Carrier Ratio Research Articles

Development and characterization of tadalafil solid dispersion using skimmed milk for improved the solubility and dissolution release profile

Tadalafil has low solubility and low oral bioavailability, so it's a challenge to formulate suitable dosage form. In this Present investigation to enhance the dissolution rate and solubility skimmed milk is used as a carrier. Physical mixers were prepared using various drugs to carrier ratio. Material and Methods: Spry drying technology was used to prepared solid dispersion of drug with skimmed milk. Various techniques were used to characterize the solid dispersion immediately after they were made which includes Differential scanning calorimetry, fourier transform infrared spectroscopy, X-ray diffraction and in-vitro dissolution profiles. Results: The Differential Scanning Calorimetry thermograms of raw drug indicated of its anhydrous crystalline nature. In thermograms of solid dispersion, the characteristic peak was absent suggesting the change from crystalline nature to amorphous form. X-ray diffraction confirmed the results. The results of raw drug showed highly extreme peak characteristic of its crystalline nature where solid dispersion showed less intense, more diffused peak indicating the change in crystalline form. Fourier transform infrared spectroscopy studies indicated between drug and carrier there were no interaction. The whole formulation showed distinct enhancement in the drug release behavior and solubility. Conclusion: The optimum drug to carrier ratio 1:10 enhance the solubility and in-vitro drug release also increase by 3 fold. For improvement of drug release and solubility, it was concluded that as a carrier skimmed milk powder can be utilized very well.

Spray-dried liposomes: A study of the effect of carbohydrate carrier and concentrations on liposome size and drug entrapment

Background and objective: Dry powder inhalation provide many promising features for drug delivery to the pulmonary system, such as localization of drug within the lungs, drug retention in the respiratory tract, and reduced systemic toxicities. This study aimed to prepare dry powders of liposomes containing salbutamol sulfate using spray drying and study the influence of carrier type and concentration on liposome size and drug entrapment following rehydration of liposomal powder. Methods: Ethanol based proliposomes technique was used to generate liposomes containing salbutamol sulfate. Carbohydrate carriers: lactose, trehalose, sucrose, and mannitol in 1:6 or 1:10 (w/w) lipid to carrier ratio were separately incorporated into liposome formulations and dried by Buchi Mini-SprayDryerB-290. The protective effects of the sugars were investigated in terms of product yield (%), volume median diameter and size distribution of liposomes and entrapment efficiency of the drug. Results: The product yield (%) of spray dried liposome formulations with carriers was in the following order; trehalose (94.02 ± 1.20%) > sucrose (69.91 ± 1.75%) > lactose (68.30 ± 1.14%) > mannitol (50.16±0.80%) for the 1:6 formulations. Depending on the carrier type and lipidto carrier ratio, the vesicle size of liposomes with lactose and mannitol increased significantly (P 0.05) compared to the control formulations (3.6µm ±0.24). For 1:10formulation, the vesicle size with mannitol (P <0.001) and sucrose (P <0.001) increased significantly. The drug entrapment efficiency using the 1:6 formulations was 20.74±1.78% for sucrose, 35.59±2.42% for trehalose, 67.21±1.89 % for lactose, and 80.84±3.64% for mannitol. Conclusion: Stable spray-dried liposomes were manufactured using sugars as carriers. The findings of this study have demonstrated the potential using of carbohydrate carriers to increase the physical stability of liposomes during the drying process, and trehalose can offer formulations with most desirable characteristics, while mannitol showed the least benefits.

Paclitaxel-loaded micro or nano transfersome formulation into novel tablets for pulmonary drug delivery via nebulization.

