Matrix Erosion Research Articles

Characterization of Taro (Colocasia esculenta) stolon polysaccharide and evaluation of its potential as a tablet binder in the formulation of matrix tablet

This investigation focuses on the extraction, characterization, and evaluation of taro (Colocasia esculenta) stolon polysaccharide (TSP) as a tablet binding agent, which is obtained from edible taro stolon. TSP was subjected to phytochemical screening and characterized by FTIR, DSC, TGA, DTA, XRD, particle size, polydispersity index, zeta potential, rheological behavior, and SEM. The tablets prepared with varying concentrations of TSP (2.5 %, 5 %, 7.5 %, and 10 % w/w) and diclofenac sodium (DS) were evaluated and compared with the same concentrations of gum acacia and PVP K-30. The presence of carbohydrates was confirmed by Molisch's test. The FTIR spectra established the compatibility of the drug with excipients. The SEM images revealed asymmetric and elongated particles of TSP powder. The hydration kinetics study showed matrix hydration and water penetration velocity within the range of 0.602–0.753 g/g and 0.112–0.189 cm/g.h, respectively. The tablets showed drug release of >75 % at 45 min. The release-exponent value above 0.89 indicated a super case II drug transport combining matrix erosion and diffusion. Optimum tablet hardness and very low friability, even at 2.5 % binder concentration, suggested the potential application of the novel TSP as a tablet binder in the formulation of the tablets.

Synthesis and characterization of oleic acid-stabilized cobalt ferrite @MCM-41/nanocomposites for pH-responsive drug delivery

This study presents composite nanoparticles combining cobalt ferrites-oleic acid (CF-OA) and mesoporous silica (MCM-41) for drug delivery. Temperature-dependent analyses at 25 and 42 °C reveal distinct alterations in particle size and distribution, emphasizing the role of oleate complexes in stabilizing the nanocomposites. Power of Laws calculations (n = 0.58, m = 0.44) assessed diffusion and matrix erosion effects, highlighting the pH-responsive behavior. Results showed CF-OA@MCM-41with nanometric scale and predominantly spherical morphology influenced by temperature variations. Nitrogen BET analysis revealed a surface area of 542.1 m2g−1 and a pore volume of 1.1 cm3g−1. Drug release studies demonstrated controlled doxorubicin (DOX) release from CF-OA@MCM-41. In vivo studies showed significant tumor growth suppression (liver cancer): average tumor volume in D-C@M group was 167.8 mm3 after 21 days, compared to 1953.8 mm3, 1203.6 mm3, and 269 mm3 for PBS, CF-OA@MCM-41, and DOX alone respectively. In vitro, a 3 µg mL−1 concentration showed no significant 293 T cell viability change and increased HEP G2 cell viability. Significant HEP G2 cell viability inhibition occurred at 1 and 2 µg mL−1 CF-OA@MCM-41 carrying DOX, with p-values < 0.01 and < 0.001. CF-OA@MCM-41 nanoparticles exhibit promising potential for targeted cancer therapy due to their pH sensitivity and controlled drug release capabilities.

Simultaneous vehiculation of curcumin and riboflavin in bigels produced through WPI cold-set gelation

The influence of curcumin (model hydrophobic compound) and riboflavin (model hydrophilic compound) on the structure and physicochemical properties of bigels produced with cold-set whey protein isolates (WPI) was assessed. The hydrogel phase was produced with WPI (11% w/v) while for the oleogel phase, sunflower oil and glycerol monostearate (GM) (10% w/v) were used. Curcumin (0.03 mg/mL) was added to the oil phase and riboflavin (0.5 mg/mL) to the water phase. Bigels were produced by hot emulsification (18.000 min−1, 2 min, 55 °C) of different hydrogel:oleogel ratios (90:10, 50:50 and 10:90). NaCl (200 mM) was added to the aqueous phase prior the emulsification. Bigels were evaluated through microscopy, XRD, FTIR, viscoelastic, texture, release kinetics and in vitro digestion analyses. XRD and FTIR showed that the addition of compounds led to some possible structural differences. Microscopy images showed an increase of the oil droplets size proportionally to the amount of oil present, and a conversion of the structure from oil in water (O/W) to water in oil (W/O). The structural differences led to different mechanical behavior. For the bigels with the isolated compounds an improvement in the gel network was observed, making it more structured, according to the phase that is being added. Regarding controlled release, higher values for the 90:10 formulation were observed for both compounds due to the matrix erosion. For bioaccessibility, curcumin presented similar values for 90:10 and 10:90 bigels, and riboflavin showed a growing bioaccessibility, with lower values for bigel 90:10.

