X-Ray Investigations of the Intermetallic Phases CaCd1-x Tlx and Caln1-x Tlx and Knight Shift Measurements of 205Tl- and 113Cd-NMR in the System CaCd1-x Tlx

The quasibinary systems CaCd1-xTlx and CaIn1-xTlx- form continuous series of solid solutions for all concentrations x: 0 ≦ x ≦ 1. All alloys of both systems crystallize with space group Oh1-PmSm and one formula unit per unit cell (CsCl-type structure). Considerable deviations from Vegard’s law occur for CaCd1-x Tlx, while they are negligible for CaIn1-x Tlx. No sign for the appearance of superstructures was found in either system after equilibrating them at 300 °C for two hours. In the system CaCd1-xTlx the Knight shift Ks of the 205Tl- and 113Cd-NMR was measured at room temperature as a function of x. Saturated Tl(CH3CO2)- and Cd(NO3)2 solutions served as reference samples. The Knight shift of the 205Tl-resonance increases remarkably with increasing concentration x, whereas the Knight shift of the 113Cd-NMR decreases slightly with increasing x. No simple qualitative explanation is found for Ks(Tl) =f(x) and Ks(Cd) =f(x)

A Theoretical Modeling of the Static and Dynamic Polarizability of O2- in Large and Complex Oxides

A time-dependent approach is employed in conjunction with a crystal potential model to study the environment-specific optical linear response of the O2- ions in a number of cubic oxides with varying number of constituents, unit-cell dimension and degree of complexity. It is shown that the static polarizability of the anion may vary significantly depending on the position of the anion within the unit-cell. Due to neglect of overlap compression, our method has limited success in predicting the refractive indices of large crystals of complex structures. For small binary oxides the frequency-dependent polarizability of the O2- ion is found to exhibit the first poles close to the ultraviolet absorption edges ascribed to the lowest excitonic transitions in these crystals.

Band Structure of CaCd and CaTl and the Knight Shift of 113Cd- and 205Tl-NMR in the System CaCd1-x Tlx

The energy bands of ordered CaCd and CaTl have been calculated by the nonrelativistic augmented plane wave (APW) method. The electron structure in the system CaCd1-xTlx is deduced from these calculations by using the rigid band model for the phases with 0<x<1. The band structures of CaCd and CaTl are similar to the valence bands of other phases of the CsCl-type. From the energy eigenvalues the electronic density of states curve, the partial densities of states curves, and the Fermi energy have been obtained. For states near the Fermi surface the spin density at the position of the Cd- and Tl-nuclei has been determined. The Knight shift Ks of the 113Cd-NMR and the 205Tl-NMR in the system CaCd1-xTlx has been calculated as a function of x. The slope of the curve Ks (x) for the Cd-NMR is equal for experimental and theoretical results. The absolute value of the calculated Knight shift is about a factor of 1.4 too small. Only the direct term to the Knight shift has been calculated. Relativistic effects have been included by a scale factor. It has not been possible to explain the shape of the function (2) for the Tl-NMR, since a full relativistic APW calculation is necessary for CaTl

Current Status of Theory of Nuclear Quadrupole Interaction in Metallic Systems

This paper deals with the current status of understanding of the factors that determine the origin of nuclear quadrupole interactions in metallic systems. The major emphasis is on pure metals in which there is currently better understanding of the origin of the electric field gradient (EFG) at the nuclear sites. The procedures for the determination of the electron densities that lead to the electronic contributions to the EFG’s is discussed as well as the quantitative procedures for incorporation of antishielding effects. The nature of agreement between theory and experiment is examined by considering the hexagonal close packed metals beryllium, magnesium, zinc and cadmium. The sensitiveness of the calculated EFG to the procedure used for obtaining electron densities is discussed in beryllium using orthogonalized plane wave and augmented plane wave procedures. The nature of agreement between theory and experiment currently attainable for semi-metals and semiconductors is discussed. The bearing of some of the results in these latter systems by procedures dealing with clusters of atoms to simulate the infinite solid on the future of such procedures for imperfect systems and surfaces is commented upon. A brief discussion is presented about the various possible contributors to the temperature dependence of EFG’s in pure metals and comparison is made between theory and experiment for zinc and cadmium. The factors that can contribute to the EFG’s in imperfect metallic systems, including alloys, at both host and impurity nuclei are discussed, and some of these factors are illustrated by considering two examples of these systems, EFG ’s at host Al and Cu nuclei due to mu mesons introduced in the metal and at impurity nuclei in alloys involving cadmium metal host. The concluding section discusses directions in which further efforts are needed to improve our theoretical understanding of both pure metals and imperfect metallic systems.

Augmented Plane Wave Study of Electric Field Gradients in Non-cubic Metals

The electric field gradient (EFG) in body-centered tetragonal Indium metal and hexagonal closed packed Beryllium metal is calculated on the basis of a full potential scalar relativistic augmented plane wave procedure. The various contributions to the EFG in simple metals are discussed. The total EFG in In metal found theoretically is equal to qtheor = 2.67 x 1021 Vm-2 . This value agrees well with the experimental data. Using the quadrupole moment Q deduced from the hyperfine splitting of the muon X-ray spectra one gets g exp = 2.46 x 1021 Vm-2 . The valence electrons of Indium give a direct contribution of qel = 2.72 x 1021 Vm-2 , whereas the direct ionic contribution q ion is much smaller and has opposite sign: qion = -0.01 x 1021 Vm-2 . There is a small net shielding contribution of qsh = -0.03 x 1021 Vm-2 to the EFG composed of the ionic contribution gsh. ion = -0.39 x 1021 Vm- 2 and the valence electron contribution qsh,ve = 0.36 x 10 21 Vm-2 .

