Factorial design approach to fabricate and optimize floating tablets based on combination of natural polymer and rice bran wax

Background The aim of the present research work was to fabricate a novel gastroretentive drug delivery system in the form of tablets using a combination of natural polymer and rice bran wax with an intention to control drug delivery and to enhance the gastric residence time of the model drug Famotidine in the gastrointestinal tract. Results The results of the preliminary trial batches prepared by using the hot melt granulation technique resulting in six different formulations showed good physicochemical characteristics and tablets conformed to the Pharmacopoeial specifications. Gastroretentive tablets containing natural polymer showed prolonged drug release comparable to Methocel. The optimized formulation (C3) using 32 factorial design showed FLT 27 ± 2.47 s, SI 92.68 ± 1.36% and % CDR 98.89 ± 0.39% at 12 h. The stability studies indicated the stability of the formulation during storage. Conclusions It was concluded that the release profile fitted best to zero-order equation with non-Fickian diffusion mechanism of drug release which demonstrates swelling-controlled drug release mechanism. Thus, the formulated tablets have the potential for improved release and gastroretentive properties. Graphical Abstract

Formulation of Nano/Micro-Carriers Loaded with an Enriched Extract of Coffee Silverskin: Physicochemical Properties, In Vitro Release Mechanism and In Silico Molecular Modeling

Designing strategies for an effective transformation of food waste into high-value products is a priority to address environmental sustainability concerns. Coffee silverskin is the major by-product of the coffee roasting industry, being rich in compounds with health benefits. Such composition gives it the potential to be transformed into high-value products. In this study, coffee silverskin extracts were enriched, regarding caffeine and chlorogenic acid contents, by adsorbent column chromatography. The compounds content increased 3.08- and 2.75-fold, respectively, compared to the original extract. The enriched fractions were loaded into nano-phytosomes or cholesterol-incorporated nano-phytosomes (first coating layers) to improve the physiochemical properties and permeation rate. These nano-lipid carriers were also subjected to a secondary coating with different natural polymers to improve protection and stability against degradation. In parallel, and for comparison, different natural polymers were also used as first coating layers. The produced particles were evaluated regarding product yield, encapsulation efficiency, loading capacity, particle size, surface charge, and in vitro release simulating gastrointestinal conditions. All samples exhibited anionic surface charge. FTIR and molecular docking confirmed interactions between the phytoconstituents and lipid bilayers. The best docking score was observed for 5-caffeoylquinic acid (chlorogenic acid) exhibiting a stronger hydrogen binding to the lipid bilayer. Among several kinetic models tested, the particle release mechanism fitted well with the First-order, Korsmeyer–Peppas, and Higuchi models. Moreover, most of the formulated particles followed the diffusion-Fick law and anomalous transport.

Nanoenviroments of the β-Subunit of L-Type Voltage-Gated Calcium Channels in Adult Cardiomyocytes

In cardiomyocytes, Ca2+ influx through L-type voltage-gated calcium channels (LTCCs) following membrane depolarization regulates crucial Ca2+-dependent processes including duration and amplitude of the action potentials and excitation-contraction coupling. LTCCs are heteromultimeric proteins composed of the Cavα1, Cavβ, Cavα2δ and Cavγ subunits. Here, using ascorbate peroxidase (APEX2)-mediated proximity labeling and quantitative proteomics, we identified 61 proteins in the nanoenvironments of Cavβ2 in cardiomyocytes. These proteins are involved in diverse cellular functions such as cellular trafficking, cardiac contraction, sarcomere organization and excitation-contraction coupling. Moreover, pull-down assays and co-immunoprecipitation analyses revealed that Cavβ2 interacts with the ryanodine receptor 2 (RyR2) in adult cardiomyocytes, probably coupling LTCCs and the RyR2 into a supramolecular complex at the dyads. This interaction is mediated by the Src-homology 3 domain of Cavβ2 and is necessary for an effective pacing frequency-dependent increase of the Ca2+-induced Ca2+ release mechanism in cardiomyocytes.

Heat shock protein (HSP) release mechanism under heat stress pressure in Goats: a review

Among the various climate variables, heat stress has been reported to be the most detrimental factor to the economy of the livestock industry. Heat stress is one of the most stressful events in the life of livestock with harmful consequences for animal health, productivity and product quality. Heat shock proteins (HSPs), also known as molecular chaperons, are prominent stress markers. Heat shock proteins consist of highly conserved protein expressed at the time of stress, and play an important role in adaptation to the environmental stress. This review discusses the scientific evidence regarding the effects of heat stress and role of HSP during heat stress on Goats.

