pH Dissolution Research Articles

Combined Atomistic Molecular Calculations and Experimental Investigations for the Architecture, Screening, Optimization, and Characterization of Pyrazinamide Containing Oral Film Formulations for Tuberculosis Management.

To date, effective treatment, prophylaxis, and control of tuberculosis (TB) infection is mainly dependent on the use of drugs. However, patient noncompliance with prescribed anti-TB treatment schemes remains a major problem confronting successful pharmacotherapeutic outcomes. Thus, the development of alternative delivery systems that can improve adherence for the existing anti-TB bioactives has been intensified in recent times. The aim of this investigation was to engineer an optimal, thermodynamically stable oral film (OF) formulation containing a key anti-TB agent, pyrazinamide (PYZ), employing molecular modeling and experimental tools. Four PYZ-loaded film variants (OF 1, OF 2, OF 3, OF 4) were constructed in silico and then prepared in vitro using the Accelrys Materials Studio software and solvent casting method, respectively. Screening and selection of the optimal OF was based on the computation of the total interaction energy (ET), kinetic energy (EK), solubility parameter (S), and cohesive energy density (CED) as well as determining mass, thickness, dissolution and disintegration times, dissolution pH, drug loading capacity, and surface morphology in vitro. OF 2 was selected as the optimal formulation as it displayed the lowest ET (-8006.28 kcal/mol), dissolution time (9.96 min), disintegration time (56.49 s), and weight (39.33 mg); moderate EK (1052.98 kcal/mol); highest S (44.55 (J/cm(3))(0.5)) and CED (1.99 × 10(9) J/m(3)), slim dimension (166 μm), good and unvarying drug loading capacity (98.04%), acceptable dissolution pH (6.70), and well-layered surface topography. The drug release behavior of the optimal OF 2 was best elucidated with the zero order (R(2) = 0.97) and Korsmeyer-Peppas (R(2) = 0.99) models. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and differential scanning calorimetry (DSC) analyses showed that OF 2 was made of physically mixed multiple component polymeric and nonpolymeric compounds. OF 2 was semicrystalline in nature and displayed a dual phased ex vivo mucosal permeation pattern. In silico and in vitro physicomechanical quantities revealed OF 2's flexibility, robustness, and compressibility. OF 2 was most stable under controlled environmental humidity, pressure, and temperature conditions in silico and in vitro. OF 2 was potentially non-cytotoxic and biocompatible. Succinctly, this work demonstrated the applicability of a combination of atomistic molecular mechanics and dynamics calculations as well as experimental analyses to the fabrication, screening, optimization, and characterization of drug formulations. Lastly, the fabricated OF 2 formulation can function as a potential alternative for the effective loading and delivery of PYZ.

Pectin/anhydrous dibasic calcium phosphate matrix tablets for in vitro controlled release of water-soluble drug

Different pectin/anhydrous dibasic calcium phosphate (ADCP) matrix tablets have been developed in order to obtain controlled release of a water-soluble drug (theophylline). Swelling, buoyancy and dissolution studies have been carried out in different aqueous media (demineralized water, progressive pH medium, simulated gastric fluid, simulated intestinal fluid and simulated colonic fluid), to characterize the matrix tablets. When the pectin/ADCP ratio was ≥0.26 (P1, P2, P3 and P4 tablets) a continuous swelling and low theophylline dissolution rate from the matrices were observed. So, pectin gel forming feature predominated over the ADCP properties, yielding pH-independent drug release behavior from these matrices. On the contrary, pectin/ADCP ratios ≤0.11 (P5 and P6 tablets) allowed to achieve drug dissolution pH dependent. Consequently, the suitable selection of the pectin/ADCP ratio will allow to tailor matrix tablets for controlled release of water-soluble drugs in a specific manner in the gastrointestinal tract.

Fluoride estimation and its correlation with other physicochemical parameters in drinking water of some areas of Balochistan, Pakistan.