The Impacts of Micro‐Porosity and Mineralogical Texture on Fractured Rock Alteration

AbstractGeochemically driven alterations of fractures in multi‐mineral media can create altered layers (ALs) at the fracture‐matrix interface. Spatial variations in the AL significantly influence mass transfer across the interface, and the hydraulic and mechanical properties of the fractured medium. A real‐rock based microfluidic experiment reported spatial variations in AL thickness despite the initially smooth fracture surface, suggesting potential effects of matrix heterogeneity on AL development. However, the respective contribution of structural and mineralogical characteristics is still poorly understood. Using the microfluidic experimental data and a micro‐continuum reactive transport model, we systematically evaluated how micro‐porosity and initial mineral texture impact AL development and thus the overall reactive transport behaviors. Our simulation results confirmed that the extent of AL spatial variations, mainly controlled by mineralogical texture, influences the evolution of reaction and permeability in different ways. Accounting for spatial heterogeneity in mineral distribution produces “channeling” structures in ALs and lower overall reaction (by up to 35.6%), but larger permeability increase (by up to 9.8%). The characteristic length of the reactive mineral cluster was observed to dominate the internal texture of ALs. Whereas the presence of micro‐porosity can enhance mineral accessibility via improving connectivity for flow and transport, and lead to both higher bulk reaction, that is, thicker ALs, and permeability enhancement. Considerations of surface roughness with characteristic length on the same order of magnitude as mineral texture did not change the overall development of AL, which further highlights the importance of accounting for rock matrix properties in predicting long‐term evolution of fractured media. The resulting spatial variations of ALs and their impacts on bulk properties, however, are expected to be further complicated by the coupling of chemical and mechanical processes, and may trigger matrix disaggregation, erosion and other mechanisms of fractured media alteration.

Mechanistic Investigation of Enzyme Triggered Release from a Xyloglucan Matrix Tablet for Controlled Colonic Drug Delivery

The objective of this study was to investigate the mechanisms underlying drug release from a controlled colonic release (CCR) tablet formulation based on a xyloglucan polysaccharide matrix and identify the factors that control the rate of release for the purpose of fundamentally substantiating the concept and demonstrating its robustness for colonic drug delivery. Previous work demonstrated in vitro limited release of 5-aminosalicylic acid (5-ASA) and caffeine from these tablets in small intestinal environment and significant acceleration of release by xyloglucanase, an enzyme of the colonic microbiome. Targeted colonic drug delivery was verified in an animal study in vivo. In the present work, interaction of the xyloglucan matrix tablets with aqueous dissolution media containing xyloglucanase was found to lead to the spontaneous formation of a hydrated highly viscous gummy layer at the surface of the matrix which had a reduced drug content compared to the underlying regions and persisted with a nearly constant thickness that was inversely correlated to the enzyme concentration throughout the duration of the release process. Enzymatic hydrolysis of xyloglucan was determined to take place at the surface of the matrix leading to matrix erosion and a relation for the rate of enzymatic reaction as a function of bulk enzyme concentration and the concentration of dissolved xyloglucan in the gummy layer was derived. A mathematical model was developed encompassing aqueous medium ingress, matrix metamorphosis due to xyloglucan dissolution and matrix swelling, enzymatic hydrolysis of the polysaccharide and concomitant drug release due to matrix erosion and simultaneous drug diffusion. The model was fitted to data of reducing sugar equivalents in the medium reflecting matrix erosion and released drug amount. Enzymatic reaction parameters and reasonable values of medium ingress velocity, xyloglucan dissolution rate constant and drug diffusion coefficient were deduced that provided an adequate approximation of the data. Erosion was shown to be the overwhelmingly dominant drug release mechanism while the role of diffusion marginally increased at low enzyme concentration and high drug solubility. Changing enzyme concentration had a rather weak effect on matrix erosion and drug release rate as demonstrated by model simulations supported by experimental data, while xyloglucan dissolution was slow and had a stronger effect on the rate of the process. Therefore, reproducible colonic drug delivery not critically influenced by inter- and intra-individual variation of microbial enzyme activity may be projected.

