scholarly journals Heat-stability study of various insulin types in tropical temperature conditions: New insights towards improving diabetes care

PLoS ONE ◽  
2021 ◽  
Vol 16 (2) ◽  
pp. e0245372
Author(s):  
Beatrice Kaufmann ◽  
Philippa Boulle ◽  
Flavien Berthou ◽  
Margot Fournier ◽  
David Beran ◽  
...  
Keyword(s):  
Diabetes Care ◽  
High Performance ◽  
3D Structure ◽  
Heat Stability ◽  
Stability Study ◽  
Critical Question ◽  
Humanitarian Emergency ◽  
Tropical Regions ◽  
Ambient Temperatures ◽  
Resource Poor

Strict storage recommendations for insulin are difficult to follow in hot tropical regions and even more challenging in conflict and humanitarian emergency settings, adding an extra burden to the management of people with diabetes. According to pharmacopeia unopened insulin vials must be stored in a refrigerator (2–8°C), while storage at ambient temperature (25–30°C) is usually permitted for the 4-week usage period during treatment. In the present work we address a critical question towards improving diabetes care in resource poor settings, namely whether insulin is stable and retains biological activity in tropical temperatures during a 4-week treatment period. To answer this question, temperature fluctuations were measured in Dagahaley refugee camp (Northern Kenya) using log tag recorders. Oscillating temperatures between 25 and 37°C were observed. Insulin heat stability was assessed under these specific temperatures which were precisely reproduced in the laboratory. Different commercialized formulations of insulin were quantified weekly by high performance liquid chromatography and the results showed perfect conformity to pharmacopeia guidelines, thus confirming stability over the assessment period (four weeks). Monitoring the 3D-structure of the tested insulin by circular dichroism confirmed that insulin monomer conformation did not undergo significant modifications. The measure of insulin efficiency on insulin receptor (IR) and Akt phosphorylation in hepatic cells indicated that insulin bioactivity of the samples stored at oscillating temperature during the usage period is identical to that of the samples maintained at 2–8°C. Taken together, these results indicate that insulin can be stored at such oscillating ambient temperatures for the usual four–week period of use. This enables the barrier of cold storage during use to be removed, thereby opening up the perspective for easier management of diabetes in humanitarian contexts and resource poor settings.

Development and Characterization Colchicine-Loaded PEGylated Gelatin Nanoparticles for Targeted Delivery to Tumor

2013 ◽  
Vol 6 (2) ◽  
pp. 2058-2063
Author(s):  
G D Chandrethiya ◽  
P K Shelat ◽  
M N Zaveri
Keyword(s):  
Drug Delivery ◽  
Targeted Delivery ◽  
High Performance ◽  
Entrapment Efficiency ◽  
Stability Study ◽  
Spherical Particles ◽  
Precipitation Method ◽  
Antitumoral Activity ◽  
Gelatin Nanoparticles

PEGylated gelatin nanoparticles loaded with colchicine were prepared by ethanol precipitation method. Poly-(ethylene glycol)-5000-monomethylether (MPEG 5000), a hydrophilic polymer, was used to pegylate gelatin.  Gluteraldehyde was used as cross-linking agent. To obtain a high quality product, major formulation parameters were optimized.  Spherical particles with mean particles of 193 nm were measured by a Malvern particle size analyzer. Entrapment efficiency was found to be 71.7 ± 1.4% and determined with reverse phase high performance liquid charomatography (RP-HPLC). The in vitro drug release study was performed by dialysis bag method for a period of 168 hours. Lyophilizaton study showed sucrose at lower concentrations proved the best cryoprotectant for this formulation.  Stability study revealed that lyophilized nanoparticles were equally effective (p < 0.05) after one year of storage at 2-8°C with ambient humidity. In vitro antitumoral activity was accessed using the MCF-7 cell line by MTT assay.  The IC50 value was found to be 0.034 μg/ml for the prepared formulation. The results indicate that PEGylated gelatin nanoparticles could be utilized as a potential drug delivery for targeted drug delivery of tumors.  

Azo (Hydrazone) pigments: general principles

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Robert Christie
Keyword(s):  
High Performance ◽  
Metal Salt ◽  
Low Cost ◽  
Cost Effective ◽  
Precipitation Process ◽  
Ambient Temperatures ◽  
Technical Performance ◽  
Chemical Structures ◽  
General Chemical ◽  
Physical Form

