Impact of various solid carriers and spray drying on pre/post compression properties of solid SNEDDS loaded with glimepiride: in vitro-ex vivo evaluation and cytotoxicity assessment

Development of self-nanoemulsifying drug delivery systems (SNEDDS) of glimepiride is reported with the aim to achieve its oral delivery. Lauroglycol FCC, Tween-80, and ethanol were used as oil, surfactant, and co-surfactant, respectively as independent variables. The optimized composition of SNEDDS formulation (F1) was 10% v/v Lauroglycol FCC, 45% v/v Tween 80, 45% v/v ethanol, and 0.005% w/v glimepiride. Further, the optimized liquid SNEDDS were solidified through spray drying using various hydrophilic and hydrophobic carriers. Among the various carriers, Aerosil 200 was found to provide desirable flow, compression, dissolution, and diffusion. Both, liquid and solid-SNEDDS have shown release of more than 90% within 10?min. Results of permeation studies performed on Caco-2 cell showed that optimized SNEDDS exhibited 1.54 times higher drug permeation amount and 0.57 times lower drug excretion amount than that of market tablets at 4?hours (p?p?>?.05, i.e. 0.74). The formulation was found stable with temperature variation and freeze thaw cycles in terms of droplet size, zeta potential, drug precipitation and phase separation. Crystalline glimepiride was observed in amorphous state in solid SNEDDS when characterized through DSC, PXRD, and FT-IR studies. The study revealed successful formulation of SNEDDS for glimepiride.     

一种亲水反应型聚氨酯在高寒草原生态修复中的应用研究

高寒草原退化以及沙化现象对当地的生态系统造成严重破坏。在多种生态修复措施中,以材料措施为技术核心的生态修复措施受到广泛关注。本工作选用一种亲水反应型聚氨酯(OH-1A)作为主要材料,对其进行相关性能研究。结果表明:在15 ℃条件下,OH-1A可分散于水中,发生固化反应形成弹性凝胶体,且固化速率与浓度成正比;当OH-1A浓度达到3%时,可在300 s内渗透50 mm,并发生固化反应,形成柔性固结层;固结层表面静态接触角可达143°,优异的表面疏水性能有助于减缓植物生长所需水分的蒸发。在沙化严重的高寒草原,以OH-1A为基础的材料措施,可为植物的生根发芽提供有利的保障环境,防止草种或幼苗受到恶劣环境的影响,即建设“植物栖息”环境。因此,本工作提出的材料措施生态修复技术在高寒草原的植被恢复研究和应用中具有较高的潜在价值。     

Effect of cathodic hydrogen-charging current density on the hydrogen diffusivity in nanostructured bainitic steels

ABSTRACT

The effect of cathodic hydrogen-charging current on the effective hydrogen diffusivity in nanostructured bainitic steels produced at transformation temperatures 200°C (BS200) and 350°C (BS350) was investigated and compared to that of mild steel. The effective hydrogen diffusivity at 10?mA?cm^?2 was the lowest for BS200, followed by BS350 and mild steel, due to the finer microstructure and higher dislocation density in the bainitic ferrite of BS200. Increase in the hydrogen-charging current density, i.e. 20 and 30?mA?cm^?2, increased the effective hydrogen diffusivity of mild steel by 37 and 135%, and BS350 by 49 and 150%, respectively. For BS200, the increase was not significant (2%) at 20?mA?cm^?2, but increased by 34% at 30?mA?cm^?2.

This paper is part of a thematic issue on Hydrogen in Metallic Alloys     

Development of a Soluplus budesonide freeze-dried powder for nasal drug delivery

Objective: The aim of this work was to develop an amorphous solid dispersions/solutions (ASD) of a poorly soluble drug, budesonide (BUD) with a novel polymer Soluplus^® (BASF, Germany) using a freeze-drying technique, in order to improve dissolution and absorption through the nasal route.

Significance: The small volume of fluid present in the nasal cavity limits the absorption of a poorly soluble drug. Budesonide is a corticosteroid, practically insoluble and normally administered as a suspension-based nasal spray.

Methods: The formulation was prepared through freeze-drying of polymer-drug solution. The formulation was assessed for its physicochemical (specific surface area, calorimetric analysis and X-ray powder diffraction), release properties and aerodynamic properties as well as transport in vitro using RPMI 2650 nasal cells, in order to elucidate the efficacy of the Soluplus–BUD formulation.

Results: The freeze-dried Soluplus–BUD formulation (LYO) showed a porous structure with a specific surface area of 1.4334?±?0.0178 m²/g. The calorimetric analysis confirmed an interaction between BUD and Soluplus and X-ray powder diffraction the amorphous status of the drug. The freeze-dried formulation (LYO) showed faster release compared to both water-based suspension and dry powder commercial products. Furthermore, a LYO formulation, bulked with calcium carbonate (LYO-Ca), showed suitable aerodynamic characteristics for nasal drug delivery. The permeation across RPMI 2650 nasal cell model was higher compared to a commercial water-based BUD suspension.

Conclusions: Soluplus has been shown to be a promising polymer for the formulation of BUD amorphous solid suspension/solution. This opens up opportunities to develop new formulations of poorly soluble drug for nasal delivery.     