Influencing Factors, Risk Assessment, and Source Identification of Heavy Metals in Purple Soil in the Eastern Region of Guang’an City, Sichuan Province, China

Soil heavy metal contamination poses a significant threat to both environmental health and ecological safety. To investigate the influencing factors, ecological hazards, and sources analysis of heavy metals in purple soil, 27 sets of soil samples were collected from varying genetic horizons within Guang’an City, and the contents of As, Cd, Cu, Cr, Hg, Ni, Pb, and Zn were analyzed. The results indicated higher concentrations of heavy metals in soil A horizon, compared to that of C horizon. The relevance analysis indicated that the soil’s heavy metals were strongly correlated with the soil’s physicochemical properties. The enrichment factor, pollution load index, and potential risk index highlighted slightly to severely polluted levels of soil Cd and Hg, which significantly contribute to the ecological hazards posed by soil heavy metals. The potential source of heavy metals analyzed using the APCS-MLR model identified both anthropogenic inputs and natural sources as primary contributors to heavy metal presence in soils. The Cu, Cr, Ni, Pb, and Zn contents in the samples from different genetic horizons were chiefly influenced by natural sources, such as soil matrix erosion and weathering, while the concentrations of Cd and Hg were largely affected by anthropogenic activities, specifically coal combustion and agriculture. Conversely, the As content was found to be influenced by a combination of both factors. Anthropogenic activities greatly impacted soil heavy metals at various depths within the study area, thereby underscoring the importance of monitoring these heavy metals. The findings gained from this research can give a scientific basis for the potential utilization of purple soil.

Influence of Casting Variables on Release Kinetics of Orally Disintegrating Film.

As a new form for supplying vitamin C, orally disintegrating films (ODFs) were developed C based on hyaluronic acid (HA) under varying casting conditions and the properties were analyzed. The films with different thicknesses (2, 3, and 8 mm, for CT2, CT4, and CT8, respectively) were produced by adjustments made to casting height. Two types of 8 mm thick ODFs produced by single or double casting (4 + 4 mm for CTD4+4) methods were also compared. As film thickness increased, water vapor permeability and tensile strength also increased. Even at equal thickness, manufacturing with double casting exhibited a stronger texture and reduced disintegration compared to single casting. All ODFs met the World Health Organization's recommended daily vitamin C intake (45 mg/day) with a single sheet. Films showed over 80% dissolution in various solvents, adhering to the Hixson-Crowell cube root law, indicating vitamin C release occurred via porous penetration of the eluate. For CT2, CT4, and CTD4+4, vitamin C release was primarily governed by diffusion within the gel matrix and HA erosion. However, for CT8, HA erosion-induced release somewhat dominated. Based on the sensory test, it seems desirable to adjust the thickness of the film to 2 or 4 mm, because a thickness greater than that increased the foreign body sensation due to prolonged residence in the oral cavity.

Cryo-Milled β-Glucan Nanoparticles for Oral Drug Delivery.