The fluoride level in drinking water is an important parameter and has to be controlled in order to prevent dental and skeletal fluorosis. The objective of this study is to assess fluoride content and other water quality parameters in the samples taken from open wells, tube wells, and karezes of Mastung, Mangochar, and Pringabad areas of Balochistan province. A total number of 96 drinking water samples out of 150 were found unfit for human consumption. Area-wise analysis show that the samples from 39 sites from Mastung, 12 from Mangochar, and 13 from Pringabad were found in the risk of dental fluorosis of mild to severe nature. However, 12 sampling sites from Mastung, 8 from Mangochar, and 2 from Pringabad were identified as the risks of mottling and skeletal fluorosis or other bone abnormalities. The highest concentration of F(-) has been observed as 14 mg L(-1) in Mastung. Correlation analysis show that fluoride solubility in drinking water is pH dependent; and the salts of Ca(2+), Na(+), K(+), Cl(-), and SO4(2-) contribute to attain the favorable pH for dissolution of fluoride compounds in drinking water. Principal component analysis shows that the geochemical composition of the rocks is only responsible for groundwater contamination. On the basis of the results, defloridation of the identified sampling sites and continuous monitoring of drinking water at regular basis is recommended at government level to avoid further fluorosis risks.

Formulation Development and Optimization of Febuxostat Tablets by Direct Compression Method

ABSTRACTThe aim of this study was to develop a simple and cost‐effective Febuxostat film coated tablet formulation by the direct compression method. To obtain the best optimized product, nine different formulations were developed using a central composite rotatable design. Avicel PH‐102, Magnesium stearate, and croscarmellose sodium were taken as independent variables. Micromeritic properties of powder blend showed excellent flow properties and were within USP limits. Tablets were compressed and before coating the core was tested for weight variations, hardness, thickness, friability disintegration, and dissolution. Tablets were film coated using hydroxypropyl methylcellulose 5cps, titanium dioxide, polyethylene glycol, and Instacoat blue, and again tested for the weight variations, assay, and single point dissolution. Three different dissolution media, i.e., 0.1 N HCl (pH 1.2) and phosphate buffer pH 4.5 and 6.8, were used for calculating the percentage release of Febuxostat and their release pattern was compared with an innovator brand by using the model‐independent methods such as similarity (f2), dissimilarity (f1), and model‐dependent methods such as first‐order, Hixson Crowell, and Weibull methods. The results revealed that Trial‐06 showed the maximum similarity, i.e., 81.18, 75.15, and 67.19 in three different pH dissolution media. Dissimilarity factor was also comparable in Trial 06, i.e., 5.21, 11.27, and 6.01 at pH 1.2, 4.5, and 6.8, respectively. Model‐dependent approaches showed the maximum r2 values for Trial 06, i.e., greater than 0.900 for all models in the above‐mentioned pH, whereas the overall release kinetics followed the Weibull model. Selected formulation was kept at 40 ± 5°C and 75 ± 2% relative humidity for accelerated stability studies, and no specific change was observed.

In vitro dissolution of proton-pump inhibitor products intended for paediatric and geriatric use in physiological bicarbonate buffer

Proton-pump inhibitor (PPI) products based on enteric coated multiparticulates are design to meet the needs of patients who cannot swallow tablets such as children and older adults. Enteric coated PPI preparations exhibit delays in in vivo absorption and onset of antisecretory effects, which is not reflected by the rapid in vitro dissolution in compendial pH 6.8 phosphate buffer commonly used for assessment of these products. A more representative and physiological medium, pH 6.8 mHanks bicarbonate buffer, was used in this study to evaluate the in vitro dissolution of enteric coated multiparticulate-based PPI products. Commercially available omeprazole, lansoprazole and esomeprazole products were subject to dissolution tests using USP-II apparatus in pH 4.5 phosphate buffer saline for 45min (acid stage) followed by pH 6.8 phosphate buffer or pH 6.8 mHanks bicarbonate buffer. In pH 6.8 phosphate buffer, all nine tested products displayed rapid and comparable dissolution profiles meeting the pharmacopeia requirements for delayed release preparations. In pH 6.8 mHanks buffer, drug release was delayed and failed the pharmacopeia requirements from most enteric coated preparations. Despite that the same enteric polymer, methacrylic acid–ethyl acrylate copolymer (1:1), was applied to all commercial multiparticulate-based products, marked differences were observed between dissolution profiles of these preparations. The use of pH 6.8 physiological bicarbonate (mHanks) buffer can serve as a useful tool to provide realistic and discriminative in vitro release assessment of enteric coated PPI preparations and to assist rational formulation development of these products.