A simplistic approach was adopted to manufacture novel paclitaxel (PTX) loaded protransfersome tablet formulations for pulmonary drug delivery. The large surface area offered by the pulmonary system acts as a desirable site for anti-cancer drug deposition; offering localized effect within the lungs. Protransfersomes are dry powder formulations, whereas transfersomes are liquid dispersions containing vesicles generated from protransfersomes upon hydration. Protransfersome powder formulations (F1-F27) (referred as Micro formulations based on transfersomes vesicles size post hydration) were prepared by employing a phospholipid (Soya phosphatidylcholine (SPC)), three different carbohydrate carriers (Lactose monohydrate, LMH; Microcrystalline cellulose, MCC; and Starch), three surfactants (i.e. Span 80, Span 20 and Tween 80) in three different lipid phase to carrier ratios (i.e. 1:05, 1:15 and 1:25 w/w), with the incorporation of PTX as a model drug. Hydrophobic chain of SPC may enhance PTX solubility, entrapment and targetted delivery via transfersome vesicles. Out of the 27 Micro protransfersome formulations, PTX-loaded LMH powder formulations F3, F6 and F9 (i.e. 1:25 w/w lipid phase to carrier ratio) exhibited excellent powder flowability via angle of repose (AOR) and good compressibility index due to associated smaller and uniform particle size and shape of LMH. Following hydration, these formulations also showed smaller volume median diameters (VMD) in micrometres (5.65±0.85-6.76±0.61µm) and PTX entrapment of 93-96%. Hydrated transfersome formulations (F3, F6 and F9) were converted into Nano size via probe sonication and referred to as Nano formulations. These Nano formulations were converted into dry powder via spray drying (SD) (F3NSD, F6NSD and F9NSD) or freeze drying (FD) (F3NFD, F6NFD and F9NFD). Post manufacture of protransfersome tablets (i.e. 9 formulations), quality control tests were conducted in accordance to British Pharmacopeia (BP). Only the Micro formulations protransfersome tablets (i.e. F3, F6 and F9) passed the uniformity of weight test, exhibited high crushing strength and tablet thickness when compared to SD or FD protransfersome tablets. Micro protransfersome formulations (i.e. F3, F6 and F9) into tablets demonstrated a shorter nebulization time and high output rate when using Ultrasonic nebulizer compared to Vibrating mesh nebulizer (i.e. Omron NE U22). Based on formulations, characterizations and nebulizer performance; Micro protransfersome tablet formulations F3, F6 and F9 (i.e. 1:25 w/w) and Ultrasonic nebulizer were found to be a superior combination, eliciting enhanced output efficiency. Moreover, PTX-loaded F3, F6 and F9 tablet formulations (10%) exhibited toxicity (60, 68 and 67% cell viability) to cancer MRC-5 SV2 (i.e. immortalized human lung cells) while safe to MRC-5 (normal lung fibroblast cells) cell lines.

Improving the Dissolution of Triclabendazole from Stable Crystalline Solid Dispersions Formulated for Oral Delivery.

Triclabendazole belongs to the class II/IV of the Biopharmaceuticals Classification System, and its low aqueous solubility represents a major drawback during the development of effective dosage forms. Therefore, the goal of this study was to elucidate whether polymeric solid dispersions would represent a suitable approach to overcome such disadvantage. Due to the lack of information on triclabendazole release, four different dissolution media were evaluated to analyze drug dissolution rate. The polymeric solid dispersions were characterized by X-ray diffraction and Fourier transform infrared spectroscopy. The selected final formulations were further stored for 24 months, and their physical stability was evaluated by means of X-ray diffraction and drug dissolution assays. Drug solubility studies indicated that poloxamer 407 (P407) solubilized a higher amount of drug than polyethylene glycol 6000. Drug-to-carrier ratio, nature of the selected carriers, and the type of dissolution media were important factors for increasing dissolution. By infrared spectroscopy, there were no specific interactions between the drug and polymers. The physicochemical characterization of the systems showed a detectable evidence of drug amorphization by increasing the carrier ratio. Micromeritic studies indicated that raw triclabendazole, physical mixtures, and reference formulation showed poor flow properties, in contrast to the triclabendazole:P407 solid dispersion sample. Both the crystalline properties and dissolution rate of selected samples were very similar after 24 months at room temperature. Thus, considering physical stability and dissolution studies, the development of the solid dispersion is a very suitable methodology to improve triclabendazole dissolution and, potentially, its biopharmaceutical performance.