Chitosan/Sodium Dodecyl Sulfate Complexes for Microencapsulation of Vitamin E and Its Release Profile—Understanding the Effect of Anionic Surfactant

Microencapsulation of bioactive substances is a common strategy for their protection and release rate control. The use of chitosan (Ch) is particularly promising due to its abundance, biocompatibility, and interaction with anionic surfactants to form complexes of different characteristics with relevance for use in microcapsule wall design. In this study, Ch/sodium dodecyl sulfate (SDS) microcapsules, without and with cross-linking agent (formaldehyde (FA) or glutaraldehyde (GA)), were obtained by the spray drying of vitamin E loaded oil-in-water emulsion. All of the microcapsules had good stability during the drying process. Depending on the composition, their product yield, moisture content, and encapsulation efficiency varied between 11–34%, 1.14–1.62%, and 94–126%, respectively. SEM and FTIR analysis results indicate that SDS as well as cross-linkers significantly affected the microcapsule wall properties. The profiles of in vitro vitamin E release from the investigated microcapsules fit with the Korsmeyer-Peppas model (r2 > 0.9). The chemical structure of the anionic surfactant was found to have a significant effect on the vitamin E release mechanism. Ch/SDS coacervates may build a microcapsule wall without toxic crosslinkers. This enabled the combined diffusion/swelling based release mechanism of the encapsulated lipophilic substance, which can be considered favorable for utilization in food and pharmaceutical products.

Effect of Polymers nature and Stirring Speeds on Physicochemical Properties and the Controlled Release of Allopurinol-loaded Microspheres

Allopurinol is an antigout drug therapy, commonly used in the treatment of chronic gout or hyperuricaemia associated with treatment of diuretic conditions. In the present study, new formulations based on Allopurinol, have been prepared with the microencapsulation by solvent evaporation process. Microspheres were prepared using pure Allopurinol and polymeric matrices (ethylcellulose EC, poly (ε-caprolactone) PCL, β-cyclodextrin CD and hydroxypropylmethylcellulose HPMC) at different compositions and stirring speeds to investigate the effect of these parameters on loading efficiency and drug release kinetics. The formulations produced were characterized by various methods : Fourier transforms infrared spectroscopy (FTIR), X-ray powder diffractometry, optical microscopy, surface morphology by scanning electron microscopy (SEM) and drug loading, as well as in vitro release studies in the simulated stomach tract. Depending on the stirring speed and the composition of the microparticles, the active ingredient loading is in a range from 10.46 ± 1.45 to 46.40 ± 0.5%. The microspheres are spherical and the mean Sauter diameter (d32) of the microparticles obtained is smaller and is in the range of 47.71 to 151.01 µm. Different release profiles were obtained and show that the release rate is strongly influenced by the characteristics of the microparticles ; namely, the stirring rates and the composition of the microparticles. The release mechanism was identified by modelling using Higuchi and Korsmeyer-Peppas models. Resumen. Alopurinol es una droga terapéutica para tratar la gota, y se utiliza en el tratamiento de gota crónica o hiperuricemia asociada con el tratamiento de condiciones diuréticas. En este estudio, nuevas formulaciones basadas en Alopurinol se prepararon mediante microencapsulación por el proceso de evaporación de disolvente. Microesferas se prepararon usando Alopurinol puro y diferentes matrices poliméricas (etil-celulosa EC, poli(-caprolactona) PCL, β-cyclodextrina CD e hidroxipropil-metil-celulose HPMC) en diferentes composiciones y velocidades de agitación, para investigar el efecto de estos parámetros en la eficiencia de carga y en la cinética de liberación del fármaco. Las formulaciones obtenidas fueron caracterizadas por diferentes técnicas : Espectroscopía infrarroja de transformadas de Fourier (FTIR), difractometría de rayos X de polvos, microscopía óptica, morfología de superficies mediante microscopía electrónica de barrido electrónico, y la eficiencia de carga del fármaco, así como estudios de liberación in vitro en tracto estomacal simulado. Dependiendo de la velocidad de agitación y la composición de las micropartículas, la carga del ingrediente activo se encuentra en el rango de 10.46 ± 1.45 a 46.40 ± 0.5%. Las microesferas son esféricas y el diámetro medio de Sauter (d32) de las micropartículas obtenidas es menor, y se encuentra en el rango de 47.71 a 151.01 µm. Se obtuvieron diferentes perfiles de liberación y se observa que la velocidad de liberación está influenciada principalmente por las características propias de la producción de las micropartículas ; en particualr, las velocidades de agitación y las composición de las micropartículas. El mecanismo de liberación se ajusta mejor a los modelos matemáticos de Higuchi and Korsmeyer-Peppas.