Abstract This paper presents an overview of the general chemical principles underlying the structures, synthesis and technical performance of azo pigments, the dominant chemical class of industrial organic pigments in the yellow, orange, and red shade areas, both numerically and in terms of tonnage manufactured. A description of the most significant historical features in this group of pigments is provided, starting from the discovery of the chemistry on which azo colorants are based by Griess in the mid-nineteenth century, through the commercial introduction of the most important classical azo pigments in the early twentieth century, including products known as the Hansa Yellows, β-naphthol reds, including metal salt pigments, and the diarylide yellows and oranges, to the development in the 1950s and 1960s of two classes of azo pigments that exhibit high performance, disazo condensation pigments and benzimidazolone-based azo pigments. A feature that complicates the description of the chemical structures of azo pigments is that they exist in the solid state as the ketohydrazone rather than the hydroxyazo form, in which they have been traditionally been illustrated. Numerous structural studies conducted over the years on an extensive range of azo pigments have demonstrated this feature. In this text, they are referred to throughout as azo (hydrazone) pigments. Since a common synthetic procedure is used in the manufacture of virtually all azo (hydrazone) pigments, this is discussed in some detail, including practical aspects. The procedure brings together two organic components as the fundamental starting materials, a diazo component and a coupling component. An important reason for the dominance of azo (hydrazone) pigments is that they are highly cost-effective. The syntheses generally involve low cost, commodity organic starting materials and are carried out in water as the reaction solvent, which offers obvious economic and environmental advantages. The versatility of the approach means that an immense number of products may be prepared, so that they have been adapted structurally to meet the requirements of many applications. On an industrial scale, the processes are straightforward, making use of simple, multi-purpose chemical plant. Azo pigments may be produced in virtually quantitative yields and the processes are carried out at or below ambient temperatures, thus presenting low energy requirements. Finally, provided that careful control of the reaction conditions is maintained, azo pigments may be prepared directly by an aqueous precipitation process that can optimise physical form, with control of particle size distribution, crystalline structure, and surface character. The applications of azo pigments are outlined, with more detail reserved for subsequent papers on individual products.

Perylene and perinone pigments

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Robert Christie ◽  
Adrian Abel
Keyword(s):  
High Performance ◽  
Heat Stability ◽  
High Heat ◽  
Structural Features ◽  
Fastness Properties ◽  
Tetracarboxylic Acid ◽  
Organic Pigments ◽  
Orange Color ◽  
Cis Isomer ◽  
Chemical Class

Abstract Perylenes and perinones are separate groups of pigments categorized within the carbonyl chemical class. The two pigment groups show similarities, for example, in their chemical structural features and, to an extent, in their technical and application properties as high-performance organic pigments. Perylenes constitute a series of firmly established high-performance pigments, offering red and violet colors, and also extending to black. Synthetically, they are derived from perylene-1,4,5,8-tetracarboxylic acid. The perylenes tend to be quite expensive pigments, but their high levels of fastness properties mean that they are suitable for highly demanding applications. In particular, they offer very high heat stability. Two perinone pigments are used commercially. In their synthesis from naphthalene-1,4,5,8-tetracarboxylic acid, they are formed as mixtures of the two isomers, which can be separated. The trans isomer, CI Pigment Orange 43, is a highly important commercial pigment, especially for plastics, while the cis isomer, CI Pigment Red 194, is bordeaux in color and is of much lesser importance. The perinone, CI Pigment Orange 43, provides a brilliant orange color and has very good fastness properties. Its commercial manufacture involves a challenging multistage procedure and consequently it is one of the most expensive organic pigments on the market.

Design and stability of pediatric oral formulation of imatinib

2021 ◽  
pp. 107815522199120
Author(s):  
Mélanie Hinterlang ◽  
Amandine Gendron ◽  
Thomas Fleury ◽  
André Rieutord ◽  
Anastasia Vrana ◽  
...  
Keyword(s):  
High Performance ◽  
Protein Tyrosine Kinase ◽  
Pediatric Patients ◽  
Kinase Inhibitor ◽  
Philadelphia Chromosome ◽  
Oral Solution ◽  
Stability Study ◽  
Uv Detector ◽  
Stability Parameters ◽  
Tablet Dosage

Background Imatinib is a protein-tyrosine kinase inhibitor which is currently only commercially available as a tablet dosage form in the strength of 100mg and 400mg. The elaboration of new oral liquid formulations is suitable in pediatrics and for patients who have difficulties to swallow, notably in the absence of commercial forms. This enables the adaptation of dosage and secure the administration. Objectives The formulation of an oral pediatric solution of imatinib at a concentration of 30 mg/mL and the evaluation of its stability for the treatment of pediatric patients with Philadelphia chromosome positive chronic myeloid leukemia. Methods The physicochemical stability parameters: appearance, pH, osmolality, and drug content of formulation were evaluated for 30 days when stored at 2–8°C. Concentration of solution was measured with a validated method using high performance liquid chromatography (HPLC) coupled with an absorbance UV detector. Equally, microbiological stability was performed. Results The remaining imatinib concentration was at least 95% of the initial concentration after 30 days stored in fridge temperature. No changes were observed regarding the physical properties of the formulation during the study period. Conclusions The stability study showed that the imatinib oral solution at a concentration of 30 mg/mL provides an alternative option at the commercial tablet dosage forms for pediatric patients and patients who have difficulties to swallow.