Structure, Electronic Structure and Defect Formation Energies of LixCo1-yNiyO2 as a Function of x (0ACTA ACUST UNITED AC 2009. [DOI: 10.1524/zpch.2009.6082]

LixCoO2 and LixNiO2 (0.5<x<1) are prototype cathode materials in lithium ion batteries.Both systems show degradation and fatigue during electrochemical cycling. We have performed band structure calculations based on density-functional theory for a series of compounds Lix(Co,Ni)O2 (0<x<1). The distribution of the transition metals (TM) cobalt and nickel on TM sites as well as the electronic structure of these compounds is investigated with focus on the change of oxidation states of cobalt, nickel and oxygen during lithium de-intercalation. We also study the total energy as a function of the lithium content x, including the vibrational energy E v and the formation energy of lithium vacancies E(VLi). It is found that E v is small compared to E(VLi) and that E(VLi) is increasing with increasing x for all systems.

A First-Principles Investigation of the Electronic Structure of Trivalent Rare Earth Ions in Gallium Nitride

Using first-principles electronic structure methods, we have investigated the electronic structure and associated properties of Pr3+, Nd3+, Eu3+, Tb3+, Dy3+ and Er3+ substituting for Ga3+ in GaN. It is found that these rare earth ions (RE3+) are stable at the Ga site in tetrahedral coordination with nitrogen atoms. The nitrogen ligands move away from the RE3+ site to allow for the large ionic radii of the RE3+ ions. The equilibrium bond lengths of RE–N are found to vary between 2.15 to 2.30Å in good agreement with structural data available for Eu3+, Tb3+ and Er3+. Using the calculated energy bands, excitation energies for the 4f→5d transition have also been predicted. Most of these energies are larger than the band gap of GaN and cannot be exploited in transferring host excitation energies to the RE3+ ions.

Influence of Compacted Hydrophobic and Hydrophilic Colloidal Silicon Dioxide on Tableting Properties of Pharmaceutical Excipients

The effect of noncompacted and compacted hydrophilic as well as hydrophobic colloidal silicon dioxide (CSD) on tableting properties of three different pharmaceutical excipients used for direct compression, namely, Avicel PH 101, Starch 1500, and Tablettose 80, was investigated. Binary powder mixtures containing 0.5% CSD and 99.5% excipient were compressed on an instrumented single-punch tablet press, and the radial tensile strength/compaction load profiles were examined. The Ryshkewitch-Duckworth relationship shows that the influence of CSD on tablet strength was dependent on the hydrophobic and hydrophilic nature of the CSD and on the compaction characteristics of the excipients. Tablets from each excipient with and without CSDs were subjected to different levels of relative humidity at 20 degrees C for 7 days. The sorption isotherms and the radial tensile strengths of the tablets after the storage period showed that neither hydrophilic nor hydrophobic CSD influenced the tablet properties of Avicel PH 101, Starch 1500, and Tablettose 80. Moreover, ternary powder mixtures containing magnesium stearate as a third component were compressed in order to study the influence of CSD on the deleterious effect of magnesium stearate on the interparticle bonding. The radial tensile strength/compaction load profiles and the residual and ejection forces of tablets made from ternary mixtures showed that CSD eliminated the negative effect of magnesium stearate on interparticle bonding while maintaining the lubrication action, in a manner that was affected by its hydrophobicity/hydrophilicity and by the particle deformation properties of the excipient upon compression.

Visualization and analysis of the release mechanism of shellac coated ascorbic acid pellets

Shellac coated sustained release ascorbic acid containing pellets were investigated using scanning electron microscopy in order to visualize the release mechanism and to establish a correlation to dissolution data. Scanning electron micrograph pictures revealed different drug release profiles of individual pellets. Single pellet dissolution measurements demonstrated that the release profile of the encapsulated dosage form, containing approximately 400 pellets per capsule, is a combination of different release profiles of all individual pellets. The release of ascorbic acid occurred only in some small spots on the surface area of the pellets and could be visualized by the reduction of silver ions from an aqueous silver nitrate solution. These spots could be identified as defects in the shellac sustained release film using scanning electron microscopy. In further trials, the dissolution rate of an individual pellet could be related to the number and dimension of holes in its membrane. In conclusion, the release is characterized by surface defects and scanning electron microscopy studies are a useful tool to get new information for a better understanding of the drug release.

Antiviral activities of some Ethiopian medicinal plants used for the treatment of dermatological disorders

Acokanthera schimperi (Apocynaceae), Euclea schimperi (Ebenaceae), Inula confertiflora (Asteraceae), Melilotus elegans (Leguminosae), and Plumbago zeylanica (Plumbaginaceae), are some of the medicinal plants used in Ethiopia for treatment of various skin disorders. In this study, the antiviral activities of the 80% methanolic extracts of these plants have been examined against coxsackievirus B3 (CVB3), influenza A virus and herpes simplex virus type1 Kupka (HSV-1) using cytopathic effect (CPE) inhibitory assays in HeLa, MDCK, and GMK cells, respectively. In parallel, the cytotoxicity was quantified using a crystal violet uptake assay. The antiviral activity of the most active compound was confirmed with plaque reduction assays. The results revealed that the extracts of Acokanthera schimperi and Euclea schimperi showed antiviral activity against all three tested viruses albeit with unequal efficacy. Whereas the Acokanthera schimperi extract exhibited the strongest activity against CVB3, the extract of Euclea schimperi inhibited influenzavirus A replication most effectively. A weak anti-influenzavirus A activity was also exhibited by the other plant extracts tested. In addition, CVB3 was inhibited by the extracts of Plumbago zeylanica and HSV-1 by Inula confertiflora. Thus, the extracts of these plants, particularly those of Acokanthera schimperi, Euclea schimperi and Inula confertiflora which showed activity against CVB3 and HSV-1 support their traditional use in the treatment of skin diseases of viral origin.

High anti-inflammatory activity of harpagoside-enriched extracts obtained from solvent-modified super- and subcritical carbon dioxide extractions of the roots of Harpagophytum procumbens

Solvent-modified carbon dioxide extractions of the roots of Harpagophytum procumbens have been investigated with respect to extraction efficiency and content of harpagoside, and compared with a conventional extract. The effects of pressure, temperature, type and concentration of the modifier have been examined. Two extraction steps were necessary in order to achievehigh anti-inflammatory harpagoside-enriched extracts. The first extraction step was carried out in the supercritical state using carbon dioxide modified with n-propanol to remove undesired lipophilic substances. The main extraction was performed either in the supercritical or in the subcritical state with carbon dioxide modified with ethanol. The supercritical fluid extraction resulted in extracts containing up to 30% harpagoside. The subcritical extracts showed a harpagoside content of ca. 20%, but the extraction yield was nearly three times greater compared with supercritical conditions. The total harpagoside recovery resulting from the sum of the extract and the crude drug residue was greater than 99% in all experiments. The conventional extract and two carbon dioxide extracts were tested for in-vitro inhibition of 5-lipoxygenase or cyclooxygenase-2 biosynthesis. Both carbon dioxide extracts showed total inhibition on 5-lipoxygenase biosynthesis at a concentration of 51.8 mg/L. In contrast, the conventional extract failed to show any inhibition of 5-lipoxygenase biosynthesis.

