1,720,961 research outputs found
PREPARATION AND CHARACTERIZATION OF GRAPEFRUIT OIL BASE MICROEMULSIONS OF CAFFEINE
Get PDFObjective: The objective of the present work was to prepare and characterize grapefruit oil base microemulsions loaded with caffeine as a model hydrophilic compound.
Methods: The formulation ingredients were selected based on surfactant efficiency and solubility studies. Ternary phase diagrams of grapefruit oil were constructed using the water titration method. Nine O/W microemulsions were constructed and prepared by mixing surfactant system, grapefruit oil, water and caffeine together. The resulting microemulsions were investigated for viscosity using Brookfield viscometer, for pH value using a digital pH meter, and for average particle size and polydispersity index (PDI) using a Zetasizer Nano. Ex vivo skin permeation through porcine ear skin was conducted using a side-by-side diffusion cell. The amount of caffeine was analyzed using HPLC-UV method.
Results: Tween 20 yielded the highest emulsification ability for grapefruit oil and the highest caffeine solubility. It was selected as a major surfactant. Caffeine was slightly soluble in ethanol and isopropyl alcohol, but sparingly soluble in propylene glycol (PG). These ingredients were used as the cosurfactants. Nine grapefruit oil base microemulsions were prepared and characterized. The pH of microemulsions was within the range of 4.48-5.96. Particle size was in the range of 10.81±0.03 to 62.18±21.04 µm with the PDI of 0.13±0.02 to 0.64±0.11. Viscosity and particle size of microemulsions increased significantly with increasing grapefruit oil or tween 20 content. Addition of PG as cosurfactant resulted in the increases of viscosity, particle size and PDI. Depending on the formulation parameters, the permeation fluxes of caffeine from grapefruit oil base microemulsions were in the range of 28.4±3.4-361.4±15.2 µg/cm2/h.
Conclusion: The grapefruit oil base microemulsions were successfully formulated. The physical properties and caffeine permeation of these microemulsions were found to be dependent on the grapefruit oil content, tween 20 content, cosurfactant type and content, as well as caffeine loading. The optimal formulation of grapefruit oil base microemulsion suggested composition of 5% grapefruit oil, 50% surfactant system (tween 20 and ethanol at the ratio of 9:1), and water
DEVELOPMENT OF HERBAL CAPSULES CONTAINING MULBERRY LEAF AND BLACK TEA EXTRACTS USING THE MODIFIED LIQUISOLID TECHNIQUES
Get PDFObjective: The objective of this study was to develop the capsules containing mulberry leaf extract (MLE) and black tea extract (BTE).
Methods: MLE and BTE were prepared by maceration and determined for phytochemicals, in vitro alpha-amylase and alpha-glucosidase inhibitory activities using the enzymatic colorimetric assay. The granules of MLE and BTE were prepared by the application of liquisolid technique and evaluated for the flow properties. The selected granule formulation was filled into the hard gelatin capsule and evaluated for weight variation and disintegration.
Results: The yields of MLE and BTE solid extracts were 8.12 and 4.23% w/w, respectively. Total phenolic and total flavonoid contents were 32.46±5.22 mg TAE/g DW and 44.03±3.37 mg QE/g DW for MLE and 244.66±23.28 mg TAE/g DW and 214.43±3.22 mg QE/g DW for BTE, respectively. The IC50 for alpha-amylase of MLE and BTE were 0.69±0.04 and 3.34±0.08 mg/ml, respectively; whereas those for alpha-glucosidase of MLE and BTE were 0.67±0.42 and 0.43±0.15 mg/ml, respectively. The granule prepared with MCC and silica at the ratio of 20:1 showed the highest flowability. The weight variation of the prepared MLE and BTE capsules was within the range of the limitation criteria of ±5%. The average disintegration time of capsules was 1.1±0.1 min.
Conclusion: Herbal capsules of MLE and BTE were successfully prepared. The suitable carrier and coating were MCC and silica with a ratio of 20:1. This study revealed the potential application of liquisolid technique as a tool to produce a capsule of herbal crude extracts
EFFECTS OF FORMULATION PARAMETERS ON PROPERTIES OF GASTRIC FLOATING TABLETS CONTAINING POORLY SOLUBLE DRUG: DICLOFENAC SODIUM
Get PDFObjective: The objective of this study was to prepare and investigate the effects of formulation parameters on the properties of gastric floating tablets containing diclofenac sodium (DICL) as a model of poorly soluble acidic drug, sodium bicarbonate (NaHCO3) or calcium carbonate (CaCO3) as gas-forming agent, hydroxypropyl methylcellulose (HPMC) K100M or K15M as swelling polymer and sodium lauryl sulfate (SLS) as wetting agent.Methods: DICL floating tablets were prepared using direct compression method. The compressed tablets were evaluated for tablet properties, swelling index, and in vitro buoyancy. The in vitro release under non-sink condition was determined. Molecular interaction was studied using differential scanning calorimetry and fourier transform infrared spectroscopy.Results: The tablet properties of all DICL floating tablets were within the acceptance criteria. The molecular interaction between DICL and excipients in the formulation was excluded. Depends on the formulation compositions, the swelling index at 3 h (SI) ranged from 44±11 to 1158±33 %, whereas the buoyancy properties namely floating lag time (FLT) and total floating time (TFT) were 0.33±0.03 to 10.04±0.04 min and 10.0±0.0 to>12 h, respectively. NaHCO3 showed higher swelling, buoyancy and release properties compared to those of CaCO3. NaHCO3 at 20% gave sufficient swelling (SI of 1074±16 %), buoyancy (FLT of 0.39±0.03 min, TFT of>12 h) and release properties (cumulative release of 5.83±0.02 %). HPMC K100M showed better swelling property of which its initial swelling rate was 1412±25 %/h compared to HPMC K15M (1042±31 %/h). HPMC K100M at 20% showed better buoyancy and release properties compared to those obtained from HPMC K100M at 30%. The release testing under non-sink conditions was able to distinguish the effect of formulation parameters on the DICL release profiles. Incorporation of SLS at 0.25% could enhance both release rate and cumulative release of DICL from the floating tablets. Nevertheless, it showed the unacceptable adverse effect on swelling and buoyancy properties of DICL floating tablets. The TFT of DICL floating tablets containing 0.25% SLS was only 0.5±0.0 h.Conclusion: DICL floating tablets were successfully prepared. Tablets possessing suitable swelling and buoyancy properties were obtained using NaHCO3 at 20% as a gas-forming agent, with HPMC K100M at 10 and 20% as floating matrix and swelling polymer. Addition of SLS as wetting and solubilizing agent showed the unacceptable adverse effect on the swelling and buoyancy properties of DICL floating tablets. The release under sink conditions and/or in vivo pharmacokinetic studies shall be further performed
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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