Release Of Pellets Research Articles

Fate of synthetic chemicals in the agronomic insect pest Spodoptera littoralis: experimental feeding-contact assay and toxicokinetic model.

Insecticides prevent or reduce insect crop damage, maintaining crop quality and quantity. Physiological traits, such as an insect's feeding behavior, influence the way insecticides are absorbed and processed in the body (toxicokinetics), which can be exploited to improve species selectivity. To fully understand the uptake of insecticides, it is essential to study their total uptake and toxicokinetics independent of their toxic effects on insects. We studied the toxicokinetics (TK) of insecticidally inactive test compounds incorporating agro-like structural motifs in larvae of the Egyptian cotton leafworm (Spodoptera littoralis,Lepidoptera),and their distribution across all biological matrices, using laboratory experiments and modeling. We measured Spodoptera larval behavior and temporal changes of whole-body concentrations of test compounds during feeding on treated soybean leaf disks and throughout a subsequent depuration period. Differences in the distribution of the total quantities of compounds were found between the biological matrices leaf, larva, and feces. Rate constants for uptake and elimination of test compounds were derived by calibrating a toxicokinetic model to the whole-body concentrations. Uptake and elimination rate constants depended on the physicochemical properties of the test compounds. Increasing hydrophobicity increased the bioaccumulation potential of test compounds. Incomplete quantities in larval matrices indicated that some compounds may undergo biotransformation. As fecal excretion was a major elimination pathway, the variable time of release and number of feces pellets led to a high variability in the body burden. We provide quantitative models to predict the toxicokinetics and bioaccumulation potential of inactive insecticide analogs (parent compounds) in Spodoptera.

Impact of breech geometry and propellant flow on the release of large pellets for the ITER disruption mitigation system

Studies have been performed on the release mechanism for large pellets using high pressure gas in a shattered pellet injector. Typically, pellets are dislodged from the cryogenic surface and accelerated down a barrel using high pressure gas delivered by a fast-acting propellant valve. The pellets impact an angled surface which shatters the pellet into many small fragments before entering the plasma. This technique was initially demonstrated on DIII-D (Commaux et al 2016 Nucl. Fusion 56 046007) and is now deployed on JET, KSTAR, ASDEX-Upgrade, and other tokamaks around the world in support of ITER’s disruption mitigation system design and physics basis. The large hydrogen, 28.5 mm diameter, 2 length-to-diameter ratio, pellets foreseen for ITER SPI operation have low material strength and low heat of sublimation, which cause the pellets to be fragile and highly reactive to the impact of warm propellant gas. Due to the size of the pellets, significantly more propellant gas is required to dislodge and accelerate them. This creates a potentially significant propellant gas removal issue as 2–6 bar-L of gas is expected to be required for release and speed control. The research presented in this paper is an in-depth exploration of the parameters that are keys to reliable pellet release and speed control. Computational fluid dynamics (CFD) modeling of propellant flows through various breech designs was conducted to determine the force generated on the back surface of a pellet. These simulations assumed the use of the ORNL designed flyer plate valve. CFD modeling combined with experimental measurements provide adequate insight to determine a path to an optimal valve and breech design for ITER SPI pellet release and speed control while minimizing propellant gas usage.

Pengaruh Desain Punch Terhadap Mutu Fisik dan Disolusi Tablet MUPS Metformin HCl

The compaction of multi-unit pellet system (MUPS) into tablets is a potential alternative for sustained release drugs. Tableting tools (punch and die) affect the compaction process and quality of MUPS tablets. The punch design intends to preserve the desired drug release of compacted pellets. This study aims to investigate the effect of two punch shapes, the flat face radius edge (FFRE) and concave-faced punch (concave), each at two different cup depths, on the physical properties and release profile of metformin HCl MUPS tablets. Drug release parameters, t50 values, showed that the metformin HCl released from MUPS tablets was faster than the uncompacted sustained release pellets. The similarity of the dissolution profile (f2) between MUPS tablets and uncompacted metformin HCl pellets was lower than 50 as the minimum acceptance value. The tablet tensile strength obtained was below the requirements (<1.7 MPa). Tablet disintegration time was approximately less than 2 minutes. In conclusion, drug release profile of the MUPS tablets showed damage of the pellets due to compaction process. Nevertheless, pellets compacted at low compaction pressure using FFRE with a deeper cup depth (size 0.80 mm) showed a slightly better protection compared to other punch shapes and cup depth sizes applied.