Gemcitabine is a nucleoside analog effective against a number of cancers. However, it has an oral bioavailability of less than 10%, due to its high hydrophilicity and low permeability through the intestinal epithelium. Therefore, the aim of this project was to develop a novel nanoparticulate drug delivery system for the oral delivery of gemcitabine to improve its oral bioavailability. In this study, gemcitabine-loaded β-glucan NPs were fabricated using a film-casting method followed by a freezer-milling technique. As a result, the NPs showed a small particle size of 447.6 ± 14.2 nm, and a high drug entrapment efficiency of 64.3 ± 2.1%. By encapsulating gemcitabine into β-glucan NPs, a sustained drug release profile was obtained, and the anomalous diffusion release mechanism was analyzed, indicating that the drug release was governed by diffusion through the NP matrix as well as matrix erosion. The drug-loaded NPs had a greater ex vivo drug permeation through the porcine intestinal epithelial membrane compared to the plain drug solution. Cytotoxicity studies showed a safety profile of the β-glucan polymers, and the IC50s of drug solution and drug-loaded β-glucan NPs were calculated as 228.8 ± 31.2 ng·mL-1 and 306.1 ± 46.3 ng·mL-1, respectively. Additionally, the LD50 of BALB/c nude mice was determined as 204.17 mg/kg in the acute toxicity studies. Notably, pharmacokinetic studies showed that drug-loaded β-glucan NPs could achieve a 7.4-fold longer T1/2 and a 5.1-fold increase in oral bioavailability compared with plain drug solution. Finally, in vivo pharmacodynamic studies showed the promising capability of gemcitabine-loaded β-glucan NPs to inhibit the 4T1 breast tumor growth, with a 3.04- and 1.74-fold reduction compared to the untreated control and drug solution groups, respectively. In conclusion, the presented freezer-milled β-glucan NP system is a suitable drug delivery method for the oral delivery of gemcitabine and demonstrates a promising potential platform for oral chemotherapy.

Excellent cyclic ablation resistance of MoAlB ceramics under nitrogen plasma flame at 2000 °C

Thermal protection materials (TPMs) are crucial in advancing aerospace technology. In order to explore the applicability limits and reusability of MoAlB ceramics used as TPMs, the cyclic ablation performance and mechanisms were studied in a nitrogen plasma flame at about 2000 °C. After 1 to 5 ablation cycles (5 min per cycle), MoAlB ceramics retained their structural integrity. The linear and mass ablation rates were measured as 4.73 µm/s and 2.98 mg/s, respectively, after five ablation cycles (total of 25 min). The ablation resistance of MoAlB ceramics was primarily ascribed to the oxidation layer formed through their decomposition and oxidation. As the cycles extended, the plasma flame gradually damaged the oxide layer and led to the erosion and failure of the MoAlB matrix. Nevertheless, MoAlB ceramics exhibit exceptional resistance against cyclic and long-duration ablation, rendering it a highly promising application for TPMs.

Corrosion behavior of precracked SiCf/SiC composites under 1200–1300°C Na2SO4‐wet‐oxygen environment

AbstractSiCf/SiC composites, as promising materials for the hot‐section components of turbine engines, are susceptible to hot corrosion due to the steam environments. Especially, under rotational and thermal stress, numerous microcracks may be generated in the SiCf/SiC ceramic matrix, which can trigger the rapid invasion of corrosive gases and deteriorate the composite mechanical properties. Therefore, it is of great importance to investigate the degradation mechanisms of SiCf/SiC with precracks existing. Here, the corrosion behavior of precracked SiCf/SiC in the Na2SO4‐wet‐oxygen environment was evaluated. By comparing mechanical evolution under different corrosion conditions, microfailure mechanisms of SiCf/SiC were revealed. The results indicate that brittle cracking of the matrix and oxidation erosion of fibers are the key factors in reducing the tensile strain of composites. Specifically, the composite damage resistance increases at 67 MPa‐1300°C. At this point, the prestress level is moderate and close to the matrix cracking limit. The prefabricated microcracks can be healed at 1300°C by liquid oxidation products, which hinders cracks bridging large‐scale. This study is conducive to a better understanding of failure mechanisms of SiCf/SiC in complex service environments.

Modification of the swelling behavior of a hydrophilic polymer as an approach to maintaining a constant gel layer thickness

The objective of the present study was to screen some ionic polymers that can modify the swelling and erosion characteristics of a hydrophilic polymer (HPMC) and thereby help provide constant drug release. It was hypothesized that the hydrophilic polymer's swelling rate and erosion of matrices could be modified by adding an ionic polymer, as the two will form a hydrogen bond. Methocel™ K4M (HPMC) was selected as the hydrophilic polymer. NaCMC, Eudragit® S100, and Eudragit® L100 were selected as anionic polymers. Eudragit® RSPO, Eudragit® RLPO and Eudragit® EPO were selected as cationic polymers. Various techniques were used to characterize the rate of swelling, gel layer thickness, and erosion of matrices of HPMC-ionic polymer combinations (3:1 ratio). Fourier-transform infrared spectroscopy was used to study HPMC-ionic polymer interaction. A texture analyzer was used to investigate the change in gel layer thickness and firmness of matrices during dissolution study over time. The stereo microscopic examination provided a structural change in matrices during swelling. Of all the matrices, the HPMC-Eudragit® RSPO combination showed simultaneous swelling and matrix erosion, resulting in constant gel layer thickness (diffusional path length) for 12 h.