Structure and ion-release mechanism of PIB-4-type ATPases

Transition metals, such as zinc, are essential micronutrients in all organisms, but also highly toxic in excessive amounts. Heavy-metal transporting P-type (PIB) ATPases are crucial for homeostasis, conferring cellular detoxification and redistribution through transport of these ions across cellular membranes. No structural information is available for the PIB-4-ATPases, the subclass with the broadest cargo scope, and hence even their topology remains elusive. Here we present structures and complementary functional analyses of an archetypal PIB‑4‑ATPase, sCoaT from Sulfitobacter sp. NAS14-1. The data disclose the architecture, devoid of classical so-called heavy metal binding domains, and provides fundamentally new insights into the mechanism and diversity of heavy-metal transporters. We reveal several novel P-type ATPase features, including a dual role in heavy-metal release and as an internal counter ion of an invariant histidine. We also establish that the turn-over of PIB‑ATPases is potassium independent, contrasting to many other P-type ATPases. Combined with new inhibitory compounds, our results open up for efforts in e.g. drug discovery, since PIB-4-ATPases function as virulence factors in many pathogens.

ROSUVASTATIN CALCIUM NANOSPONGES IN THE FORMULATION OF EXTENDED RELEASE TABLETS

Cyclodextrin has been recognized as a linker molecule that can link with the various drug substances to produce a nano-porous structure called nanosponges (NS) and increase the dissolution rate of poorly soluble drug substances. This work aimed to load rosuvastatin calcium (RSC) with solubility enhancer’s β-cyclodextrin (β-CD) or polyvinyl alcohol (PVA). β-CD based RSC-NS were fabricated by the emulsion solvent diffusion technique; with solubilizer dichloromethane and different ratios of ethyl cellulose as a co-polymer. Characterization of the prepared nanosponges was done by various testing procedures that confirm its nanosize and particle size and drug release. RSC loading in NS was assessed by DSC, FTIR and SEM. Among all the formulations F5 has 78.23 % entrapment efficiency. 2-3 folds of increased solubility were obtained with RSC-NS. F1-F6 formulations released 76.35 % - 98.69 % of the drug at the end of 30 min. In the preparation of extended-release tablets, NS prepared from F5 formulation was used and the best tablet formulation was selected based on various evaluation tests. All the formulations except S3, S8 followed first-order release kinetics. S1 & S2 drug release mechanism is Higuchi while other formulations are Korsemeyer-Peppas, so the release mechanism for most of the formulations is erosion than diffusion.

Study on the Complexation and Release Mechanism of Methylphenidate Hydrochloride Ion Exchange Resin Complex

Since the advent of ion exchange resin, it has been widely used in many fields, including drug delivery systems. The drug binds to the resin through an exchange reaction to form a drug–resin complex, which can gradually release drugs through the exchange of physiological ions in the gastrointestinal tract, to realize functions such as taste masking and regulating release. In this study, the complexes of methylphenidate hydrochloride and Amberlite IRP69 were prepared and evaluated to explore the mechanism of complexation, influencing factors and release mechanism at a molecular level. Firstly, with the properties of the selected complexes, molecular dynamics simulation was innovatively used to find that the intermolecular interaction between drug molecules and ion exchange resin molecules is mainly caused by the stacking effect of π and salt bridges. Secondly, with the drug loading status as an indicator, the factors affecting the compounding process of the drug and resin were explored. Finally, the release mechanism of the drug–resin complex was studied by mathematical model fitting. In summary, a variety of methods were used to study the mechanism of complexation and release between drug and resin, providing a theoretical basis for promoting the marketing of ion−exchange resin−mediated oral preparations.