Recent Advances in Improving the Bioavailability of Hydrophobic/Lipophilic Drugs and Their Delivery via Self-Emulsifying Formulations

Formulations based on emulsions for enhancing hydrophobic and lipophilic drug delivery and its bioavailability have attracted a lot of interest. As potential therapeutic agents, they are integrated with inert oils, emulsions, surfactant solubility, liposomes, etc.; drug delivering systems that use emulsion formations have emerged as a unique and commercially achievable accession to override the issue of less oral bioavailability in connection with hydrophobic and lipophilic drugs. As an ideal isotropic oil mixture of surfactants and co-solvents, it self-emulsifies and forms fine oil in water emulsions when acquainted with aqueous material. As droplets rapidly pass through the stomach, fine oil promotes the vast spread of the drug all over the GI (gastrointestinal tract) and conquers the slow disintegration commonly seen in solid drug forms. The current status of advancement in technologies for drug carrying has promulgated the expansion of innovative drug carriers for the controlled release of self-emulsifying pellets, tablets, capsules, microspheres, etc., which got a boost for drug delivery usage with self-emulsification. The present review article includes various kinds of formulations based on the size of particles and excipients utilized in emulsion formation for drug delivery mechanisms and the increase in the bioavailability of lipophilic/hydrophobic drugs in the present time.

Preparation, characterization, and in vitro release of microencapsulated essential oil hydroxyapatite pellets filled into multifunctional capsules

Oregano essential oil (EO)–loaded pellets were prepared using calcium phosphate substrates of different specific surface areas (Sw) and as binders EO in water emulsions with low or high EO content, stabilized with polysaccharides (PSC) or a combination of PSC-Eudragit® L100-55 (PSC-PLM) encapsulants. Tri-cafos® 250 with high Sw gave higher EO loading and more spherical pellets with narrow size distribution. These were filled into the following hard-shell capsules: gelatin, hydroxypropyl-methyl cellulose (HPMC) based immediate release (Vcaps® plus), gastro-resistant (DRcaps®) and enteric release (Vcaps® enteric), and pullulan (Plantcaps®). FTIR and Raman spectroscopy showed H-bonding between PSC and EO and between PSC and PLM. Pellet mechanical strength decreased with EO content and pellets made with PSC emulsions were stronger than PSC-PLM pellets proving PSC binder ability. Disintegration and release of EO from capsules filled with immediate release pellets (PSC) or enteric pellets (PSC-PLM) were tested sequentially in pH 1.2 and 6.8. Capsule shell influenced disintegration and release. The release of EO from the PSC pellets within 1 h, at pH 1.2 was from gelatin 82%/85% (for low/high EO emulsions) but from Vcaps® plus and Plantcaps® it was lower, 36%/38% and 45%/70% respectively. DRcaps® and Vcaps® enteric capsules confirmed gastro-resistance. The release of enteric (PCS-PLM) pellets was: from gelatin and Vcaps® plus capsules 21%/23% and 20%/21% respectively, but from Plantcaps® 61%/62%, indicating deactivation of Eudragit® L100-55 functionality in the last case. In all cases, release was complete after 180 min, but release of enteric pellets from Vcaps® plus was slower than from gelatin capsules due to the presence of HPMC.