Comparison between HPLC and HPTLC-densitometry for the determination of harpagoside from Harpagophytum procumbens CO2-extracts

Carbon dioxide (CO(2)) extracts of the secondary roots of Harpagophytum procumbens were quantified by high performance liquid chromatography (HPLC) and high performance thin layer chromatography (HPTLC). An isocratic HPLC method was used for the quantification of the iridoid glucoside harpagoside at 278 nm. A HPTLC assay was developed for the determination of harpagoside after coloration at 509 nm. The diode array detection of both analytical assays were used to examine the purity of harpagoside peaks and compared with the standards, respectively. The assays provide good accuracy, reproducibility and selectivity for the quantitative analysis of harpagoside. The harpagoside contents of 15 different CO(2)-extracts were compared by HPLC and HPTLC-densitometry. The quantitative results of both analytical methods did not show any statistical significance between each other, although a trend to slightly lower mean values could be found for the HPTLC method.

Supercritical carbon dioxide extraction of chamomile flowers: extraction efficiency, stability, and in-line inclusion of chamomile-carbon dioxide extract in beta-cyclodextrin

The extraction of chamomile flowers using supercritical carbon dioxide was investigated with respect to extraction efficiency and compared with solvent extraction. The stability of matricine, a sensitive constituent of the essential oil of chamomile, in these extracts was studied during storage at different temperatures over 6 months. Matricine was stable at -30 degrees C. A slight decrease (80-90% recovery) occurred at +5 degrees C, whereas complete decomposition of matricine took place within 3-4 months at room temperature and at +30 degrees C, respectively. An in-line inclusion of chamomile constituents in beta-cyclodextrin (beta-CD) during the extraction process was assessed and inclusion rates between 40 and 95% were obtained depending on the amount of beta-CD and the type of chamomile constituent. No further stabilization of matricine in the carbon dioxide extract/beta-CD complexes was achieved. High residual water contents in the complexes even after freeze-drying were identified as accelerating the decomposition. In addition, the extractability of flavonoids, such as apigenin and apigenin-7-glucoside, was determined. Apigenin-7-glucoside, the more hydrophilic substance, was not extractable with pure carbon dioxide and showed a recovery of 11% using methanol modified carbon dioxide (18%, w/w) at 60 degrees C and 380 bar. Extraction conditions in the two-phase region of the binary mixture carbon dioxide-methanol (70 degrees C, 100 bar) led to a drastic change in fluid polarity and hence extractability increased to 92-95%.

Standardisation and physicochemical characterisation of the extracts of seeds of Glinus lotoides

Extraction methods were standardised for saponin-containing extracts from the seeds of Glinus lotoides and the effects of some extraction process variables, such as the extracting solvent (various concentrations of methanol in water) and method of extract drying (freeze-drying and vacuum oven-drying), on the physical properties of the extracts were investigated. Physicochemical properties, namely particle size and size distribution, morphology, water uptake profiles and sorption isotherms, densities, flow properties and compaction profiles, of the crude dry extracts of 60% methanol (extract A), 70% methanol (extract B) and 80% methanol (extract C) were investigated. The average particle sizes (X50) of extracts A, B and C were found to be 68.4, 92.1 and 68.5 microm, respectively. Scanning electron micrographs of freeze-dried and vacuum oven-dried extract A showed that the particles are irregular in shape and are compact masses with sharp edges. The percent water uptake by the crude extracts was found to increase with an increase in relative humidities, while the hygroscopicity increased with decreasing methanol ratio of the extracting solvent. The bulk and the true densities of the three extracts (A, B and C) ranged from 0.66 to 0.67 and 1.49 to 1.50 g/ml, respectively. The tapped density (0.94 g/ml) and hence the porosity (56.0%), Carr's index (29.8%) and Hausner ratio (1.42) of extract A were greater than those of extracts B and C. Measurements of angle of repose indicated that all of the extracts exhibit poor flow properties. Compaction studies revealed that extract C has higher compactibility than extracts A and B.

Phase solubility studies of pure (-)-alpha-bisabolol and camomile essential oil with beta-cyclodextrin

(-)-Alpha-bisabolol was found to form an inclusion complex with beta-cyclodextrin (beta-CD) in solution as well as in the solid state. To investigate molecular associations of beta-CD with pure (-)-alpha-bisabolol or (-)-alpha-bisabolol as a component of camomile essential oil, phase solubility studies were undertaken. A B(s) type solubility with an apparent complex constant of 273 M(-1) for the pure (-)-alpha-bisabolol and 304 M(-1) for (-)-alpha-bisabolol as a constituent of the essential oil were obtained. The two curves in the phase solubility diagram reach their plateau at different concentrations of (-)-alpha-bisabolol, 7.04 x 10(-4) M for the pure substance and 2.88 x 10(-4) M for the substance as a component of the essential oil. Although the shapes of the curves are almost similar, the intrinsic solubility's of pure (-)-alpha-bisabolol (4.85 x 10(-4) M) and (-)-alpha-bisabolol as a component of the essential oil (1.82 x 10(-4) M) differ significantly. An inclusion complex having a stoichiometric composition of 2:1 (beta-CD: drug) was obtained. A mechanism of complexation has been proposed on the basis of the stability constant calculated from phase solubility data and the stoichiometric ratio of the solid state complexation.