Characterization of Myofibrillar Chicken Breast Proteins for Obtain Protein Films and Biodegradable Coatings Generation

Abstract The present work contains studys of extraction and characterization of myofibrillar proteins from chicken breast meat. There were used several methods of extraction of myofibrillar proteins and the protein concentrat myofibrillar was analysed physico-chemical. The current study refers to myofibrillar protein extraction and their characterization, from chicken breast meat. Acid pH dissolution, followed by precipitation at isoelectric pH was used as extraction method. The myofibrillar protein chemical characterization was made by taking into account the functional and rheological properties. Also we study functional properties of concentrate myofibrillar proteins: solubility.,foam capacity and emulsion capacity The results showed that the best method for extraction and characterization of chicken breast myofibrillar proteins is the alkaline pH method. The protein concentrates/isolates, studied by their functional properties, protein solubility and gelling characteristics, can be suitable raw materials for protein films and biodegradable coatings generation

"MONOSPECIFIC" AND NEAR-MONOSPECIFIC BENTHIC FORAMINIFERAL FAUNAS, NEW ZEALAND

Research Article| July 01, 2014 “MONOSPECIFIC” AND NEAR-MONOSPECIFIC BENTHIC FORAMINIFERAL FAUNAS, NEW ZEALAND Bruce W. Hayward Bruce W. Hayward Geomarine Research, 49 Swainston Rd, St Johns, Auckland, New Zealand, e-mail: b.hayward@geomarine.org.nz Search for other works by this author on: GSW Google Scholar Journal of Foraminiferal Research (2014) 44 (3): 300–315. https://doi.org/10.2113/gsjfr.44.3.300 Article history received: 15 Jul 2013 accepted: 23 Mar 2014 first online: 03 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Bruce W. Hayward; “MONOSPECIFIC” AND NEAR-MONOSPECIFIC BENTHIC FORAMINIFERAL FAUNAS, NEW ZEALAND. Journal of Foraminiferal Research 2014;; 44 (3): 300–315. doi: https://doi.org/10.2113/gsjfr.44.3.300 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyJournal of Foraminiferal Research Search Advanced Search Abstract Thirteen benthic foraminiferal species dominate modern “monospecific” faunas (dead faunas with >80% of one species in >63-μm samples) in New Zealand. These faunas occur in sheltered, often brackish, intertidal or shallow-subtidal environments, never deeper than 25 m. None occurs along exposed coasts or in the open ocean. Seven agglutinated species (Entzia macrescens, Haplophragmoides wilberti, H. manilaensis, Miliammina fusca, M. obliqua, Trochammina inflata, Trochamminita salsa) dominate “monospecific” faunas in salt marshes with varying salinity and elevational ranges. All but H. manilaensis have been recorded comprising 99–100% of at least one fauna. A further six species (Ammobaculites exiguus, Ammonia aoteana, Ammotium fragile, Elphidium excavatum clavatum, E. williamsoni, E. gunteri) dominate “monospecific” faunas in unvegetated intertidal and shallow-subtidal (<3 m), sheltered estuary, inlet, or lagoon settings. “Monospecific” Amb. exiguus faunas are inferred to have been produced by dissolution of calcareous components. A further 17 species dominate modern near-monospecific faunas (50–80% of one species), 11 at depths <50 m and six in the open ocean at 50–4000-m depth. “Monospecific” and near-monospecific faunas are more common in higher latitudes, where overall species diversity is lower.Six species dominate “monospecific” early Miocene faunas in northern New Zealand: Elphidium crispum in a sheltered gravel beach; Nonionella novozealandica in a deep-water (50–100 m), possibly dysoxic harbour; and three larger, more robust species (Amphistegina aucklandica, Lepidocyclina orakiensis, Miogypsina intermedia) in current- or wave-concentrated beach or shallow-marine deposits. The only bathyal or abyssal “monospecific” fauna is dominated by Amphimorphinella butonensis occurring in a fossil hydrocarbon seep setting.Many of the modern “monospecific” faunas (especially those in salt marshes) are cosmopolitan, whilst most of the fossil and some of the modern faunas are endemic to the New Zealand region. These high-dominance faunas are produced by taphonomic and ecological processes. Taphonomic causes include wave or current concentration by winnowing or transport in high energy, shallow-marine environments and carbonate dissolution in low pH, brackish, salt marsh or deep-sea settings. Ecological drivers include highly specific adaptations that allow species to outcompete all others in stressful (intertidal), strongly variable (high-tidal brackish), or unusual (hydrocarbon seep) environments. Sometimes high test productivity of opportunistic species may result in near-monospecific faunas. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