RGD-modified solid lipid nanoparticles improve oral doxorubicin absorption: In vitro and in vivo study

ObjectiveDoxorubicin (DOX), an effective antitumor drug, is widely used in cancer treatment. However, DOX has low oral bioavailability. Owing to its ability to specifically bind the β1 receptor on the surface of M cells, promote the phagocytosis of drugs by M cells, and improve the oral efficacy of drugs, arginine-glycine-aspartic peptide (RGD) is used to modify the oral nanodrug delivery system. MethodsAn emulsion solvent evaporation method was used to prepare DOX-loaded solid lipid nanoparticles (DOX-SLNs), which were further modified with RGD (RGD-DOX-SLNs) by noncovalent interactions. The physicochemical properties, dissolution rate, and cytotoxicity of the SLNs were investigated. An in vitro transparency experiment was performed using the follicle-associated epithelium (FAE) model. In addition, oral bioavailability and gastrointestinal (GI) mucosal irritation were evaluated in rats. ResultsThe cumulative release percentage of DOX at pH 1.2 decreased significantly when DOX was incorporated into the SLNs, which may be dependent on drug diffusion and matrix erosion mechanisms. The cell toxicity was low in Caco-2 cells. No GI mucosal irritation was found in rats. The cellular uptake of RGD-DOX-SLNs in the FAE model was higher than in Caco-2 model. Compared with the DOX group, the area under the plasma concentration-time curve (AUC) of DOX in the RGD-DOX-SLNs group increased 2.25-fold after oral administration to rats. ConclusionsRGD-DOX-SLNs improved DOX transport in the FAE model and enhanced the oral bioavailability of DOX in rats.

A comprehensive review on sustained release tablets

Sustained release is a method to reduce therapeutic drugs side effects by preventing the therapeutic concentration of the drug from fluctuating in the body. Sustained release is used to describe a pharmaceutical dosage form formulated to retard the release of therapeutic drug so that it remains in the systemic circulation for prolonged time and its plasma profile is sustained in duration. Sustained release drug delivery system has been formulated in form of tablets to slow down release of drug from tablets. It works on various mechanisms to control the release rate of drugs. Formulation approaches that have been utilized are drug dissolution, drug diffusion, matrix erosion. Present review work deals with the different aspect of the sustained release tablets.

TPGS/soluplus® blended micelles: an effective strategy for improving loading capacity of ferroptosis inducer erastin

Erastin is the most classical small molecular ferroptosis inducer but its clinical application is hindered due to its poor solubility. Nanotechnology has been used to improve ferroptosis inducer erastin’s solubility. The recently reported erastin-incorporated nanosystems (e.g., nanoparticulate ferritin, poly(ethylene glycol) methyl ether-blockpoly(lactide-co-glycolide) (mPEG-PLGA) nanoparticle, exosome, and liposome) could to some degree elevate its solubility, but were still poor in loading capacity. To be specific, the maximum entrapment efficiency and drug loading in previous studies were approximately 36% and 3.7%, respectively. In order to improve drug loading capacity, we constructed a novel carrier based on Vitamin E d-α-Tocopherol polyethylene glycol 1000 succinate (TPGS) and polyvinyl caprolactam-polyvinyl acetate-polyethylene glycol graft copolymer (Soluplus®) blended micelles. The erastin@TPGS/Soluplus® micelles were prepared by thin film hydration method, and formulation details including dosage of Soluplus®, the weight ratio of TPGS to Soluplus®, the weight ratio of erastin to TPGS/Soluplus® were optimized. The physicochemical properties of the erastin micelles were measured by DLS, TEM, FTIR, and TG-DSC analysis. The products exhibited a nanoscale and uniform particle size (78.11 ± 0.54 nm) and neutral surface charge (-0.43 ± 0.32 mV). Significantly improved entrapment efficiency (89.63 ± 1.81%) and drug loading rate (10.03 ± 0.14%) were obtained, which was over 2-fold of current reports. The in vitro release study demonstrated that erastin could release in a sustained yet complete manner, and the drug release might be governed by multiple mechanisms including anomalous diffusion of non-Fickian diffusion, matrix erosion and sustained release. In summary, this proposed erastin nanosystem provides a new strategy for improving loading capacity, and may probably augment ferroptosis-inducing therapy for cancer treatment.