Integrated thermodynamic analysis of electron bifurcating [FeFe]-hydrogenase to inform anaerobic metabolism and H2 production

Electron bifurcating, [FeFe]-hydrogenases are recently described members of the hydrogenase family and catalyze a combination of exergonic and endergonic electron exchanges between three carriers (2 ferredoxinred− + NAD(P)H + 3 H+ = 2 ferredoxinox + NAD(P)+ + 2 H2). A thermodynamic analysis of the bifurcating, [FeFe]-hydrogenase reaction, using electron path-independent variables, quantified potential biological roles of the reaction without requiring enzyme details. The bifurcating [FeFe]-hydrogenase reaction, like all bifurcating reactions, can be written as a sum of two non-bifurcating reactions. Therefore, the thermodynamic properties of the bifurcating reaction can never exceed the properties of the individual, non-bifurcating, reactions. The bifurcating [FeFe]-hydrogenase reaction has three competitive properties: 1) enabling NAD(P)H-driven proton reduction at pH2 higher than the concurrent operation of the two, non-bifurcating reactions, 2) oxidation of NAD(P)H and ferredoxin simultaneously in a 1:1 ratio, both are produced during typical glucose fermentations, and 3) enhanced energy conservation (~10 kJ mol−1 H2) relative to concurrent operation of the two, non-bifurcating reactions. Our analysis demonstrated ferredoxin E°′ largely determines the sensitivity of the bifurcating reaction to pH2, modulation of the reduced/oxidized electron carrier ratios contributed less to equilibria shifts. Hydrogenase thermodynamics data were integrated with typical and non-typical glycolysis pathways to evaluate achieving the ‘Thauer limit’ (4 H2 per glucose) as a function of temperature and pH2. For instance, the bifurcating [FeFe]-hydrogenase reaction permits the Thauer limit at 60 °C if pH 2 ≤ ~10 mbar. The results also predict Archaea, expressing a non-typical glycolysis pathway, would not benefit from a bifurcating [FeFe]-hydrogenase reaction; interestingly, no Archaea have been observed experimentally with a [FeFe]-hydrogenase enzyme.

Immobilization of β-galactosidase on tannic acid stabilized silver nanoparticles: A safer way towards its industrial application.

In this study, β-galactosidase has been immobilized on tannic acid stabilized silver nanoparticles (AgNPs). Tannic acid is a phytochemical and it is advantageous to use it as a linker molecule for immobilization because of its antidiarrheal and antimicrobial properties, and very low toxicity. AgNPs with immobilized β-galactosidase were characterized for particle size and catalytic properties. The AgNPs consisted of almost monodispersed particles of average diameter of ∼20 nm. β-galactosidase immobilized on tannic acid stabilized AgNPs (83.6% Immobilization yield) exhibited good activity with a high enzyme to carrier ratio as compared to the previous reports. Immobilization did not affect the optimum pH (pH 4.5) of the enzyme, however it retained greater fraction of activity in both alkaline and acidic pH range. The immobilized enzyme exhibited greater fraction of activity at higher temperatures as compared to the soluble enzyme, and its optimum temperature increased by 5 °C. The immobilized enzyme retained almost 60% of its activity after 10th successive use. The immobilized enzyme hydrolyzed 258 and 474 μM lactose from 1% lactose and from milk lactose, respectively, whereas the soluble enzyme hydrolyzed 235 and 424 μM lactose from 1% lactose and from milk lactose, respectively. Excellent activity and stability of β-galactosidase immobilized on AgNPs provides a cost-effective industrial application of this enzyme. β-galactosidase immobilized on tannic acid stabilized AgNPs are free from toxicity hazards of the linker molecules. Hence, it may find constructive enzyme based applications in food technology.