PERBANDINGAN DISOLUSI ASAM MEFENAMAT DALAM SISTEM DISPERSI PADAT DENGAN PEG 6000 DAN PVP

ABSTRACT Mefenamic acid is an analgetic that insoluble in water, therefore several approaches are required to improve the dissolution and bioavailability. The aim of this research is to know the dissolution of mefenamic acid in solid dispersion system with PEG 6000 and PVP. Solid dispersion of mefenamic acid-PEG 6000 were prepared by fusion method and mefenamic acid-PVP by solvent evaporation method with contain PEG 6000 or PVP for FI (20%), FII (40%), FIII(60%), FIV (80%) and FV (100%) respectively were compared with the weight of mefenamic acid. The powder of solid dispersion systems were investigated for its recovery and dissolution in medium fosfat buffer pH 7.4 until 60 minutes. Pure mefenamic acid and the physical mixture with polimer were used as compared powders. The result of dissolution testing were revealed by Dissolution Efficiency (DE 60 ). The result showed that both PEG 6000 and PVP can increased the dissolution of mefenamic acid from solid dispersion systems. The DE 60 of mefenamic acid-PEG 6000 from FI 38,81%; FII 51,05%; FIII 62,87%; FIV 75,63%; FV 87,03%; and the physical mixture of FV 58,84% respectively. Meanwhile the DE 60 mefenamic acid-PVP from FI 26,76%; FII 37,78%; FIII 45,23%; FIV 62,41%; FV 82,71%; and the physical mixture of FV 26,44% respectively. Keywords : mefenamic acid, PEG 6000, PVP, solid dispersion, dissolution

Sildenafil vaginal suppositories: preparation, characterization, in vitro and in vivo evaluation

Aim: The main objective was to investigate the in vitro release profile/kinetics, and in vivo plasma pharmacokinetics (PK) and organ biodistribution (BD) of the prepared sildenafil vaginal suppositories (SVS).Methods: Suppositories containing 25 mg of sildenafil were prepared by the cream melting technique using Witepsol H-15 as a suppository base. The suppositories were characterized for weight variation, content uniformity, hardness, disintegration time and crystallinity change. The in vitro dissolution in pH 4.5, and in vivo plasma PK and organ BD of sildenafil from SVS in female Sprague Dawley rats, were also investigated.Results: The mean weight variation, content uniformity, hardness and disintegration time of the prepared SVS were 1.127 ± 0.020 g, 98.25 ± 2.50%, 2.5 ± 0.08 kg and 9 ± 1.0 min, respectively. The release of sildenafil from the SVS was more than 90% at 30 min, with a release kinetic of Hixson--Crowell model and non-Fickian diffusion (n = 0.464). The plasma PK study demonstrated a significantly lower Cmax (∼10 times) and AUC0–24 h (∼13 times) of sildenafil in plasma following intravaginal (IVG) administration of suppositories compared to oral (PO) administration of sildenafil solution. Nevertheless, the organ BD study showed a phenomenally higher Cmax (∼40 times) and AUC0–24 h (∼20 times) of sildenafil in uterus following IVG administration of suppositories than PO administration of sildenafil solution.Conclusion: This study demonstrated enhanced sildenafil exposure in the uterus following IVG administration of SVS, which could be used to target the uterus for therapeutic benefits.