In vitro deposition of the respirable fraction of dry powder inhalations determined by laser diffractometry and inertial impaction

Particle size analysis of drug and excipient is of particular interest for dry powder inhalation (DPI) formulations development and quality control. In this work, the deposition in the upper, the medium and the lower (i.e. the respirable fraction) Twin Impinger compartments of sodium cromoglycate (SCG), lactose (as excipient) and a 1:1 mixture thereof was determined by chemical analysis using a DPI device--the Micro-hale--and compared with the results obtained by laser diffractometry for the same fractions. The analytical method for the SCG determination consisted of ultraviolet spectrophotometry and, for the lactose, high performance liquid chromatography with refractive index detection was used. Laser diffractometry as a quickly operating routine method can substitute the chemical analysis in order to evaluate the respirable fraction, under the conditions of the present work and therefore making formulation development easier and quicker.

Rapid quantification of constituents in St. John's wort extracts by NIR spectroscopy

A quantitative near-infrared reflectance spectroscopy (NIRS) method was established for the determination of two major constituents (hyperforin and I3,II8-biapigenin) in St. John's wort extracts. Hyperforin was chosen due to the fact that it is found in a concentration range from 1 to 5%, a common one for NIRS determinations. I3,II8-Biapigenin on the other hand was selected as a constituent with very low concentrations (0.1-0.7%) but an extensive chromophore that allows very precise measurements in the ultraviolet (UV) and thus exact reference values that are vital for proper NIRS calibrations. Reference measurements were performed by reversed-phase high performance liquid chromatography (HPLC), determining the constituents' content in 35 pharmaceutical dry extracts of different origins. The reference method was validated according to the ICH guideline Q2B. Using partial-least squares (PLS) regression a multivariate calibration was done for the two ingredients each (PLS1). Satisfactory calibration statistics were obtained for hyperforin with a root mean square error of calibration (RMSEC) of 0.17 and a root mean square error of prediction (RMSEP) of 0.22 at a concentration range from 1 to 6% in the dry extracts. Due to the very low concentrations of I3,II8-biapigenin the accuracy of prediction is somewhat lower. However, it is possible to obtain very good results and reliable prediction by dividing the concentration range at 0.35%. The study emphasizes the potential of NIRS as a rapid and highly effective alternative method to conventional quantitative analysis of plant extracts.

Quantitative analysis of the active components and the by-products of eight dry extracts of Hypericum perforatum L. (St John's Wort)

The major components of eight different batches of commercially available dry extracts of Hypericum perforatum L. were quantified. Hyperforin (1), hypericin (2) and flavonoids, which are considered to play key roles in the treatment of mild and moderate depressive disorders, were determined by HPLC methods. The contents of 1, 2 and flavonoids were found to be in the range of 1.3-3.9%, 0.19-0.30%, and 4.8-11.4%, respectively. Generally extracts contained, besides the so-called active components, a wide variety of by-products which may act partially as co-effectors and affect the technological properties of the extracts. Water-soluble sugars form one of the main groups of these by-products, and a procedure for the purification and quantification of such sugars in H. perforatum using HPLC with refractive index detection has been established. Native fructose, glucose and sucrose, as well as lactose added during the processing of the extracts, were determined. The total sugar content in the dry herbal extracts varied from 19 to 25% by weight. Further, citric acid (0.9-2.3%) and malic acid (2.3-3.1%) were determined by HPLC, tannins (6.2-9.0%) and total ash (4.9-8.4%) were quantified according to the methods described in the European Pharmacopoeia, and the content of the total protein (3.9-8.3%) was estimated by elemental analysis. Thus, 60-70% of the compounds of the H. perforatum dry extracts have been quantified.

Pharmaceutical applications of supercritical carbon dioxide

The appearance of a supercritical state was already observed at the beginning of the 19th century. Nevertheless, the industrial extraction of plant and other natural materials started about twenty years ago with the decaffeination of coffee. Today carbon dioxide is the most common gas for supercritical fluid extraction in food and pharmaceutical industry. Since pure supercritical carbon dioxide is a lipophilic solvent, mixtures with organic solvents, especially alcohols, are used to increase the polarity of the extraction fluid; more polar compounds can be extracted in this way. The main fields of interest are the extraction of vegetable oils from plant material in analytical and preparative scale, the preparation of essential oils for food and cosmetic industry and the isolation of substances of pharmaceutical relevance. Progress in research was made by the precise measurement of phase equilibria data by means of different methods. Apart from extraction, supercritical fluid chromatography was introduced in the field of analytics, as well as micro- and nanoparticle formation using supercritical fluids as solvent or antisolvent. This review presents pharmaceutical relevant literature of the last twenty years with special emphasis on extraction of natural materials.

[Protein analysis of enzyme tablets]

Enzyme tablets with butyrylcholine esterase (CHE) and peroxidase (POD) partly lose enzymatic activity during compaction at a pressure of 495 MPa. Compared to solutions of the original enzyme, no changes of ultraviolet absorbance and fluorescence intensity in the tablet solutions were found. Only small changes were observed in the far ultraviolet circular dichroism spectra. Neither missing nor additional bands were detected with polyacrylamide gel electrophoresis. Heated (150 degrees C) solid starting material with CHE and POD showed still part of its original enzymatic activity. The ultraviolet absorbance increased with continued heating until precipitation occurred. The circular dichroism spectra are changed clearly.

Polymorphic changes of thiamine hydrochloride during granulation and tableting

Thiamine hydrochloride was granulated using an instrumented fluidized bed granulator (Hüttlin HKC 05-TJ). Granules consisting of pure thiamine hydrochloride were produced using an aqueous solution of thiamine hydrochloride as the granulating liquid. The effects of process variables such as inlet air temperature, spray rate, and amount of granulating liquid on granule properties are described. Particle size distributions of granules depended mainly on the amount of granulating liquid sprayed into the powder bed. Granules were tableted on a rotary tablet press at four different compression forces. Crushing strengths and disintegration times of all tablets were found to be very low after manufacture, but increased considerably after 4 months of storage at room temperature. Granular materials showed "caking" under the same storage conditions. These changes could be attributed to alterations of the polymorphic form of thiamine hydrochloride. The water-free form, being present directly after granulation, absorbs humidity very fast and is transformed into the monohydrate, which is stable at room temperature. Loss of water takes place during the drying phase of the granulation process and on storage of the substance at temperatures of 50 degrees C and 80 degrees C. During storage at room temperature while exposed to humidity, a transformation into the hemihydrate was observed. This polymorph is transformed during thermal analysis at about 190 degrees C to a water-free form that is stable at higher temperatures.