IMPROVED DISSOLUTION OF IBUPROFEN BY SOLID DISPERSION SYSTEM AND THE INCORPORATION INTO PELLETS 

Background and purposes: Ibuprofen is a commonly used NSAID for anti-inflammatory, antipyretic, analgesic, and antiplatelet agents. However, Ibuprofen is poorly soluble in water and its bioavailability is low. Pellets containing the solid dispersion system are considered as a drug delivery system with many outstanding advantages such as improving the stability, the solubility as well as the dissolution rate, thus increasing the bioavailability. The aim of this study was to formulate pellets containing the solid dispersion system of ibuprofen, and to evaluate the physico-chemical properties of prepared pellets. Materials and methods: Ibuprofen, PVP K30 were used in this study. Pellets were prepared by the layering technique based on the solvent method used in preparing the solid dispersion system of Ibuprofen. Results: The preparation of a solid dispersion system of ibuprofen using PVP K30 as a carrier helps to improve both the appearance and the drug solubility at the optimal drug: PVP K30 ratio of 1:10 (w/w). Pellets have a spherical shape with the size in the range of 0.7-1.0 mm, the coating efficiency of 33.27%, the drug release of pellets was 7-fold higher than that of the raw material after 60 min. Conclusions: The incorporation of Ibu-loaded solid dispersion system into pellets contributed to enhance the dissolution of Ibuprofen as compared with the raw material. Key words: Ibuprofen, pellet, solid dispersion system.

FORMULATION AND EVALUATION OF BUDESONIDE PELLETS CONTAINING NATURAL GUMS FOR COLON TARGETING

Pellets formulation with natural gums. The formulation of an enzyme as well as pH dependant pellets containing natural gums such as Mornings oleifera gum Lam. (MOG) and Cyamopsis tetragonolobus gum Taub. (CTG) were used for enzyme dependant release and further coating is provided to shows colon-specific delivery. Extrusion and spheronization techniques were used for the preparation of pellets. Pellets of budesonide evaluated for various properties such as flow behavior, physical properties such as sphericity, roundness, aspect ratio, hardness, and friability also investigated in vitro and in vivo targeting in rabbit. Preparation of pellets was done by using extrusion and spheronization method with the use of optimized concentration of gums those were 7.5% and 10% for CTG and MOG respectively and proportion of solvent mixture of water and Isopropyl alcohol in the ratio of 80:20. Pellets of budesonide evaluated for various properties includes flow behavior, physical properties such as sphericity, roundness, aspect ratio, hardness, and friability and found that all properties as per official limit also in vitro release study found that release of uncoated pellets in a sustained manner in 0.1N HCl for 2h due to swelling of natural gum, therefore further step of the coating was done in fluidized bed coater to prevent the release of drug in the upper part of GIT and after coating found that In vitro release of drug at the colonic environment and it confirmed with in vivo investigation in rabbit with X-ray examination of targeting and found that pellets reach at colonic part without disintegration. The use of natural gums for preparation of pellets in optimized concentration and wetting agent produce a formulation with all required chemical and physical properties and it gives effective in vitro release and also shows In vivo targeting in rabbit and due to use of natural gum for preparation of pellets also reduce some problems of metabolism of synthetic excipients.

Heats of wetting and sorption for wood pellets

Wood pellets have become a flagship biofuel in transitioning from coal-based heat and power generation to renewable energy. However, the hygroscopic nature of wood pellets is a long-standing challenge in storing and transporting this commodity. The heat of moisture sorption contributes to the self-heating and spontaneous combustion of wood pellets. The objective of this paper is to investigate the evolution of heat in moistened pellets and to compare them to that of wood chips. Wood pellets at several moisture content levels were immersed in liquid water and the rise in the pellets’ temperature was recorded. The calorimetric method was used to calculate the heat of wetting for the immersed pellets. The heat of wetting was at its maximum for completely dry pellets. The heat of wetting decreased linearly as the moisture content increased towards a fiber saturation point of about 0.17 (decimal dry basis). Statistically, the maximum heat of wetting of pellets is the same as that of wood chips. However, the rate of heat release of pellets is twice of that of chips.