Preparation and Characterization of Regenerated Wool Protein PAN Blended Fibers

Wasted wool fibers were dissolved by reductive method. The dissolved wool protein was extracted by the membrane technology and blended with the Polyacrylonitrile (PAN) polymer to prepare regenerated fiber. Effects of pH value and dissolution assisting agent type on dissolution percentage of the wasted wool fibers in sodium pyrosulfite reductive system were investigated. Effects of the drawing times on properties of the fibers were also studied. Results indicated that the dissolution percentage rose with the increase of pH value of the reductive solution. Metallic salts have better dissolution assisting effect than urea. Breakage percentage of the as-spun fiber and tenacity of the regenerated protein fiber rose with the increase of the drawing times.

Synthesis of Ni and Pt nanomaterials by cathodic contact glow discharge electrolysis in acidic and alkaline media

Ni, NiO, β-Ni(OH)2 and Pt nanomaterials are prepared with cathodic contact glow discharge electrolysis (CGDE) in acidic and alkaline media by alternating the Ni and Pt cathode vs. a large Ni anode. The morphological and crystalline characterizations of the products suggest two reaction mechanisms where in the first, metal ions are locally reduced by the high reducing agents generated by the electrical discharges from the cathode, i.e. the solvated electron, the H radical and secondary species if any. This is supported by CGDE experiments conducted in acidic environment with Ni or Pt cathode that gave Ni-based materials only. The second mechanism for the formation of metals aggregates is due to the cathode material electro-erosion due to the high temperature spots at its surface that lead to the local vaporization of its material and the rapid quenching of the generated powder. This conclusion is drawn after eliminating the source of Ni2+ ions, initially due to the Ni anode dissolution in acidic pH, and conducting the same two previous experiments in concentrated KOH solutions instead. In both arrangements, it is the cathode material that was the source of the synthesized nanoparticles.

Characterisation, dissolution and solubility of synthetic erythrite [Co3(AsO4)2.8H2O] and annabergite [Ni3(AsO4)2.8H2O] at 25°C

Dissolution of the synthetic erythrite [Co3(AsO4)2.8H2O] and annabergite [Ni3(AsO4)2.8H2O] was studied at 25°C and different pH values in a series of batch experiments. The X-ray diffraction, Fourier transformed infrared spectrophotometer and scanning electron microscopy analyses indicated that the synthetic erythrite and annabergite used in the experiments were found to have no obvious variation after 2880 h of dissolution. The releases of cobalt, nickel and arsenate into pH 2 solution were significantly higher than that into solution with initial pH 6 or 9. The release of cobalt and nickel into the bulk solution was always less when compared with release of arsenate. Within the first 24–48 h of dissolution, the solution pH increased rapidly and then decreased slightly until it approached a steady state. During the dissolution in pH 2 solution, the aqueous Co, Ni and As concentrations increased rapidly in the first hour and then decreased after 72–120 h. After that time they increased gradually once again and finally approached a steady state. The mean Ksp values were calculated by using PHREEQC for erythrite of 10−34·02 (10−33·53–10−34·68) at 25°C and for annabergite of 10−30·77 (10−29·83–10−32·57) at 25°C, the Gibbs free energies of formation and were calculated to be −3551·62 and −3506·68 kJ mol−1 respectively.On a étudié la dissolution de l’érythrite [Co3(AsO4)2.8H2O] et de l’annabergite [Ni3(AsO4)2.8H2O] synthétiques à 25°C et à différentes valeurs de pH dans une série d’expériences en discontinu. Les analyses de XRD, de FTIR et de SEM ont indiqué que l’érythrite et l’annabergite synthétiques utilisées dans les expériences n’avaient pas de variation apparente après 2880 h de dissolution. Les relâchements de cobalt, de nickel et d’arséniate dans la solution à pH 2 étaient significativement plus élevés que ceux de la solution à pH initial de 6 ou 9. Le relâchement du cobalt et du nickel dans le volume de la solution était toujours moindre lorsque comparé au relâchement d’arséniate. Dans les premières 24 à 48 h de dissolution, le pH de la solution augmentait rapidement et ensuite diminuait légèrement jusqu’à ce qu’il approche un régime permanent. Lors de la dissolution dans la solution à pH 2, les concentrations aqueuses de Co, Ni et As augmentaient rapidement dans la première heure et ensuite diminuaient après 72 à 120 h. Après cette période, elles augmentaient graduellement une fois de plus et finalement approchaient un régime permanent. On a calculé les valeurs moyennes de Ksp en utilisant PHREEQC, avec une valeur de 10−34·02 (10−33·53–10−34·68) à 25°C pour l’érythrite et une valeur de 10−30·77 (10−29·83–10−32·57) à 25°C pour l’annabergite, et l’on a calculé les énergies libres de formation de Gibbs et à −3551·62 et −3506·68 kJ mol−1 respectivement.