The effect of conjugated linoleic acid on platelet function, platelet fatty acid composition, and blood coagulation in humans

Despite extensive research on conjugated linoleic acid (CLA) showing multiple beneficial effects in animal models, little is known about the role of dietary CLA in human health. To investigate if the beneficial effects of CLA seen in animal models are relevant to humans, we conducted a study with 17 healthy female volunteers who lived in the Metabolic Research Unit of the Western Human Nutrition Research Center for 93 d. This paper reports only the results from this study that are related to the effects of CLA supplementation on blood coagulation, platelet function, and platelet fatty acid composition. Throughout the study, the subjects were fed a low-fat diet (30 en% fat, 19 en% protein, and 51 en% carbohydrate) consisting of natural foods with the recommended dietary allowances for all known nutrients. After a 30-d stabilization period, subjects were randomly assigned to either an intervention group (n = 10) whose diet was supplemented with 3.9 g/d of CLA or a control group (n = 7) who received an equivalent amount of sunflower oil consisting of 72.6% linoleic acid with no detectable CLA. Platelet aggregation was measured in platelet-rich plasma using adenosine diphosphate, collagen, and arachidonic acid agonists. No statistical difference was detected between the amount of agonist required to produce 50% aggregation of platelet-rich plasma before and after the subjects consumed the CLA, with the exception of a decrease in response to collagen. This decrease was found in both control and intervention groups with no significant difference between the groups, suggesting that both linoleic acid (sunflower oil) and CLA might have similar effects on platelet function. The prothrombin time, activated partial thromboplastin time, and the antithrombin III levels in the subjects were determined. Again, there was no statistically significant difference in these three parameters when pre- and post-CLA consumption values were compared. The in vivo bleeding times were also unaffected by CLA supplementation (10.4 + 2.8 min pre- and 10.2 + 1.6 min postconsumption). Platelet fatty acid composition was not markedly influenced by the consumption of dietary CLA, although there was a small increase in the amount of the 9 cis,11 trans-18:2 isomer normally present in platelets after feeding CLA for 63 days. In addition, small amounts of the 8 trans,10 cis-18:2 and the 10 trans,12 cis-18:2 isomers were detected in the platelets along with traces of some of the other isomers. Thus, when compared to sunflower oil, the blood-clotting parameters and in vitro platelet aggregation showed that adding 3.9 g/d of dietary CLA to a typical Western diet for 63 d produces no observable physiological change in blood coagulation and platelet function in healthy adult females. Short-term consumption of CLA does not seem to exhibit antithrombotic properties in humans.

The effect of conjugated linoleic acid on plasma lipoproteins and tissue fatty acid composition in humans

Conjugated linoleic acid (CLA) has been suggested by some animal studies to possess antiatherogenic properties. To determine, in humans, the effect of dietary CLA on blood lipids, lipoproteins, and tissue fatty acid composition, we conducted a 93-d study with 17 healthy female volunteers at the Metabolic Research Unit of the Western Human Nutrition Research Center. Throughout the study, subjects were fed a low-fat diet [30 energy percent (en%) fat, 19 en% protein, and 51 en% carbohydrate] that consisted of natural foods with the recommended dietary allowances for all known nutrients. After a 30-d stabilization period, subjects were randomly assigned to either an intervention group (n = 10) supplemented daily with capsules containing 3.9 g of CLA or a control group (n = 7) that received an equivalent amount of sunflower oil. The CLA capsules (CLA 65%) contained four major cis/trans geometric isomers (11.4% 9 cis-,11 trans-18:2; 10.8% 8 trans-,10 cis-18:2; 15.3% 11 cis-,13 trans-18:2; and 14.7% 10 trans-,12 cis-18:2) and their corresponding cis/cis (6.74% total) and trans/trans (5.99% total) varieties in smaller amounts. Fasting blood was drawn on study days 30 (end of the stabilization period), 60 (midpoint of the intervention period), and 93 (end of the intervention period). Adipose tissue samples were taken on days 30 and 93. CLA supplementation for 63 d did not change the levels of plasma cholesterol, low density lipoprotein cholesterol, high density lipoprotein cholesterol, and triglycerides. The weight percentage of CLA in plasma increased from 0.28 +/- 0.06 to 1.09 +/- 0.31 (n = 10, P < 0.05) after the supplementation. The 9 cis-,11 trans-isomer was the most prominent variety followed by the 11 cis-,13 trans- and 10 trans-,12 cis-isomers in lesser amounts. CLA in adipose tissue was not influenced by the supplementation (0.79 +/- 0.18 to 0.83 +/- 0.19 wt%) (n = 10) and the 9 cis-,11 trans-variety was the only isomer present. Thus, contrary to findings from some animal studies, CLA does not seem to offer health benefits, in the short term, regarding the prevention of atherosclerosis in humans. CLA supplementation for 2 mon did not alter the blood cholesterol or lipoprotein levels of healthy, normolipidemic subjects. The supplementation did increase CLA in the plasma but only 4.23% of the ingested CLA was present in the plasma at any given time. No adverse effect of CLA supplementation was detected in this study.

Investigations of Nuclear Quadrupole Interaction in BaMgAl10O17:Eu2+

Local environments of divalent europium ions in β-lattice of barium magnesium aluminate, BaMgAl

Development of disintegrating multiple-unit tablets on a high-speed rotary tablet press

Enteric coated bisacodyl pellets were compressed into divisible disintegrating tablets on a high speed rotary tablet press and investigated for pellet damages. The degree of pellet damages was examined via the bisacodyl dissolution during the acid treatment of' the drug release test for enteric coated articles according to USP 23. The damages depended on the type of filler-binder used and settings of the tablet press. Avicel PH 101 proved to be the most suitable filler-binder, effecting homogeneous distribution of the pellets within the tablets, as could be shown by image analysis of coloured pellets. The speed of the tablet press had noo influence on the pellet damages using Avicel PH 101 as a filler-binder, however, tablets containing 70% (w/w) of coated pellets did not fulfil the requirements of USP 23, despite optimum elasticity and coating thickness of a new Eudragit FS 30 D coating. Reducing the proportion of pellets to 60% per tablet, less than 10% of bisacodyl were released within 2 h during acid treatment thus fulfilling the requirements of the USP 23.