Quantification of porogen effect on the drug release from single- and multi-layered ethylcellulose coated pellets containing single or combined drugs

The aim of this work was to develop a mathematical model to estimate the drug release from a conventional single-compartment reservoir pellet and extend its applicability to multi-compartment reservoir pellets. Conventional pellets were prepared by layering the drug onto starter-core then applying various ethylcellulose/HPC coatings for drug release control. Multi-layered pellets comprised a first drug layer of propranolol HCl (D1) followed by a first controlled release coating (C1) and consecutively a second drug layer of carbamazepine or caffeine (D2) and then a second controlled-release coating (C2). Drug release from single- and multi-compartment pellets generally increased with an increase of the water-soluble HPC in the coatings. The response described a sigmoidal curve, which agreed with a cumulative normal distribution function. The developed mathematical model facilitated quantification of the drug release of pellets as a function of the porogen content and the coating level. Additionally, the model was applied successfully in multi-compartment pellets to calculate theses effects on the release of drugs with a broad range of aqueous solubility.

Effect of Cross Linking on Evaluation of Chitosan Coated Pellets of Glipizide

The objective of the current work is to develop and evaluate the effect of cross linking on drug release of chitosan pellets of Glipizide. Hence the present work was aimed to formulate glipizide pellets with a view to achieve and to maintain the plasma concentration for considerable period by controlling the release so to decrease the occurrence of doses and also to recover the patient fulfillment. Here the pellets of glipizide are designed by Pan Coating technique with solution layering with and without cross linking by Gluteraldehyde effectively. Then the optimized formulations are aimed to study the effects of polymer and cross linking on different evaluation parameters including the drug release study. Finally the conclusion was to arrive at better formulation based on comparison amongst the studied ones.

Self-Micro-Emulsifying Controlled Release of Eugenol Pellets: Preparation, In vitro/In vivo Investigation in Beagle Dogs.

This report aimed to formulate self-micro-emulsifying (SMEDDS) controlled-release pellets delivery system to improve aqueous solubility and in vivo availability of eugenol, a main constituent of clove oil with multiple pharmacological activities. The optimal formulation of eugenol-SMEDDS was eugenol: ethyl oleate: cremophor EL: 1, 2-propylene glycol at the ratio of 5:5:12:8. The SMEDDS were observed under transmission electron microscopy (TEM), and the size distribution was measured with dynamic laser light scatting (DLS). The particle size, index of dispersity (PDI), and zeta potential (Z-potential) were 68.8 ± 0.1nm, 0.285 ± 0.031, and - 11.62 ± 0.63mV, respectively. Eugenol-SMEDDS exhibited substantial increased in vitro dissolution compared with the free eugenol. The eugenol-SMEDDS sustained-release pellets (eugenol-SMEDDS-SR pellets) comprising of eugenol-SMEDDS, hydroxypropyl methylcellulose (HPMC), microcrystalline cellulose (MCC), and ethyl cellulose (EC) coats were obtained via extrusion spheronization technique. Consequently, the obtained pellets observed under scanning electron microscopy (SEM) showed spherical shape with smooth surface, desirable drug loading capacity (7.18 ± 0.17%), greater stability, and controlled release. Meanwhile, the oral test showed that bioavailability of eugenol in pellets was highly improved 23.6-fold to the free eugenol. Overall, these results suggested that the improvement of the oral bioavailability of eugenol-SMEDDS-SR could be due to the successful incorporation of the drug into SMEDDS.

Pelagic Iron Recycling in the Southern Ocean: Exploring the Contribution of Marine Animals

The availability of iron controls primary productivity in large areas of the Southern Ocean. Iron is largely supplied via atmospheric dust deposition, melting ice, the weathering of shelf sediments, upwelling, sediment resuspension, mixing (deep water, biogenic, and vertical mixing) and hydrothermal vents with varying degrees of temporal and spatial importance. However, large areas of the Southern Ocean are remote from these sources, leading to regions of low primary productivity. Recent studies suggest that recycling of iron by animals in the surface layer could enhance primary productivity in the Southern Ocean. The aim of this review is to provide a quantitative and qualitative assessment of the current literature on pelagic iron recycling by marine animals in the Southern Ocean and highlight the next steps forward in quantifying the retention and recycling of iron by higher trophic levels in the Southern Ocean. Phytoplankton utilize the iron in seawater to meet their metabolic demand. Through grazing, pelagic herbivores transfer the iron in phytoplankton cells into their body tissues and organs. Herbivores can recycle iron through inefficient feeding behavior that release iron into the water before ingestion, and through the release of fecal pellets. The iron stored within herbivores is transferred to higher trophic levels when they are consumed. When predators consume iron beyond their metabolic demand it is either excreted or defecated. Waste products from pelagic vertebrates can thus contain high concentrations of iron which may be in a form that is available to phytoplankton. Bioavailability of fecal iron for phytoplankton growth is influenced by a combination of the size of the fecal particle, presence of organic ligands, the oxidation state of the iron, as well as biological (e.g., remineralization, coprochaly, coprorhexy, and coprophagy) and physical (e.g., dissolution, fragmentation) processes that lead to the degradation and release of fecal iron. The flux of dissolved iron from pelagic recycling is comparable to other sources in the region such as atmospheric dust, vertical diffusivity, vertical flux, lateral flux and upwelling, but lower than sea ice, icebergs, sediment resuspension, and deep winter mixing. The temporal and seasonal importance of these various factors requires further examination.