Uranium levels in Cypriot groundwater samples determined by ICP-MS and α-spectroscopy

The uranium concentration and the isotopic ratio 238U/234U have been determined in Cypriot groundwater samples by ICP-MS after ultrafiltration and acidification of the samples and α-spectroscopy after pre-concentration and separation of uranium by cation-exchange (Chelex 100 resin) and electro-deposition on stainless steel discs. The uranium concentration in the groundwater samples varies strongly between 0.1 and 40 μg l−1. The highest uranium concentrations are found in groundwater samples associated with sedimentary rock formations and the obtained isotopic ratio 238U/234U varies between 0.95 and 1.2 indicating basically the presence of natural uranium in the studied samples. The pH of the groundwater samples is neutral to weak alkaline (7 < pH < 8) and this is attributed to the carbonaceous content of the sedimentary rocks and the ophiolitic origin of the igneous rocks, which form the background geology in Cyprus. Generally, in groundwaters uranium concentration in solution increases with decreasing pH (7 < pH < 8) and this is attributed to the fact that at lower pH dissolution of soil minerals occurs, and uranium, which is adsorbed or forms solid solution with the geological matrix enters the aqueous phase. This is also corroborated by the strong correlation between the uranium concentration and the electrical conductivity (e.g. dissolved solids) measured in the groundwaters under investigation.

In vitro Dissolution and in vivo Bioequivalence Evaluation of Two Brands of Isosorbide 5-mononitrate Sustained Release Tablets

The purpose of the present study was to test a sustained release-tablet newly formulated with synthetic paraffin and compare its bioequivalence to that of the Imdur® Long-Acting tablet, based on the guidelines of the Korean Food and Drug Administration.Dissolution test was performed in 4 different dissolution media. A LC/MS/MS method of isosorbide 5-mononitrate in human plasma was validated. In vivo bioequivalence tests of the 2 isosorbide 5-mononitrate tablets were performed in both preprandial and postprandial states.A comparative dissolution test gave similar results for both tablets in all dissolution media tested: 40% dissolution in pH 1.2 at 2 h and 80% dissolution in pH 4.0, pH 6.8, or water at 10 h. In a bioequivalence study to compare 2 tablets, the mean total area under the curve (AUCt) and peak concentration (Cmax) in the fasted state were 8 476.0 ng · h/mL and 540.4 ng/mL, respectively, for the Imdur® Long Acting Tablet 60 mg, and 8 701.4 ng · h/mL and 564.2 ng/mL, respectively, for the test tablet. The mean AUCt and Cmax in the fed state were 8 793.5 ng · h/mL and 559.9 ng/mL, respectively, for the Imdur® Long-Acting tablet 60 mg, and 8 639.8 ng · h/mL and 617.9 ng/mL, respectively, for the test tablet. The 90% confidence intervals using log transformed data were within the acceptable range of 0.8 - 1.25.Based on these statistical analyses, we conclude that the test tablet is bioequivalent to the Imdur® Long-Acting tablet 60 mg in both the preprandial and postprandial states.