Grafted tamarind kernel polysaccharide based Al3+ cross-linked hydrogel matrices for sustained release of drug in the gastrointestinal milieu

Ionically cross-linked hydrogel serves as an excellent matrix material for the sustained delivery of drugs. Tablets prepared with tamarind kernel polysaccharide (TKP) as the sole matrix material could not provide sustained release of the incorporated drugs. The purpose of the work was to modify TKP and development of ionically cross-linked hydrogel matrix tablets for sustained drug delivery. Grafting of TKP was performed with methacrylic acid (MAA) following the free radical polymerization technique. Hydrogel matrix tablets using Al3+ ion cross-linked grafted TKP were prepared by direct compression method. Al3+ ions were found to considerably influence the erosion, swelling, and paracetamol release from the matrix tablet. Retardation of the erosion, swelling, and paracetamol release was observed with increasing the concentration of Al3+ ions. The hydrogel matrix tablets showed a slow release of drugs in an acidic medium and a relatively faster drug release in an alkaline medium. The optimized formulation having a co-polymer/aluminium hydroxide (Al(OH)3) ratio of 1:1, exhibited sustained drug release action for more than 10 h with lower swelling and erosion of the gel matrix. We conclude that Al3+ ion cross-linked grafted TKP is an excellent matrix material for sustained delivery of drugs in the gastrointestinal milieu.

Effect of Ni content on the corrosion behavior of Mo2NiB2–Ni cermet in H2SO4 solution

To promote the utilization of Mo2NiB2–Ni cermet under sulfuric acid drew corrosion conditions, it is essential to elucidate the resistance mechanism of these cermets to sulfuric acid corrosion. In this study, the corrosion behavior of Mo2NiB2–Ni cermets with different Ni content in 90 wt % H2SO4 solution at 110 °C was investigated, and the corrosion resistance mechanism was analyzed. The results reveal that the corrosion weight losses and corrosion rates of the cermets decreased with increasing Ni content. Mo2NiB2–Ni cermets with higher Ni contents exhibited improved corrosion resistance. This improvement can be attributed to the generation of a considerable amount of NiSO4 corrosion products from the Ni binder phase corroded by H2SO4, which led to the subsequent formation of a large-scale, flat, and dense corrosion products layer with a certain thickness. This effectively prevented further erosion of the inner matrix and improved the corrosion resistance of the cermet. Additionally, the electrochemical results indicate that the corrosion product layer hindered the passage of electric charges through the layer, which inhibited the corrosion reaction.

Design and evaluation of gastro-swelling/gastro-floating sustained-release tablets of brivaracetam for epilepsy therapy

To prolong the absorption of the drug and achieve the effect of gastric retention, new brivaracetam tablets together with the characteristics of rapid swelling and sustained floating have been developed here. The tablets were optimized and prepared by direct compression techniques using Kollidon® SR and cross-linked polyvinylpyrrolidone (PVPP) XL as the matrix and disintegrant respectively, and carbomer 71G NF and polyethylene oxide (PEO) N60K as the gel materials to achieve sustained release effect. The characteristics of static expansion, floating time, drug release and dynamic swelling performance in vitro of the tablets were evaluated. The optimized formulations (F5 and F10) exhibited satisfactory swelling and floating properties, mechanical strength, and in vitro sustained-release characteristic with diffusion and matrix erosion mechanisms. X-ray images of beagle dogs showed that the tablet F5 could be retained in the stomach for more than 6 h. Furthermore, the pharmacokinetic studies in volunteers exhibited that the bioavailability of F5 and F10 was 95.70% (90% CI, 83.80%-109.28%) and 103.39% (90% CI, 87.61%-122.01%), respectively, relative to commercial tablets, with Tmax prolonged, demonstrating an excellent sustained-release effect. Therefore, the present system can reduce dosing frequency and improve patient compliance, which is expected to be a promising treatment option for epilepsy patients.