The unaccountability case of plastic pellet pollution

Plastic preproduction pellets are found in environmental samples all over the world and their presence is often linked to spills during production and transportation. To better understand how these pellets end up in the environment we assessed the release of plastic pellets from a polyethylene production site in a case study area on the Swedish west coast. The case study encompasses; field measurements to evaluate the level of pollution and pathways, models and drifters to investigate the potential spread and a revision of the legal framework and the company permits. This case study show that millions of pellets are released from the production site annually but also that there are national and international legal frameworks that if implemented could help prevent these spills. Bearing in mind the negative effects observed by plastic pollution there is an urgent need to increase the responsibility and accountability of these spills.

Curcumin Pellets of Carboxymethylated Tamarind Seed Polysaccharide for the Treatment of Inflammatory Bowel Disease

Background and Objectives: Inflammatory Bowel Disease (IBD) is a group of inflammatory conditions of the colon and small intestine. Crohn's disease and ulcerative colitis are the principal types of inflammatory bowel disease. IBD is a complex disease which arises as a result of the interaction of environmental and genetic factors leading to immunological responses and inflammation in the intestine. Curcumin, a yellow coloring agent is used as a remedy for the treatment and prevention of inflammatory disease. Curcumin is safe, non-toxic, and mediates its anti-inflammatory effects through the down-regulation of inflammatory transcription factors, cytokines, redox status, protein kinases, and enzymes that all promote inflammation. Methods: An attempt was made to formulate sustained release pellets of curcumin using Carboxymethyl Tamarind Seed Polysaccharide (CMTSP). Solid dispersion of curcumin prepared using soluplus and incorporated into pellets for enhanced solubility and bioavailability. A central composite design was applied to study the effect of independent variables (amount of microcrystalline cellulose MCC and CMTSP) on crushing strength and drug release of pellets. In vivo study of solid dispersion loaded pellets revealed the presence of more amount of drug in plasma than pure drug loaded pellets. Result: Dissolution and absorption of curcumin were found to be increased by 1.5 and 2 fold, respectively. Conclusion: Carboxymethyl tamarind seed polysaccharide can be used successfully for colon targeted drug delivery system in the form of pellets. The percent permeability of pellets prepared by using solid dispersion was found to be more than pellets prepared by using pure drug. Curcumin has an advantageous safety profile as well as low relativecost, making it an attractive option for IBD patients. Keywords: Soluplus, carboxymethyl tamarind seed polysaccharide, extrusion-spheronization, solid dispersion pellets, inflammatory bowel disease, curcumin.