Preparation and characterization of isosorbide 5-mononitrate extended-release tablets

The objective of this study was to prepare isosorbide 5-mononitrate tablets with an extended-release base using paraffin wax. The goal was to develop a tablet formulation equivalent to the commercially available Imdur® Long Acting Tablet 60 mg. We investigated the effect of paraffin wax on the dissolution rate of isosorbide 5-mononitrate and performed an in vitro dissolution test using the paddle method. The paddle stirring rates were varied from 50 to 150 rpm to mimic pre- and postprandial conditions and determine the effect of food uptake affects on drug absorption. In the dissolution study, isosorbide 5-mononitrate tablets with paraffin wax exhibited extended-release behaviors from 72 to 90 % over an 8-h period, of which the #4 formulation (110-mg paraffin wax) was comparable to the Imdur® Long Acting Tablet 60 mg. From the f 2 factor, the paddle stirring rate did not affect the dissolution both pH 1.2 and 6.8 between the formulation #4 and Imdur® Long Acting Tablet 60 mg for 10 h. The results suggest that the properties of oral extended-release tablet of isosorbide 5-mononitrate containing paraffin wax were comparable to those of the Imdur® Long Acting Tablet 60 mg, and satisfied the guidelines of the Korea Food and Drug Administration.

Microstructure of the paper nautilus (Argonauta nodosa) shell and the novel application of electron backscatter diffraction (EBSD) to address effects of ocean acidification

Electron backscatter diffraction (EBSD) is a powerful microscopic technique to characterise the crystallography of biomineralisation. Here, we use high-resolution EBSD to characterise one of the least studied shells in the ocean, the female argonaut brood chamber, and to examine the changes in shell microstructure in response to incubation in decreased pH conditions. The thin (225 μm) shell of Argonauta nodosa is magnesium calcite with an average magnesium content of ca. 5.1 Wt % MgCO3. EBSD and scanning electron microscopy (SEM) revealed that calcification of the shell is bidirectional with formation of irregular crystalline grains. Following a 2 week incubation in a range of pH treatments (pH, 8.1–7.2), shell fragment weight decreased by dissolution in pH ≤ 7.8. EBSD and SEM revealed altered shell crystallography and microstructure at pH ≤ 7.4 due to preferential etching down crystallite grain boundaries and a change in crystalline orientation on both the inner and outer shell surfaces. Our study highlights the value of EBSD for the detailed examination of biogenic carbonates and its potential use in the field of ocean acidification research.

Cyproterone Synthesis, Recognition and Controlled Release by Molecularly Imprinted Nanoparticle

In this study, we used novel synthetic conditions of precipitation polymerization to obtain nanosized cyproterone molecularly imprinted polymers for application in the design of new drug delivery systems. The scanning electron microscopy images and Brunauer-Emmett-Teller analysis showed that molecularly imprinted polymer (MIP) prepared by acetonitrile exhibited particles at the nanoscale with a high degree of monodispersity, specific surface area of 246 m(2) g(-1), and pore volume of 1.24 cm(3) g(-1). In addition, drug release, binding properties, and dynamic light scattering of molecularly imprinted polymers were studied. Selectivity of MIPs was evaluated by comparing several substances with similar molecular structures to that of cyproterone. Controlled release of cyproterone from nanoparticles was investigated through in vitro dissolution tests and by measuring the absorbance by HPLC-UV. The pH dissolution media employed in controlled release studies were 1.0 at 37 °C for 5 h and then at pH 6.8 using the pH change method. Results show that MIPs have a better ability to control the cyproterone release in a physiological medium compared to the non molecularly imprinted polymers (NMIPs).