A Predictive Instrument for Sensitive and Expedited Measurement of Ultra-Barrier Permeation

The reliable operation of flexible display devices poses a significant engineering challenge regarding the metrology of high barriers against water vapor. No reliable results have been reported in the range of 10^–6 g∙(m²∙d)⁻¹, and there is no standard ultra-barrier for calibration. To detect trace amount of water vapor permeation through an ultra-barrier with extremely high sensitivity and a greatly reduced test period, a predictive instrument was developed by integrating permeation models into high-sensitivity mass spectrometry measurement based on dynamic accumulation, detection, and evacuation of the permeant. Detection reliability was ensured by means of calibration using a standard polymer sample. After calibration, the lower detection limit for water vapor permeation is in the range of 10^–7 g∙(m²∙d)⁻¹, which satisfies the ultra-barrier requirement. Predictive permeation models were developed and evaluated using experimental data so that the steady-state permeation rate can be forecasted from non-steady-state results, thus enabling effective measurement of ultra-barrier permeation within a significantly shorter test period.     

Microstructural and Interfacial Designs of Oxygen‐Permeable Membranes for Oxygen Separation and Reaction–Separation Coupling

Mixed ionic–electronic conducting oxygen‐permeable membranes can rapidly separate oxygen from air with 100% selectivity and low energy consumption. Combining reaction and separation in an oxygen‐permeable membrane reactor significantly simplifies the technological scheme and reduces the process energy consumption. Recently, materials design and mechanism investigations have provided insight into the microstructural and interfacial effects. The microstructures of the membrane surfaces and bulk are closely related to the interfacial oxygen exchange kinetics and bulk diffusion kinetics. Therefore, the permeability and stability of oxygen‐permeable membranes with a single‐phase structure and a dual‐phase structure can be adjusted through their microstructural and interfacial designs. Here, recent advances in the development of oxygen permeation models that provide a deep understanding of the microstructural and interfacial effects, and strategies to simultaneously improve the permeability and stability through microstructural and interfacial design are discussed in detail. Then, based on the developed high‐performance membranes, highly effective membrane reactors for process intensification and new technology developments are highlighted. The new membrane reactors will trigger innovations in natural gas conversion, ammonia synthesis, and hydrogen‐related clean energy technologies. Future opportunities and challenges in the development of oxygen‐permeable membranes for oxygen separation and reaction–separation coupling are also explored.     

Properties of rubbery polymers for the recovery of hydrogen sulfide from gasification gases

Polydimethyl siloxane (PDMS) and two polyether‐polyamide copolymers (trade name Pebax) were evaluated for their ability to transport and separate gasification gases. Specifically, the permeabilities of hydrogen, carbon monoxide, carbon dioxide, and hydrogen sulfide were evaluated at temperatures up to 200°C. The permeabilities of all gases were approximately ten times faster through the PDMS than the Pebax materials. The permeabilities through all materials at all temperatures evaluated were H₂S > CO₂ > H₂ > CO. As the temperature increased, the permeabilities of all gases increased through the Pebax. Conversely, for PDMS, hydrogen and carbon monoxide permeabilites increased with temperature while those of H₂S and CO₂ decreased. The H₂S/H₂ selectivities ranges from 1.2 (PDMS at 200°C) to 10.3 (Pebax 2533 at 35°C). The activation energies for permeation of these polymer/penetrant pairs are reported. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2436–2444, 2002     

Dissolution of softwood kraft pulps by direct derivatization in lithium chloride/N,N‐dimethylacetamide

A method for the characterization of the molar mass distributions (MMDs) of softwood kraft pulps dissolved in 0.5% lithium chloride (LiCl)/N,N‐dimethylacetamide (DMAc) by size exclusion chromatography is presented. The method is based on derivatization with ethyl isocyanate and the dissolution of samples in 8% LiCl/DMAc. In this study, the derivatization of hardwood kraft pulps did not influence the MMD. In the case of softwood pulps, however, the derivatization decreased the proportion of the high‐molecular‐mass material and increased the proportion of the low‐molecular‐mass material, which resulted in a distribution similar to the MMD of a hardwood kraft pulp. The results suggest that associations between hemicellulose and cellulose in the softwood kraft pulp were ruptured during derivatization. This led to a more correct estimation of the MMD of derivatized softwood kraft pulps than obtained by the dissolution of nonderivatized samples. This new method offers several advantages over derivatization with phenyl isocyanate: a precipitation step is not necessary, it is possible to follow the lignin distribution in the samples, and the method allows very high levels of dissolution of softwood kraft pulps up to a κ number of around 50. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 424–431, 2004     

Morphology and barrier mechanism of biaxially oriented poly(ethylene terephthalate)/poly(ethylene 2,6‐naphthalate) blends

To improve the barrier properties of poly(ethylene terephthalate) (PET), PET/poly(ethylene 2,6‐naphthalate) (PEN) blends with different concentrations of PEN were prepared and were then processed into biaxially oriented PET/PEN films. The air permeability of bioriented films of pure PET, pure PEN, and PET/PEN blends were tested by the differential pressure method. The morphology of the blends was studied by scanning electron microscopy (SEM) observation of the impact fracture surfaces of extruded PET/PEN samples, and the morphology of the films was also investigated by SEM. The results of the study indicated that PEN could effectively improve the barrier properties of PET, and the barrier properties of the PET/PEN blends improved with increasing PEN concentration. When the PEN concentration was equal to or less than 30%, as in this study, the PET/PEN blends were phase‐separated; that is, PET formed the continuous phase, whereas PEN formed a dispersed phase of particles, and the interface was firmly integrated because of transesterification. After the PET/PEN blends were bioriented, the PET matrix contained a PEN microstructure consisting of parallel and extended, separate layers. This multilayer microstructure was characterized by microcontinuity, which resulted in improved barrier properties because air permeation was delayed as the air had to detour around the PEN layer structure. At a constant PEN concentration, the more extended the PEN layers were, the better the barrier properties were of the PET/PEN blends. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1309–1316, 2006