Lipids bearing extruded-spheronized pellets for extended release of poorly soluble antiemetic agent\u2014Meclizine HCl

BackgroundAntiemetic agent Meclizine HCl, widely prescribed in vertigo, is available only in immediate release dosage forms. The approved therapeutic dose and shorter elimination half-life make Meclizine HCl a potential candidate to be formulated in extended release dosage form. This study was aimed to develop extended release Meclizine HCl pellets by extrusion spheronization using natural and synthetic lipids. Influence of lipid type, drug/lipid ratio and combinations of different lipids on drug release and sphericity of pellets were evaluated.MethodsThirty two formulations were prepared with four different lipids, Glyceryl monostearate (Geleol®), Glyceryl palmitostearate (Precirol®), Glyceryl behenate (Compritol®) and Carnauba wax, utilized either alone or in combinations of drug/lipid ratio of 1:0.5–1:3. Dissolution studies were performed at variable pH and release kinetics were analyzed. Fourier transform infrared spectroscopy was conducted and no drug lipid interaction was found.ResultsSphericity indicated by shape factor (eR) varied with type and concentration of lipids: Geleol® (eR = 0.891–0.997), Precirol® (eR = 0.611–0.743), Compritol® (eR = 0.665–0.729) and Carnauba wax (eR = 0.499-0.551). Highly spherical pellets were obtained with Geleol® (Aspect ratio = 1.005–1.052) whereas irregularly shaped pellets were formed using Carnauba wax (Aspect ratio = 1.153–1.309). Drug release was effectively controlled by three different combinations of lipids: (i) Geleol® and Compritol®, (ii) Geleol® and Carnauba wax and (iii) Geleol®, Compritol® and Carnauba wax. Scanning electron microscopy of Compritol® pellets showed smooth surface with pores, whereas, irregular rough surface with hollow depressions was observed in Carnauba wax pellets. Energy dispersive spectroscopy indicated elemental composition of lipid matrix pellets. Kinetics of (i) Geleol® and Compritol® pellets, explained by Korsmeyer-Peppas (R2 = 0.978–0.993) indicated non-Fickian diffusion (n = 0.519-0.597). Combinations of (ii) Geleol® and Carnauba wax and (iii) Geleol®, Compritol® and Carnauba wax pellets followed Zero-order (R2 = 0.991–0.995). Similarity test was performed using combination of Geleol® and Compritol® (i) as a reference.ConclusionsMatrices for the extended release of Meclizine HCl from extruded-spheronized pellets were successfully formed by using three lipids (Geleol®, Compritol® and Carnauba wax) in different combinations. The encapsulated pellets of Meclizine HCl can be effectively used for treatment of motion sickness, nausea and vertigo for extended period of time.

FORMULATION AND EVALUATION OF NICORANDIL FLOATING PULSATILE PELLETS FOR CHRONOTHERAPEUTIC DRUG DELIVERY

The objective of the work was to develop nicorandil floating pulsatile pellets by pan coating technique where drug loaded pellets were coated with pH dependent polymer Eudragit S100 for chronotherapy of angina pectoris, an underlying cause of heart attack. These pellets were evaluated for micromeritics properties, particle size, percent entrapment efficiency, percent friability, in vitro floating ability, drug release and kinetics of pellets. The optimized batch exhibited good entrapment efficiency and flow properties, optimum friability and good floating property and released the drug at right time when symptoms are at peak level in early hours by maintaining required lag phase during floating in acidic medium for 5 hours, followed by burst release in simulated intestinal fluid (pH 7.4 phosphate buffer). It followed first order kinetics. Scanning Electronic Microscopy analysis of optimized batch revealed that the pellets were spherical in shape with smooth surface.

Optimize preparation parameters of colon-specific pellets of Angelica Sinensis Radix supercritical fluid extraction with response surface analysis methodology

To prepare pellets of supercritical fluid extraction (SFE) of Angelica Sinensis Radix by using the ionic crosslinking method, and the drug loading and encapsulation efficiency were used as the index to investigate the multiple factors which may impact the drug loading and encapsulation efficiency. Box-Behnken design and response surface analysis method were then taken to optimize the prescription of pellets and study the coating technology. Through the study on the release of pellets in vitro, an optimal coating technology and prescription of colon-specific pellets of Angelica Sinensis Radix SFE were selected and their colon targeting was evaluated. The optimal preparation parameters of pellets were determined as follows： 3% pectin; 4∶1 for pectin/lecithin; 4∶5 for pectin/SFE of Angelica Sinensis Radix; 4% zinc acetate solution as crosslinking agent, blending temperature 35 ℃, crosslinking temperature 35 ℃, crosslinking time 30 min; coating technology： coating material Eudragit FS 30D, 1.5% triethyl citrate and polyoxyethylene sorbitan monooleate（tween-80）, 1.2% monostearin and 15% coating weight gained. The colon-specific pellets of Angelica Sinensis Radix SFE prepared with optimized conditions were almost not released in simulated gastric fluid in 2 h, released less than 20% in simulated intestine fluid in 4 h, and released more than 90% in simulated colon fluid in 6 h, indicating that the colon-specific pellets of Angelica Sinensis Radix SFE had an excellent colon targeting property.

