution and a positive surface charge. The structure of the nanoparticles allowed a high level of entrapment efficiency of the miR-34a and provided protection of the genetic material from the effects of RNase. A high degree of transfection efficiency of the nanoplexes and a significant in vitro antitumor effect against multiple myeloma cells was demonstrated. The therapeutic properties of the nanoplexes were evaluated in vivo against human multiple myeloma xenografts in NOD-SCID mice. The systemic injection of miR-34a mimic-loaded nanoparticles significantly inhibited tumor growth and translated into improved survival of the laboratory mice. RT-PCR analysis carried out on retrieved tumors demonstrated the presence of a high concentration of miR-34a mimics. The integrity of the nanoplexes remained intact and no organ toxicity was observed in treated animals.
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