Development of an Oxcarbazepine Solid Dispersion Using Skimmed Milk to Improve the Solubility and Dissolution Profile

Oxcarbazepine has low solubility and low oral bioavailability, so it’s a challenge to formulate suitable dosage form. In this present investigation, to improve the dissolution rate and solubility, skimmed milk is used as a carrier. Physical mixers were prepared using various drugs to carrier ratio and spray drying technology was used to develop solid dispersion with the carrier. Various techniques were used to characterize the solid dispersion immediately after they were made which includes differential scanning calorimetry, scanning electron microscopy, fourier transform infra-red spectroscopy, X-ray diffraction and in-vitro dissolution profiles. The differential scanning calorimetry thermograms of raw drug indicated of its anhydrous crystalline nature. In thermograms of solid dispersion, the characteristic peak was absent suggesting the change from crystalline nature to amorphous form. X-ray diffraction confirmed those results. X-ray diffraction results of raw drug showed highly intense peak characteristic of its crystalline nature where solid dispersion showed less intense, more diffused peak indicating the change in crystalline form. Fourier transforms infra-red spectroscopy studies showed there was no interaction between drug and carrier. Scanning electron microscopy support the amorphous nature of mixer. The whole formulation showed distinct enhancement in the drug release behavior and solubility. The optimum oxcarbazepine to skimmed milk ratio 1:3 enhances the in-vitro drug release by 3.5 fold and also show distinct increase in solubility. It was concluded that for improvement of solubility of poorly water soluble oxcarbazepine, skimmed milk powder as a carrier can be utilize very well.

Floral Visitation Can Enhance Fitness of Helicoverpa armigera (Lepidoptera: Noctuidae) Long-Distance Migrants.

Numerous insect species engage in seasonal, trans-latitudinal migration, in response to varying resource availability, climatic conditions and associated opportunities, to maximize fitness and reproductive success. For certain species, the interaction between migrant adults and individual host plants is well-studied under laboratory conditions, but scant knowledge exists on the nutritional ecology of wild (i.e., field-caught) moths. During 2017-2018, we trapped adults of the cotton bollworm Helicoverpa armigera (Hübner) along its migration pathway in northeastern China and used pollen grain analysis to assess its visitation of particular host plants. Next, we assessed life history effects of adult feeding on carbohydrate-rich resources, for migrant individuals. Pollen grain analysis revealed H. armigera visitation of 32 species from 28 families, with the largest carrier ratio for northward migrants. Evening primrose (Oenothera spp.) accounted for 48% of pollen grains, indicating a marked H. armigera feeding preference. Furthermore, feeding on sugar-rich foods benefited adult fitness, enhanced fecundity by 65-82% and increased flight distance by 38-55% as compared to unfed individuals. Also, the degree of enhancement of reproduction and flight performance following sugar feeding varied between different migratory cohorts. Our work combines (polymerase chain reaction [PCR]-assisted) palynology and laboratory-based life history trials to generate novel perspectives on the nutritional ecology of long-distance migratory insects. These findings can aid the development of population monitoring and 'area-wide' management strategies for a globally-important agricultural pest.

Improvement of dissolution and tabletability of carbamazepine solid dispersions with high drug loading prepared by hot-melt extrusion.

Solid dispersions (SDs) have made great progress in the improvement of dissolution for poorly soluble drugs, however the low drug loading still limits their wide application. In the present paper, high carbamazepine (CBZ) loaded SDs with excellent dissolution and tabletability were prepared and characterized. The CBZ SDs were prepared with Eudragit EPO as carrier by hot-melt extrusion (HME) in the drug: carrier ratio of 4:1. Powder X-ray diffraction, differential scanning calorimetry, fourier transform infrared spectroscopy and powder dissolution was carried out to characterize the SDs. The results showed that the crystalline form the polymorph of CBZ in SDs was transformed into form I from form III after extruded at 140 °C. Wettability and microstructure of CBZ SDs were improved by the HME process, which promoted the dissolution significantly. More than 85 % drug dissolved within 5 min from CBZ SDs with even only 20 % Eudragit EPO as carrier. CBZ SDs tablets were prepared by direct tableting with a universal material testing machine at various compaction pressures. Compactibility and tabletability were enhanced significantly by the HME process. All of these results showed the CBZ SDs prepared by HME with 80 % CBZ and 20 % Eudragit EPO could improve the dissolution and tabletability significantly.