Physical characterisation and stability study of formulated Chromolaena odorata gel

2021 ◽  
Vol 18 ◽  
Author(s):  
Qurratul Ain Zakirah Mohd Zamram ◽  
Hannis Fadzillah Mohsin ◽  
Mashani Mohamad Mohamad ◽  
Nurul Aqmar Mohamad Nor Hazalin ◽  
Khuriah Abdul Hamid
Keyword(s):  
High Performance ◽  
Skin Diseases ◽  
Loss Modulus ◽  
Viscosity Index ◽  
Stability Study ◽  
Wound Management ◽  
Flavonoid Compound ◽  
Chromolaena Odorata ◽  
Skin Delivery ◽  
Materials Used

Aim: Formulating topical products for skin delivery has always been a challenge for pharmaceutical scientists to fulfil good formulation criteria. Despite the challenges, gel-based drug delivery offers some advantages such that it is non-invasive, painless, avoidance of the first-pass metabolism and has satisfactory patient compliance. Objectives: In this study, Chromolaena odorata gel and quercetin gel (bioactive flavonoid compound) were successfully formulated and compared with placebo and conventional wound aid gel. The chromatographic profilling was conducted to screen the presence of phytoconstituents. Subsequently, all formulated gels were subjected to physical characteristic and stability study. Methods: Reverse Phase High-Performance Liquid Chromatography (RP-HPLC) of C.odorata methanolic leaves extract shows a distinct compound separation at retention time 8.4min to 34.8 min at 254nm. All gels were characterised by evaluating their rheological properties including storage modulus, loss modulus and plastic viscosity. Besides, texture analysis was performed to measure the gels’ firmness, consistency, cohesiveness, and viscosity index. Results: From the observation, C. odorata gel demonstrated better spreadability as compared to the other gels, which acquired less work and favourable to be applied onto the skin. Moreover, C. odorata gel showed no changes in organoleptic properties and proven to be stable after 30 days of accelerated stability study at 40°C ± 2°C with relative humidity (RH) of 75%± 5%. Conclusion: C. odorata gel has shown to be stable, reflecting the combination of materials used in the formulation, which did not degrade throughout the study. This work suggests the potential of this gel as a vehicle to deliver the active ingredients of C. odorata to the skin, which can be further explored as a topical application in antimicrobial wound management or other skin diseases study.

High-performance liquid radiochromatography: Its application for stability study of [3H] stobadin

1989 ◽  
Vol 134 (2) ◽  
pp. 433-436 ◽  
Author(s):  
V. Ščasnár ◽  
M. Zemánek ◽  
L. Šoltés ◽  
M. Lukácsová
Keyword(s):  
High Performance ◽  
Stability Study

scholarly journals Tuning Dielectric Loss of SiO2@CNTs for Electromagnetic Wave Absorption

Nanomaterials ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 2636
Author(s):  
Fenghui Cao ◽  
Jia Xu ◽  
Xinci Zhang ◽  
Bei Li ◽  
Xiao Zhang ◽  
...  
Keyword(s):  
Electromagnetic Wave ◽  
High Performance ◽  
Low Cost ◽  
Impedance Matching ◽  
3D Structure ◽  
Carbon Matrix ◽  
Current Approach ◽  
Matrix Composites ◽  
Simple Method ◽  
Absorption Performance

We developed a simple method to fabricate SiO2-sphere-supported N-doped CNTs (NCNTs) for electromagnetic wave (EMW) absorption. EMW absorption was tuned by adsorption of the organic agent on the precursor of the catalysts. The experimental results show that the conductivity loss and polarization loss of the sample are improved. Meanwhile, the impedance matching characteristics can also be adjusted. When the matching thickness was only 1.5 mm, the optimal 3D structure shows excellent EMW absorption performance, which is better than most magnetic carbon matrix composites. Our current approach opens up an effective way to develop low-cost, high-performance EMW absorbers.

Three-Dimensional Graphite Filled Poly(Vinylidene Fluoride) Composites with Enhanced Strength and Thermal Conductivity

2020 ◽  
Vol 842 ◽  
pp. 63-68
Author(s):  
Xiao Zhang ◽  
Jian Zheng ◽  
Yong Qiang Du ◽  
Chun Ming Zhang
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Energetic Materials ◽  
High Performance ◽  
Vinylidene Fluoride ◽  
3D Structure ◽  
Three Dimensional ◽  
3D Network ◽  
Poly Vinylidene Fluoride ◽  
Polymer Bonded Explosives

Three-dimensional (3D) network structure has been recognized as an efficient approach to enhance the mechanical and thermal conductive properties of polymeric composites. However, it has not been applied in energetic materials. In this work, a fluoropolymer based composite with vertically oriented and interconnected 3D graphite network was fabricated for polymer bonded explosives (PBXs). Here, the graphite and graphene oxide platelets were mixed, and self-assembled via rapid freezing and using crystallized ice as the template. The 3D structure was finally obtained by freezing-dry, and infiltrating with polymer. With the increasing of filler fraction and cooling rate, the thermal conductivity of the polymer composite was significantly improved to 2.15 W m-1 K-1 by 919% than that of pure polymer. Moreover, the mechanical properties, such as tensile strength and elastic modulus, were enhanced by 117% and 563%, respectively, when the highly ordered structure was embedded in the polymer. We attribute the increased thermal and mechanical properties to this 3D network, which is beneficial to the effective heat conduction and force transfer. This study supports a desirable way to fabricate the strong and thermal conductive fluoropolymer composites used for the high-performance polymer bonded explosives (PBXs).

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