1,720,960 research outputs found
Alginate-prednisolone controlled delivery systems: design and in vitro characterization
No full textPurpose. The current study aimed to develop a controlled release formulation for the oral
administration of prednisolone (P), potentially useful for the treatment of chronic inflammatory
diseases.
Methods. Prilling was selected as micro-encapsulation technique to produce drug loaded
hydrophilic microparticles (gel-beads). The influence of process parameters such as composition
and viscosity of the aqueous feed solutions (sodium alginate 2.0-2.75% w/v in different ratio with
P 1:10-1:4), aqueous bulks for ionotropic gelation and cross-linking time (5-10 min) on the
obtained particles was evaluated. Beads morphology, size and solid state characteristics were
analysed (SEM microscopy, FTIR, DSC). In vitro release study was assessed in conditions
simulating the gastrointestinal environment (USP XXVII).
Results. Particles morphology as well as release kinetics of alginate formulations were strongly
related to the amount of alginate and P loaded into the feed solutions. Best results were
obtained increasing alginate and P content in order to achieve a compact polymeric matrix able
to better retain the drug. The best formulation, F6 released around 20% of P in simulated gastric
fluid (SGF, pH=1); complete drug release is achieved after pH change in simulated intestinal fluid
(SIF, pH=6.8) in about 3.5 h. This behavior may be explained by a combination of alginate pHdependent
solubility, cross-linking properties of Zn2+ and polymeric matrix density in #F6; beads
did not swell or erode in SGF and still keep intact matrix, whereas in SIF (at pH 6.8) they started
to swell and further erode due to the ion-exchange. Moreover, in order to further improve the
release kinetic, the formulation F6 has been insert into suitable capsules able to protect the drug
in acidic medium and to extend anti-inflammatory activity.
Conclusions. Conventional therapies of chronic inflammatory diseases (such as arthritis
arthrosis) consists of multiple daily administrations of prednisolone leading to a variable drug
blood level and ineffective therapy. This study suggested that prilling is an appropriate
technological approach to manufacture drug delivery systems able to control prednisolone
release. The best formulation F6 could be proposed as self-consistent formulation or as a dosage
form hosted into suitable capsules for the treatment of inflammatory chronic diseases
Design and In Vivo Anti-Inflammatory Effect of Ketoprofen Delayed Delivery Systems
No full textFor the treatment of inflammatory-based diseases affected by circadian rhythms, the development of once-daily dosage forms is required to target early morning symptoms. In this study, Zn-alginate beads containing ketoprofen (K) were developed by a tandem technique prilling/ionotropic gelation. The effect of main critical variables on particles micromeritics, inner structure as well as on drug loading and in vitro drug release was studied. The in vivo anti-inflammatory efficacy was evaluated using a modified protocol of carrageenan-induced edema in rat paw administering beads to rats by oral gavage at 0, 3, or 5 h before edema induction. Good drug loading and desired particle size and morphology were obtained for the optimized formulation F20. In vitro dissolution studies showed that F20 had a gastroresistant behavior and delayed release of the drug in simulated intestinal fluid. The in vitro delayed release pattern was clearly reflected in the prolonged anti-inflammatory effect in vivo of F20, compared to pure ketoprofen; F20, administered 3 h before edema induction, showed a significant anti-inflammatory activity, reducing maximum paw volume in response to carrageenan injection, whereas no response was observed for ketoprofen. The designed beads appear a promising platform suitable for a delayed release of anti-inflammatory drugs. © 2015 Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci 104:3451-3458, 2015
A novel core-shell chronotherapeutic system for the oral administration of ketoprofen
No full textThe aim of a chronotherapeutic medicine is to tailor drug in vivo availability to circadian rhythms of diseases in order to reduce side effects and improve patient compliance. To counteract morning symptoms of early morning pathologies, a drug delivery system able to delay ketoprofen release after oral administration has been proposed. Particles made of a pectin matrix were produced by means of prilling; core-shell systems were produced covering the drug particles with Eudragit S100®. The systems developed, containing different drug/polymer ratios, were fully characterized in terms of drug content, efficiency of encapsulation, morphology and drug release kinetics. The results indicated that the loading of larger amounts of drug in the feed solution led to spherical and mono-disperse beads, with high encapsulation efficiency and a reduced drug delivery in gastric simulated fluids (22%). Finally, a further delay of drug release (7.3% released in simulated gastric fluid) was achieved applying to the drug/pectin core a shell of Eudragit S100® (40% w/w) a gastro-resistant polymer. This core-shell platform exploits the different characteristics of the two selected polymers, i.e. pH dependent solubility of Eudragit S100® and the peculiarities of pectin, degraded slowly in alkaline environment and selectively by the intestinal microflora in vivo
Natural polysaccharides platforms for oral controlled release of ketoprofen lysine salt
No full textContext: Ketoprofen lysinate (KL) is one of the most widely used non-steroidal anti-inflammatory drugs in the symptomatic treatment of some chronic inflammatory diseases. Compared to ketoprofen, KL shows better pharmacokinetics and tolerability. However, due to its short half-life of 1–2 h, a multiple dose regimen is required for oral administration. Thus, the present work deals with its encapsulation in a hydrogel-based system by prilling in order to prolong its activity. Objective: In this paper, we propose alginate and pectin as carriers and release tailoring agent for the development of hydrogel-based beads for KL retarded and sustained release. Materials and methods: Beads were produced by a Nisco Encapsulator® using alginate or pectin. Operative variables were optimized to produce beads with desired morphology and size. Solid state properties were analyzed by SEM and DSC. Drug release performance was studied by Pharmacopeia pH-change assay to simulate gastrointestinal environment. Results and discussion: Prilling technique was successfully used to encapsulate high soluble drugs as KL in polysaccharides-based hydrogels. Pectin proved to be a proper polymer able to encapsulate ketoprofen lysine salt. Formulation (F8) showed good morphological properties and size, high drug content (15.6%) and encapsulation efficiency (93.5%) and promising drug release profiles. Hosting F8 in an acid-resistant capsule (DR®caps) a delivery platform has been developed to control KL release in a delayed (90 min lag time) and prolonged way (270 min complete release). Conclusion: The platform may be proposed as potentially useful in the oral administration of NSAIDs in chronic inflammatory diseases affected by circadian rhythm
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Full text link“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
Full text linkWe 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
Full text linkWe 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
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