Formulation and characterization of calcium chloride guar gum microsphere of theophylline

Aim: The aim of the present work was to formulate and characterize an effective colonic drug delivery system for nocturnal asthma based on the time- and pH-dependent system. Materials and Methods: The microsphere of calcium chloride guar gum was prepared by using theophylline. It was prepared by the method of emulsification and coating was done by the method of solvent evaporation with the pH-sensitive eudragit polymers. The prepared microsphere was characterized by particle size, surface morphology, entrapment efficiency, and degree of swelling. Results: The drug release was confirmed by the in vitro drug release in various pH progression medium and dissolution medium. The controlled release of theophylline after a lag time was achieved with developed formulation for colon drug delivery. Conclusion: The pH-dependent solubility behavior of eudragit and gelling properties of guar gum are found to be responsible for delaying the release.

Comparison of HPMC based polymers performance as carriers for manufacture of solid dispersions using the melt extruder

Preparation of amorphous solid dispersions using hot-melt extrusion process for poorly water soluble compounds which degrade on melting remains a challenge due to exposure to high temperatures. The aim of this study was to develop a physically and chemically stable amorphous solid dispersion of a poorly water-soluble compound, NVS981, which is highly thermal sensitive and degrades upon melting at 165 °C. Hydroxypropyl Methyl Cellulose (HPMC) based polymers; HPMC 3cps, HPMC phthalate (HPMCP) and HPMC acetyl succinate (HPMCAS) were selected as carriers to prepare solid dispersions using hot melt extrusion because of their relatively low glass transition temperatures. The solid dispersions were compared for their ease of manufacturing, physical stability such as recrystallization potential, phase separation, molecular mobility and enhancement of drug dissolution. Two different drug loads of 20 and 50% (w/w) were studied in each polymer system. It was interesting to note that solid dispersions with 50% (w/w) drug load were easier to process in the melt extruder compared to 20% (w/w) drug load in all three carriers, which was attributed to the plasticizing behavior of the drug substance. Upon storage at accelerated stability conditions, no phase separation was observed in HPMC 3cps and HPMCAS solid dispersions at the lower and higher drug load, whereas for HPMCP, phase separation was observed at higher drug load after 3 months. The pharmaceutical performance of these solid dispersions was evaluated by studying drug dissolution in pH 6.8 phosphate buffer. Drug release from solid dispersion prepared from polymers used for enteric coating, i.e. HPMCP and HPMCAS was faster compared with the water soluble polymer HPMC 3cps. In conclusion, of the 3 polymers studied for preparing solid dispersions of thermally sensitive compound using hot melt extrusion, HPMCAS was found to be the most promising as it was easily processible and provided stable solid dispersions with enhanced dissolution.

Effect of structural isomerism and polymer end group on the pH-stability of hydrogen-bonded multilayers

Association of tannic acid (TA) with structurally isomeric poly(N-isopropylacrylamide) (PNIPAM) and poly(2-isopropyl-2-oxazoline) (PIPOX) has been examined at surfaces to understand the effect of different molecular arrangements in a polymer repeating unit of structural isomers on the construction and pH-stability of hydrogen-bonded multilayers. Films were fabricated using layer-by-layer (LbL) technique through hydrogen-bonding interactions primarily between carbonyl groups of neutral polymers and hydroxyl groups of TA molecules at pH 2. PIPOX and TA formed thinner and more stable films in the pH scale with a critical dissolution pH of 9 when compared to films of PNIPAM and TA with a critical pH of 8. The differences in the thickness and pH-stability were due to different conformational behavior of PNIPAM and PIPOX in water which affects the accessibility of carbonyl groups for participation in the hydrogen bonding and the number of binding sites between the polymer pairs. Addition of electrostatic interactions by introducing amino groups only at the PIPOX chain end shifted the critical dissolution pH to higher values and resulted in gradual dissolution of the films in a wide pH range of 9–12. Such films hold promise for use in biomedical field due to biocompatibility and lower critical solution temperature (LCST) behavior at near physiological temperature of PNIPAM and PIPOX together with the pH-response of the hydrogen-bonded films.