Model predictive in vitro dissolution testing in pharmaceutical continuous manufacturing: An equivalence study

AbstractA predictive mathematical model for tablet dissolution was developed and implemented in an end‐to‐end integrated continuous manufacturing pilot plant. The tablets were produced for immediate release with a proprietary extrusion‐molding‐coating (EMC) unit operation. Besides the mass balance of API solute in the buffer solution, the model consisted of the dissolution, diffusion, and population balance of API particles in the swollen tablet, which was mainly controlled by the swelling and erosion of the polymeric excipient matrix. An equivalence study was investigated by comparing the model prediction to the experiments that were conducted according to USP42‐NF37 General Chapter &lt;711&gt; Dissolution, during which the drug dose level was varied in a range from 60 to 80 wt%. Consistent equivalence was demonstrated with the similarity factor f2 &gt; 50 for all sampled tablets. Concluding remarks and industrial perspectives on model predictive in vitro dissolution testing are provided.

HEAVY METALS CONTAMINATION OF WATER AND FISH- A REVIEW

Water is a vital resource for all kinds of lives. Heavy metals (HM) generally enter the aquatic environment through natural (atmospheric deposition, erosion of geological matrix) or anthropogenic activities caused by industrial effluent, domestic sewage, mining and agricultural wastes. Tanning generally requires using a heavy chemical that contains chromium, cadmium etc. It was observed that these industrial wastes are discharged, without proper treatment, into small waterways, which subsequently adjoin the rivers and dams. Using agricultural chemicals and fertilizers also contributes to the chemical contamination of the aquatic environment. Discharging untreated sewage into the waterways introduce pathogenic microorganism into the marine environment, among other reasons, which has drawn the attention of researchers to the possibility of having the aquatic organism edible by humans (mostly fish) be contaminated by heavy metals and microorganisms, which have been confirmed to cause short- and long-term health hazards. Fish, one of the primary aquatic organisms in the food chain, may often accumulate large amounts of metals, which can later intoxicate humans after consumption. Humans can also be intoxicated by directly consuming untreated water contaminated with heavy metals. This review focused on the aquatic contamination of different heavy metals in water and fish and also suggested some recommendations to minimize the marine environment's toxicity.

Tablet formulation with dual control concept for efficient colonic drug delivery

Aim of this study was to develop a tablet formulation for targeted colonic drug release by implementing two control mechanisms: A pH-sensitive coating layer based on Eudragit® FS 30 D to prevent drug release in the upper gastrointestinal tract, combined with a matrix based on plant-derived polysaccharide xyloglucan to inhibit drug release after coating removal in the small intestine and to allow microbiome triggered drug release in the colon. In vitro dissolution tests simulated the passage through the entire gastrointestinal tract with a four-stage protocol, including microbial xyloglucanase addition in physiologically relevant concentrations as microbiome surrogate to the colonic dissolution medium. Matrix erosion was monitored in parallel to drug release by measurement of reducing sugar equivalents resulting from xyloglucan hydrolysis. Limited drug release in gastric and small intestinal test stages and predominant release in the colonic stage was achieved. The xyloglucan matrix controlled drug release after dissolution of the enteric coating through the formation of a gummy polysaccharide layer at the tablet surface. Matrix degradation was dependent on enzyme concentration in the colonic medium and significantly accelerated drug release resulting in erosion-controlled release process. Drug release at physiologically relevant enzyme concentration was completed within the bounds of colonic transit time. The dual control concept was applicable to two drug substances with different solubility, providing similar release rates in colonic environment containing xyloglucanase. Drug solubility mechanistically affected release, with diffusion of caffeine, but not of 5-ASA, contributing to the overall release rate out of the matrix tablet.