Evaluation of validation of a fully instrumented Hüttlin HKC 05-TJ laboratory-scale fluidized bed granulator

The instrumentation and validation of a laboratory-scale fluidized bed apparatus is described. For continuous control of the process, the apparatus is instrumented with sensors for temperature, relative humidity (RH), and air velocity. Conditions of inlet air, fluidizing air, product, and exhaust air were determined. The temperature sensors were calibrated at temperatures of 0.0 degree C and 99.9 degrees C. The calibration of the humidity sensors covered the range from 12% RH to 98% RH using saturated electrolyte solutions. The calibration of the anemometer took place in a wind tunnel at defined air velocities. The calibrations led to satisfying results concerning sensitivity and precision. To evaluate the reproducibility of the process, 15 granules were prepared under identical conditions. The influence of the type of pump used for delivering the granulating liquid was investigated. Particle size distribution, bulk density, and tapped density were determined. Granules were tableted on a rotary press at four different compression force levels, followed by determination of tablet properties such as weight, crushing strength, and disintegration time. The apparatus was found to produce granules with good reproducibility concerning the granule and tablet properties.

Factors influencing capping and cracking of mefenamic acid tablets

The tendency of capping and longitudinal cracks of mefenamic acid tablets was evaluated in relation to the amount of the binder, the influence of the granulation technique, and the relative humidity of the granules. Tablets made from fluidized bed granules using methylcellulose in the granulating liquid showed significantly lower capping and longitudinal cracks than tablets from conventional granules prepared by wet granulation using methylcellulose as a dry binder.

Some physicochemical properties of mefenamic acid

Mefenamic acid is a problematic drug in granulation, tableting, and dissolution due to its poor solubility, hydrophobicity, and tendency to stick to surfaces. In most cases, the specifications of a drug by the pharmacopoeia include identification and purity, but they do not describe the physicochemical drug properties precisely. To characterize the mefenamic acid particle size, surface area measurements, X-ray pattern, differential scanning calorimetry (DSC), wettability, crystal habit, and compression behavior of different batches from two manufacturers were investigated. Due to larger particle size and better wettability, mefenamic acid of Il Yang type was easier to handle in a granulation process. The compression behavior of both types was nearly the same, although particle size, crystal habit, and wettability were very different.

Interactions during aqueous film coating of ibuprofen with aquacoat ECD

During the development of a coated ibuprofen formulation a sticking tendency occurred when applying Aquacoat ECD. This interaction indicated the formation of a eutectic mixture. The compatibility of the components of Aquacoat ECD with ibuprofen was investigated by differential scanning calorimetry. Cetyl alcohol, a stabilizing excipient in Aquacoat, was found to form a eutectic system with ibuprofen. It was characterized by the construction of a phase diagram with 33 mol% ibuprofen and an onset temperature of 40.5 degrees C. Wide-angle X-ray diffraction was used to identify the polymorphic forms of cetyl alcohol. The results confirmed the amorphous state in the aqueous dispersion in contrast to the beta(0)- and gamma(4)-polymorphs of solid cetyl alcohol.

Development of matrix-based theophylline sustained-release microtablets

Microtablets containing high theophylline content (from 60% to 80%) based on a Eudragit RS PO matrix were produced on a rotary tablet press. The influence of the compaction pressure, the plasticizer content used for the granulation of theophylline particles, and the amount of theophylline on the drug release were investigated. The effects of surface area and the addition of magnesium stearate as a hydrophobic agent on the drug release were studied. The storage stabilities of the release rate at room temperature and at 50 degrees C were also determined. Dissolution profiles expressed as percentage of theophylline dissolved were obtained over 8 hr in 900 ml of purified water at 37 degrees C and 75 rpm. It was observed that the compaction pressure (from 200 MPa to 250 MPa) had no effect on the theophylline release. The use of triethyl citrate (TEC) as a plasticizer in the granulation of theophylline enhanced the physical properties of the microtablets. Theophylline content in the range 60% to 80% did not affect the drug release. The theophylline release obtained was a function of the quotient surface area/tablet weight and therefore was dependent on the tablet diameter. To reduce the dissolution rates, magnesium stearate was added in a concentration up to 50% of the matrix material. Tablets of this hydrophobic formulation fulfilled the requirements of USP 23 for theophylline sustained-release preparations. Storage at room temperature for 3 months and at 50 degrees C for 2 months showed no significant influence on the theophylline release.

Optimization of crushing strength and disintegration time of a high-dose plant extract tablet by neural networks

Optimization of crushing strength and disintegration time of a high-dose plant extract tablet was reached after extensive experimentation. Effects of the processing parameters, like compression force and tooling, and also of the excipients were found to be significant. Best results for both disintegration time and crushing strength were obtained with a plant extract that was granulated by roller compaction before compression. To gain more information about the different effects, artificial neural networks (ANNs) and a conventional multivariate method (partial least squares [PLS]) were used for data analysis. The topologies of the neural networks of the feed-forward type were optimized manually and by pruning methods. All methods were tested for contemplated parameters, crushing strength, and disintegration time. In general, ANNs were found to be more successful in characterizing the effects that influence crushing strength and disintegration time than the conventional multivariate methods.

The influence of engravings on the sticking of tablets. Investigations with an instrumented upper punch

The purpose of this study was to investigate the influence of engravings on the sticking of tablets. Therefore, an instrumented upper punch capable of measuring the pull-off force, which occurs when the punch detaches itself from the upper surface of a tablet, was equipped with small cones of different angles between the punch face and the cones' lateral face. The cones could be screwed into a threaded hole at the center of the punch face. The adhesion forces of two formulations known to stick to engravings during production increased with a greater steepness of the cones' lateral face. With microencapsulated acetylsalicylic acid, no quantitative differences could be found between the adhesion forces obtained with plain and modified punch faces, indicating that the sticking behavior of the substance was not affected by shear forces. Starch 1500 showed higher adhesion force signals in comparison to those obtained with a plain punch face. Microcrystalline cellulose, which gave no adhesion force signals with a plain punch face and did not stick to the cones, showed distinct pull-off signals. The instrumented upper punch equipped with shear cones is a valuable instrument for detecting the adhesion caused by engravings and is therefore a helpful tool for tablet formulation development and the design optimization of tablet identification.