Fast Sensor-Less Voltage Balancing and Capacitor Size Reduction in PUC5 Converter Using Novel Modulation Method

This paper proposes a novel sensor-less switching method based on logic gates for a five-level packed U-cell (PUC5) converter. It comprises only two level-shifted triangular carriers and logic gates. Hence, the number of triangular carriers is halved and the switching states table is eliminated, which cause remarkable reduction in complexity of the proposed modulation method. Moreover, employing the proposed sensor-less switching method leads to decrease in the PUC5 capacitor value by a factor of carrier ratio, fast self-balancing of the PUC5 capacitor voltage, and halving the output LC filter inductor and capacitor values in stand-alone mode, as well as the grid-link inductor value in grid-connected mode. In addition, the PUC5 converter start-up transient time is considerably decreased and the first switching harmonic cluster frequency is doubled, which lead to notable improvement of steady-state and dynamic performances of the PUC5 converter. The proposed sensor-less switching method has been implemented in both stand-alone and grid-connected operating modes of PUC5 converter. Provided simulation and experimental results verify the feasibility and effectiveness of the proposed sensor-less switching method as well as its improved dynamic and steady-state performances in both stand-alone and grid-connected modes.

Comparative Study on Single Pulse and Dual Pulses Variable Width Control Strategies for High-Speed PM BLDC Motor Drive

Pulse width modulation (PWM) of voltage source inverter (VSI) is common for speed regulation of permanent magnet (PM) brushless direct-current (BLDC) motor drives. However, when the motor runs at high speed, the conventional PWM technique may become unfeasible due to the low carrier ratio of inverter, which makes the motor current distorted and the motor core loss increased significantly. In this paper, two control strategies, namely single pulse variable width (SPVW) and dual pulses variable width (DPVW), are introduced for the high-speed PM BLDC motor drives, and are comprehensively investigated. Finite element method (FEM) is employed to evaluate and compare the drive system performance when using the conventional PWM, and the proposed SPVW and DPVW, respectively. Influence of the control techniques, especially on the loss distribution, is revealed.

Encapsulation of non-dewaxed propolis by freeze-drying and spray-drying using gum Arabic, maltodextrin and inulin as coating materials

The aim was to obtain alcohol-free, water-dispersible propolis powder from non-dewaxed propolis extract, with high levels of phenols, with either freeze-drying or spray-drying. Optimisation was performed with different wall materials, centrifugation settings and propolis:carrier ratios, and was carried out by monitoring the effect of one parameter at a time on the dependable variables. The powders obtained contained high phenol levels, which included known bioactive components, and also showed high dispersibility in cold water and high antioxidant activity. Furthermore, the propolis powders were stable in water for up to 24h, and the release of encapsulated phenols did not change across different environmental values, as pH 3–6. Differential scanning calorimetry showed that propolis interacts with and stabilises the carrier material (gum Arabic), also high pressure liquid chromatography showed that the profiles of the powders remained unchanged across all encapsulation techniques. This study demonstrates that the same propolis formulations can be fine-tuned to suit specific final applications and confirms that freeze-drying is a viable alternative to the more established spray-drying for encapsulation of propolis. This study also demonstrates that non-dewaxed propolis extract is a better alternative for encapsulation purposes, as no phenolic compounds are lost during its processing.