Synergistic effects of propagule pressure and trophic subsidies overcome biotic resistance to a non-native fish

A central question in invasion ecology is how non-native species develop sustainable populations from small numbers of introduced founders. As biotic resistance, propagule pressure and trophic subsidises affect the outcomes of introductions of non-native fish, their individual and combined effects were tested in experimental mesocosms using the model species Pseudorasbora parva, a highly invasive fish in Europe. Their effects were measured as the number of 0+ P. parva present per treatment at the end of one reproductive season. The control started with 8 mature individuals (equal sex ratio). There were seven treatments, comprising propagule pressure (16 individuals), biotic resistance (presence of a coexisting fish) and trophic subsidies (daily release of fishmeal pellets), and their combinations. Compared to the control, biotic resistance resulted in significantly reduced 0+ fish numbers, with stable isotope analysis (δ13C, δ15N; SIA) suggesting this was due to facultative piscivory by the coexisting fish. There were significantly elevated 0+ fish numbers in the trophic subsidy, with SIA suggesting the diet of co-existing fish now primary comprised the subsidy. There was no significant difference in 0+ fish number between the control and propagule pressure treatment. Whilst the effect of biotic resistance on 0+ fish number was reduced slightly with propagule pressure and also when the trophic subsidy was available, there were significantly increased numbers of 0+ fish present in the treatment where they acted in combination. Thus, their effects appeared synergistic, overcoming the biotic resistance and enabling greater numbers of 0+ P. parva to survive until the end of the reproductive season.

Evaluation of the effect of physical variables on in vitro release of diclofenac pellets using Box-Behnken design.

A Box-Behnken design was used for evaluation of Eudragit coated diclofenac pellets. The purpose of this work was to optimize diclofenac pellets to improve the physicochemical properties using experimental design. Diclofenac was loaded onto the non-pareil beads using conventional coating pan. Film coating of pellets was done at the same pan. The effect of plasticizer level, curing temperature and curing time was determined on the release of diclofenac from pellets coated with polymethacrylates. Increasing the plasticizer in the coating formula led to decrease in drug release and increasing the curing temperature and time resulted in higher drug release. The optimization process generated an optimum of 35% drug release at 3 hr. The level of plasticizer concentration, curing temperature and time were 20% w/w, 55 °C and 24 hr, respectively. This study showed that by controllinig the physical variables optimum drug release were obtained.

Novel application method of talcum powder to prevent sticking tendency and modify release of esomeprazole magnesium enteric-coated pellets

Actually, reflecting drug release from polymer-coated pellets remains a challenge. In this study, sticking of pellets caused by Eudragit®L30D-55 was observed during the release process, leading to change in drug release. Talcum powder (talc) was used in esomeprazole magnesium pellets to prevent sticking and modify release of pellets. Three methods including talc incorporated in enteric layer, physically mixed and coating resulted pellets were employed to prevent the sticking. The release of pellets was modified by addition talc into subcoat. The dispersion coefficient (Fd) and release profiles were determined in phosphate buffer solution (pH 6.8 and 6.0) and distilled water. It was found that the first manner made Fd increase to about 0.75, but the latter two methods could completely prevent sticking. Also, the second manner was more simple and readily scaled up. In addition, talc in subcoat significantly slowed the drug release in water, but the slowing release effect is less pronounced at pH 6.0 and 6.8. These different effects of talc were attributed to a different release mechanism in three media. The release profiles in water were fitted to Nuttanan model, and the K designated as “diffusive resistance constant” was linearly increased with talc levels in subcoat (R2 = 0.9874).