A novel method for the detection of sticking of tablets

The purpose of this work was to develop an instrumented upper punch to measure the adhesion force which occurs when the punch detaches itself from the upper surface of the tablet after compression. A specially designed adhesion force sensor instrumented with semiconductor strain gauges was inserted into an upper punch with a 25-mm punch face diameter suitable for a Korsch EK II eccentric press. Sorbitol, microencapsulated acetylsalicylic acid (ASA), and a formulation of a new active ingredient resulted in characteristic pull-off signals, providing a quantitative measure of the adhesion force. With "sticking-free" substances such as microcrystalline cellulose, tension signals could not be obtained; only Starch 1500 showed small adhesion force signals that indicated a sticking tendency. The compression force had a specific influence on the extent of the adhesion force; increasing the compression force caused an increase (sorbitol) or a decrease (ASA) of the adhesion force signals due to the plastic and elastic behavior of the substances. Depending on running time, ASA showed an increase in the adhesion force, reaching a plateau after 150 tablets. The addition of lubricants such as magnesium stearate resulted in smaller adhesion forces. The instrumented upper punch is a new helpful tool for the quantification of sticking and a valuable instrument in the development of formulations.

Docosahexaenoic acid ingestion inhibits natural killer cell activity and production of inflammatory mediators in young healthy men

The purpose of this study was to examine the effects of feeding docosahexaenoic acid (DHA) as triacylglycerol on the fatty acid composition, eicosanoid production, and select activities of human peripheral blood mononuclear cells (PBMNC). A 120-d study with 11 healthy men was conducted at the Metabolic Research Unit of Western Human Nutrition Reach Center. Four subjects (control group) were fed the stabilization diet throughout the study; the remaining seven subjects were fed the basal diet for the first 30 d, followed by 6 g DHA/d for the next 90 d. DHA replaced an equivalent amount of linoleic acid; the two diets were comparable in their total fat and all other nutrients. Both diets were supplemented with 20 mg D alpha-tocopherol acetate per day. PBMNC fatty acid composition and eicosanoid production were examined on day 30 and 113; immune cell functions were tested on day 22, 30, 78, 85, 106, and 113. DHA feeding increased its concentration from 2.3 to 7.4 wt% in the PBMNC total lipids, and decreased arachidonic acid concentration from 19.8 to 10.7 wt%. It also lowered prostaglandin E2 (PGE2) and leukotriene B4 (LTB4) production, in response to lipopolysaccharide, by 60-75%. Natural killer cell activity and in vitro secretion of interleukin-1beta and tumor necrosis factor alpha were significantly reduced by DHA feeding. These parameters remained unchanged in the subjects fed the control diet. B-cell functions as reported here and T-cell functions that we reported previously were not altered by DHA feeding. Our results show that inhibitory effects of DHA on immune cell functions varied with the cell type, and that the inhibitory effects are not mediated through increased production of PGE2 and LTB4.

Isolation, purity analysis and stability of hyperforin as a standard material from Hypericum perforatum L

In 1996 131.5 million daily doses of preparations containing extracts of Hypericum perforatum L. were prescribed in Germany for treating mild to moderately severe depressive disorders. New pharmacological and clinical results focus on hyperforin as the main active ingredient of the drug. Hyperforin (C35H52O4) is one of the main components (2-4%) of the dried herb Hypericum perforatum L. It was isolated after six consecutive steps: extraction of deep-frozen blossoms (-20 degrees C) with n-hexane by means of an Ultra Turrax at room temperature; separation of lipophilic substances on a silica gel column; purification of the relevant fraction by preparative HPLC; evaporation of the mobile phase under reduced pressure; removal of the remaining water by freeze-drying; and storage of hyperforin at -20 degrees C under nitrogen. The identity and purity of the isolated substance were determined by high-performance thin-layer chromatography (HPTLC), high-performance liquid chromatography (HPLC) with diode-array and ultraviolet detection (DAD and UV), Fourier-transformed infrared (FTIR) and proton nuclear magnetic resonance (1H NMR) spectroscopy, and liquid chromatography coupled with positive-ion electrospray-ionization tandem mass spectrometry (LC-ESI(+)-MS-MS). By use of these methods the purity of hyperforin was shown to be >99.9%. Peroxides present at each step of the isolation were detected by titration and by means of Merckoquant analytical peroxide test-strips. Elimination of the peroxides and stabilization of hyperforin was achieved by consistent protection from oxidation-the mobile phases were protected by use of ascorbic acid; evaporation and freeze-drying were performed under nitrogen; and the mobile phase used for preparative HPLC was sparged with helium. Stability testing was performed by HPLC-the samples were stored at -30 degrees C in a normal atmosphere and at -20, 4, and 20 degrees C in a normal atmosphere or under nitrogen. Results were compared with those obtained after storage under liquid nitrogen (-196 degrees C). Because of its high sensitivity to oxidation, hyperforin was more stable under nitrogen under all test conditions. There was no statistically significant difference between results obtained after 8 months at -20 degrees C under nitrogen or at -30 degrees C under a normal atmosphere and those from the reference sample stored under liquid nitrogen (-196 degrees C). Despite this, because of the tendency of hyperforin to degrade, long-term storage at -70 degrees C under nitrogen is recommended.

Investigation of the pellet-distribution in single tablets via image analysis

The influence of five different microcrystalline cellulose filler-binders on the pellet-distribution in tablets was investigated under production-scale conditions. Coloured coated pellets were tableted on an instrumented high speed rotary tablet press at four machine speed levels. The pellet-distribution on the upper and the lower tablet surfaces was detected via image analysis and correlated with the disintegration time and the crushing strength of the tablets. Filler-binders with a large surface area and a fibrous texture, like Avicel PH 101, enable the production of disintegrating tablets with an approximately homogeneous pellet-distribution within a large range of machine speeds, while pellet-containing tablets prepared with coarse microcrystalline cellulose granules showed an inhomogeneous pellet-distribution, depending on machine speed.