Quasi-Proportional-Resonant Controller Based Adaptive Position Observer for Sensorless Control of PMSM Drives Under Low Carrier Ratio

The position and speed estimation performance of the sliding mode observer (SMO) for permanent magnet synchronous motor (PMSM) drives under low carrier ratio degrades, due to the inherent chattering and enlarged control delay. To improve estimation performance, this paper proposes a quasi-proportional-resonant (QPR) based adaptive observer to obtain back electromotive force with adaptive harmonics cancellation. In this observer, the QPR controller is employed to eliminate errors between the observed currents and the actual ones in the αβ reference frame, replacing sign function and low pass filter (LPF) of the SMO to cancel the chattering, and harmonics immune performance can also be achieved thanks to frequency selection characteristic of the QPR controller. Besides cancelling the chattering, the proposed observer can also eliminate phase shift produced by the LPF, since the QPR controller is a zero phase-shift amplifier at the resonant frequency. Comparative experiments are carried out in a 3-kW PMSM drive, and the results validate the effectiveness of the proposed adaptive position observer.

Pharmacokinetic enhancement of poorly aqueous soluble rosuvastatin using natural gum as carriers: pharmaceutical modeling of release kinetics and bio-stastistical evaluation

The major focus of the present investigation is to enhance the solubility and dissolution rate of Rosuvastatin Calcium. Preaparation of Solid dispersions of Rosuvastatin Calcium by using Vitamin E TPGS, A.Marmelos, and Gum Karaya as carriers in different ratios through solvent evaporation method. As Solid dispersions have been traditionally used effective techniques to improve the dissolution properties and bioavailability of poorly-soluble drugs. The model drug selected Rosuvastatin Calcium, which is BCS class-II drug with anti-hyperlipidemic potential. The reported bioavailability from oral route of drug is only 20%. So aim of current study is to improve the solubility and dissolution rate of a poorly water-soluble drug Rosuvastatin Calcium, by solid dispersion technique. Physical mixtures and solid dispersions were prepared using Vitamin E TPGS, MGK & natural polymers A.Marmelos in different to drug to carrier ratios, dispersions were prepared by solvent evaporation technique. Prepared formulations were characterized in solid state by FTIR analysis, powder X-ray diffraction, Scanning electron microscopy and in-vitro dissolution study. The aqueous solubility of Rosuvastatin Calcium was favored by presence of both the polymers. Solid state characterizations indicated the Rosuvastatin Calcium was present in amorphous form and entrapped in polymer matrix. In contrast to the very slow dissolution rate of pure Rosuvastatin Calcium, the dispersion of the drug in the polymers considerably enhanced the dissolution rate. Solid dispersion prepared with TPGS showed maximum 91.19% Drug release. The best formulation of solid dispersion selected and subjected to fast dissolving tablets. The mixtures of solid dispersion and excipients were evaluated for pre-compression parameters. After then fast dissolving tablets were prepared by direct compression technique. The formulated tablets were evaluated by post compression parameters. In-vitro drug release performance of the develope

Optimization of a dry powder inhaler of ciprofloxacin-loaded polymeric nanomicelles by spray drying process

Ciprofloxacin is a commonly prescribed antibiotic for treatment of pulmonary infections. Nanocarriers such as nanomicelles can increase the drug residence time in the lungs and enhance their antibacterial effects. Dry powder inhalers (DPIs) are the preferred pulmonary drug delivery system and preparation of an optimum nanoaggregate from nanomicelles by means of spray drying would be valuable. The two-level full factorial design was performed in 16 runs. The effects of carrier type, anti-adhesion agent type, carrier to nanoparticle ratio and anti-adhesion agent to carrier ratio on the size of the microparticles, their in vitro pulmonary deposition, and redispersibility were investigated. Its antibacterial effects against Pseudomonas aeruginosa, Klebsiella pneumoniae, and Streptococcus pneumoniae also were investigated. All independent variables were fitted into two-factorial interaction models. The optimum nanoaggregate was prepared using mannitol and L-phenylalanine with a D0.5 of 1.7 µm and 60% fine particles. The process had no negative effect on the stability or drug release profile of the nanomicelles. The antibacterial effects of ciprofloxacin against microorganisms increased significantly. This spray drying process could be used for preparation of an optimum DPI from polymeric nanomicelles. This formulation could increase the efficacy of ciprofloxacin for treatment of pulmonary infections.