Surface acidity of solid pharmaceutical excipients III. Excipients for solid dosage forms

The surface acidities of pharmaceutical excipients are detected by color changes of acid-base indicators on the substrate's surface. To quantify the indicator's transition interval on the surface of hydrophilic excipients, as an organic solvent methanol is introduced for the preparation of indicator-excipient mixtures. The influence of the particle size on the determination of the surface acidity is investigated and particle size did not influence the determination within the particle size range investigated. Surface acidities of common excipients used in preparation of solid dosage forms are presented.

Optimization of an effervescent tablet formulation containing spray dried L-leucine and polyethylene glycol 6000 as lubricants using a central composite design

A rotatable central composite design is used to evaluate the effects of lubricants and compression force on the physical characteristics of effervescent tablets. Effervescent tablets lubricated with a combination of spray dried L-leucine and polyethylene glycol 6000 are prepared by direct compression and examined. Residual force, crushing strength and disintegration time are considered as response variables and related to the L-leucine and polyethylene glycol concentrations and to the compression force. The calculated models are used to assess the influence of the production factors on tablet properties. As increasing amounts of L-leucine, showing good lubricating properties, reduce the crushing strength and prolong tablet disintegration, the L-leucine concentration is kept at a low level. An optimum tablet formulation contains 2% L-leucine and 3% polyethylene glycol 6000. The tablets have a tensile strength of 0.47 MPa and disintegrate in less than 2 min. Predicted and experimental results are in agreement within a 95% CI.

The effect of dietary docosahexaenoic acid on plasma lipoproteins and tissue fatty acid composition in humans

Normal, healthy male volunteers (n = 6) were fed diets [high docosahexaenoic acid-DHA] containing 6 g/d of DHA for 90 d. The stabilization (low-DHA) diet contained less than 50 mg/d of DHA. A control group (n = 4) remained on the low-DHA diet for the duration of the study (120 d). Blood samples were drawn on study days 30 (end of the stabilization period), 75 (midpoint of the intervention period), and 120 (end of the intervention period). Adipose tissue (AT) samples were taken on days 30 and 120. The plasma cholesterol (C), low density lipoprotein (LDL)-C and apolipoproteins (apo) [Al, B, and lipoprotein (a)] were unchanged after 90 d, but the triglycerides (TAG) were reduced from a mean value of 76.67 +/- 24.32 to 63.83 +/- 16.99 mg/dL (n = 6, P < 0.007 using a paired t-test) and the high density lipoprotein (HDL)-C increased from 34.83 +/- 4.38 mg/dL to 37.83 +/- 3.32 mg/dL (n = 6, P < 0.017 using a paired t-test). The control group showed no significant reduction in plasma TAG levels. Apo-E, however, showed a marked increase in the volunteers' plasma after 90 d on the high-DHA diet, from 7.06 +/- 4.47 mg/dL on study day 30 to 12.01 +/- 4.96 mg/dL on study day 120 (P < 0.002 using a paired t-test). The control subjects showed no significant change in the apo-E in their plasma (8.46 +/- 2.90 on day 30 vs. 8.59 +/- 2.97 on day 120). The weight percentage of plasma DHA rose from 1.83 +/- 0.22 to 8.12 +/- 0.76 after 90 d on the high-DHA diet. Although these volunteers were eating a diet free of eicosapentaenoic acid (EPA), plasma EPA levels rose from 0.38 +/- 0.05 to 3.39 +/- 0.52 (wt%) after consuming the high-DHA diet. The fatty acid composition of plasma lipid fractions--cholesterol esters, TAG, and phospholipid--showed marked similarity in the enrichment of DHA, about 10%, after the subjects consumed the high-DHA diet. The DHA content of these plasma lipid fractions varied from less than 1% (TAG) to 3.5% (phospholipids) at baseline, study day 30. EPA also increased in all plasma lipid fractions after the subjects consumed the high-DHA diet. There were no changes in the plasma DHA or EPA levels in the control group. Consumption of DHA also caused an increase in AT levels of DHA, from 0.10 +/- 0.02 to 0.31 +/- 0.07 (wt%) (n = 6, P < 0.001 using a paired t-test), but the amount of EPA in their AT did not change. Thus, dietary DHA will lower plasma TAG without EPA, and DHA is retroconverted to EPA in significant amounts. Dietary DHA appears to enhance apo-E synthesis in the liver. It appears that DHA can be a safe and perhaps beneficial supplement to human diets.

The effect of dietary arachidonic acid on platelet function, platelet fatty acid composition, and blood coagulation in humans

Arachidonic acid (AA) is the precursor of thromboxane and prostacyclin, two of the most active compounds related to platelet function. The effect of dietary AA on platelet function in humans is not understood although a previous study suggested dietary AA might have adverse physiological consequences on platelet function. Here normal healthy male volunteers (n = 10) were fed diets containing 1.7 g/d of AA for 50 d. The control diet contained 210 mg/d of AA. Platelet aggregation in the platelet-rich plasma was determined using ADP, collagen, and AA. No statistical differences could be detected between the aggregation before and after consuming the high-AA diet. The prothrombin time, partial thromboplastin time, and the antithrombin III levels in the subjects were determined also. There were no statistically significant differences in these three parameters when the values were compared before and after they consumed the high-AA diet. The in vivo bleeding times also did not show a significant difference before and after the subjects consumed the high-AA diet. Platelets exhibited only small changes in their AA content during the AA feeding period. The results from this study on blood clotting parameters and in vitro platelet aggregation suggest that adding 1.5 g/d of dietary AA for 50 d to a typical Western diet containing about 200 mg of AA produces no observable physiological changes in blood coagulation and thrombotic tendencies in healthy, adult males compared to the unsupplemented diet. Thus, moderate intakes of foods high in AA have few effects on blood coagulation, platelet function, or platelet fatty acid composition.