Preparation, characterization and ex vivo–in vivo assessment of candesartan cilexetil nanocrystals via solid dispersion technique using an alkaline esterase activator carrier

The objective of this study was to improve candesartan cilexetil (CC) efficacy by formulating nanocrystals via solid dispersion (SD) technique using tromethamine (Tris). SD was prepared by solvent evaporation at different drug carrier ratios, evaluated for particle size, vitro dissolution studies, TEM, FTIR, and X-ray powder diffraction. Ex vivo, in vivo pharmacokinetic parameters were conducted on selected formulae compared to drug suspension and marketed product. Size analysis demonstrated formation of particles in the nanorange lower than 300 nm. A burst drug release followed by an improved dissolution was observed indicating instant formation of nanocrystals along with amorphization as confirmed by X-ray diffraction. FTIR studies suggested the absence of chemical interaction between Tris and CC. TEM revealed formation of irregular oval nanoparticles. SD-1:5 has higher apparent permeability coefficient compared to CC suspension. Furthermore, the pharmacokinetic results proved the ability of the formed nanoparticles to enhance the efficacy of CC compared to drug suspension and marketed product. In conclusion, using of Tris as alkaline esterase activator carrier could be a promising tool to bypass the controversial effect of esterase enzymes that may be a source for inter-individual variations affecting ester prodrug candidates’ efficacy.

Formulation of Gastro-retentive Floating Tablets of Valsartan by 2 power 2 Factorial Designs: In vitro and In vivo Evaluations

An oral dosage form containing gastro-retentive floating tablets forms a stomach-specific drug delivery system for the treatment of hypertension. Valsartan belongs to the BCS class II (poo Classification System). It is desirable to improve the extent of bioavailability (23%). The objective of the present study was to apply design of experiment to optimize floating drug delivery of valsartan by employing 22 factorial design. Improvement of the aqueous solubility of valsartan was done by solid dispersions using hot melt extrusion technique. Plasdone S630 copovidone is a variable carrier and drug to carrier ratio of 1:2 was optimized. Valsartan floating tablets were prepared by employing factorial design (22), where HPMC K15M (X1) and pregelatinized starch (X2) were independent variables and drug dissolution was the dependent parameter (Y1) to prepare matrix tablets. The factorial analysis, steepest ascent method was utilized for obtaining optimized formulation. In vitro evaluation, In vivo radiographic study and biopharmaceutical analysis in rabbits for valsartan optimized formulation (FT-5). Floating lag time (FLT) for valsartan optimized formulation (FT-5) was 15 s and total floating time (TFT) of the tablets was about 33 h, which was satisfactory. A four-point (1 h, 4 h, 8 h and 16 h) dissolution analysis gave satisfactory dissolution profile up to 24 h. The release kinetics of valsartan optimized formulation (FT-5) followed zero order and the release mechanism was found to be Korsemeyer Peppas model, i.e. swelling type. The dissolution efficiency for valsartan floating tablets was 1190.89% against the marketed formulation of 39.77%. The accelerated stability profile of valsartan optimized formulation (FT-5) was evaluated in terms of drug content and percent cumulative dissolution of valsartan in 24 h, in a 6 months study. In vivo X-ray image study for valsartan optimized formulation (FT-5) indicated the presence of intact tablet up to 12 h in gastric region of rabbit. The biopharmaceutical analysis in rabbits was conducted for valsartan optimized formulation (FT-5). The HPLC method was established and validated for the in vivo analysis. The Cmax was 453.2 ng/mL compared to that of the marketed tablets (522.4 ng/mL). The mean residence time (MRT) for the valsartan optimized formulation (FT-5) was 14.82 h as against 4 h for marketed tablet. The relative bioavailability of valsartan optimized formulation (FT-5) was 650% higher than the marketed tablet. To overcome the poor bioavailability of valsartan, it was suitably modified using hot-melt extrusion for improving therapeutic outcome. In conclusion, gastro-retentive drug delivery system is an excellent approach for improving the bioavailability of valsartan. &#x0D;

Formulation, Characterization and Solubility Enhancement of Manidipine Solid Dispersions

The study was aimed to formulate solid dispersions of Manidipine by using different novel carriers like Labrafac PG, Kolliwax RH 40, Soluplus, Kolliwax GMS II, Kolliphor EL and SLS in drug carrier ratio by using solvent evaporation method. The formulations were characterized for physical appearance, solubility and in vitro dissolution studies. The optimized formulation was characterized and Formulation SD13 was found to be optimized one based on the solubility, dissolution and other parameters using Kolliwax GMS II and SLS. The drug release of the optimized formulation was found to be 99.41±5.38% within 90 min. Powder X-ray diffraction studies performed on solid dispersion showed that Manidipine existed in the amorphous form within the solid dispersion formulation fabricated using the solvent evaporation process. Additionally, scanning electron microscopy studies suggested the conversion of crystalline Manidipine to an amorphous form. Therefore, the solid dispersions using Kolliwax GMS II as hydrophilic carrier in the combination of SLS can be successfully used for improvement of solubility and dissolution of Manidipine.

Influence of spray drying encapsulation on the retention of antioxidant properties and microstructure of flaxseed protein hydrolysates.

In this research, bioactive peptides produced from flaxseed protein by alcalase, pancreatin, trypsin and pepsin, were encapsulated by spray drying. After analysis of amino acid composition and antioxidant properties of hydrolysates, the effect of spray-drying encapsulation via different maltodextrin (MD) to hydrolysate ratios (1:1, 2:1 and 3:1 w/w) on the production yield, physicochemical properties, functional activities, chemical structure, and morphology of final powder particles were evaluated. Among the hydrolysates, peptides produced with alcalase had the highest hydrolysis degree (38.2%), hydrophobic amino acids (255 mg/g) and antioxidants (126 mg/g). Among spray-dried samples, the powders obtained by 3:1 w/w ratio (MD: peptide) showed the highest radical scavenging activity for DPPH- (68.93%), ABTS+ (85.62%), hydroxyl (94.97%), nitric oxide (64.03%), reducing power (95.49%), total antioxidant activity (96.68%), and iron (95.31%) and copper (95.49%) chelating activity. Evaluation of chemical structure (FTIR) indicated that hydrolysates were coated and dispersed within maltodextrin matrix. SEM images showed the effect of different carrier ratios on the production of irregular and shrunk particles with different sizes and matrix-type structures.

Synthesis gas production from chemical looping gasification of lignite by using hematite as oxygen carrier

Chemical looping gasification (CLG) of lignite by using hematite oxygen carrier is performed to achieve high purity synthesis gas. The oxygen carrier reaction performance as well as the effects of temperature and lignite/oxygen carrier ratio on the syngas evaluation are investigated by TG and fixed bed reactor coupling with various analytical methods. The experimental results reveal that the hematite oxygen carrier consisting primarily of Fe2O3, SiO2 and Al2O3 presents three H2 reduced peaks at 472.59 °C, 634.17 °C and 849.01 °C respectively, corresponding to the crystal form transition from Fe2O3 to Fe. Lignite pyrolyzes preferentially to generate intermediates then further reacts with oxygen carrier to produce synthesis gas in CLG process, following the oxygen carrier reaction path of Fe2O3 → Fe0.963O → Fe2O3. Oxygen carrier plays a key role in promoting lignite conversion to synthesis gas in CLG process owing to the lattice oxygen shifting reactions equilibrium to the direction of syngas production. Excessive lattice oxygen is beneficial to CLG reaction until the L/O ratio reaches to 4/6 with the limitation of heat and mass transfer in reaction system. However, the minimum value of O/L is 2/8, which ensures the oxygen carrier makes obvious promotion effect in reaction process. High temperature improves synthesis gas yield and carbon conversion by enhancing endothermic reactions in CLG process. The hematite oxygen carrier recovers main crystalline phase after the CLG process without serious sintering.