1,720,956 research outputs found
Bilosomes as Soft Nanovesicular Carriers for Ropinirole Hydrochloride: Preparation and In- vitro Characterization
Get PDFBilosomes are nanovesicular carriers that contain bile salts and non-ionic surfactants in a bilayer with cholesterol. These are more ultra-deformable, elastic, and flexible than other nanovesicular carrier.
Ropinirole hydrochloride (RH) is a non-ergot dopamine D2-agonist. It is used to manage Parkinson's disease and to minimize "on-off" variations in levodopa responsiveness. The oral bioavailability is about 50% due to it being extensively metabolized in the liver, with an elimination half-life of about 6 h.
The aim of this study was to enhance oral drug delivery and provide the sustained release of RH by preparing it as soft nanovesicular carriers (bilosomes).
Eight formulas of RH bilosomes were prepared by a reverse-phase evaporation method using mixed surfactant (span®60: tween®60 at 1:2 ratio), cholesterol and sodium deoxycholate as bile salt.
All formulas were evaluated for their drug content, entrapment efficiency, vesicle size, polydispersity index, zeta potential, drug release, transmission electron microscopy and fourier transform infrared spectroscopy.
Results showed all prepared RH bilosomes were in nano-range with vesicle size ranging (from 124.40±10.60 to 294.60±11.50) nm, Zeta potential ranged (from -16.955±7.372 to -23.22±0.880) mV and with entrapment efficiency % ranged (from 57.30±6.48% to 77.77±3.78%).
The best formula F5 showed vesicle size (160.60±15.82) nm, Zeta potential (-20.75±0.930) mV, and entrapment efficiency %(77.77±3.78%) with 84.39% in-vitro release of RH after 24 h.
It is concluded that bilosomes are good nanovesicular carriers for enhancing oral drug delivery and providing the sustained release of RH and all that may enhance oral bioavailability for RH
Preparation and Evaluation of Telmisartan Solid Dispersion as Sublingual Tablets
Get PDFBackground: Telmisartan is an antihypertensive angiotensin II receptor antagonist drug commonly used to treat hypertension and renal disease. Based on the Biopharmaceutical Classification System. It’s a Class II poorly soluble drug.
Objective: To prepare a sublingual tablet by increasing the dissolution and solubility of Telmisartan utilizing the solid dispersion method.
Methods: Three methods were obtained to prepare the solid dispersion of telmisartan: solvent evaporation, Kneading, and microwave method. Each method uses surplus as a hydrophilic carrier in different ratios of 1%, 2%, and 3%. Preparation of ternary solid dispersion by adding potassium carbonate salt to the binary solid dispersion. After that preparing the sublingual tablets by applying a direct compression method, using different types and ratios of superdisintegrants such as crospovidone, croscarmellose and sodium starch glycolate in 5% and 10%.
Study the evaluation tests of sublingual tablets, such as friability, hardness, disintegration time and dissolution time.
Results: The solid dispersion showed an improvement in solubility over the pure medication. The best result was obtained with the formula (Telmisartan, soluplus and k2co3 salt at 1:1:0.3 ratio) prepared by microwave method, in this method and the high ratio of soluplus, the solubility increased more than the solvent evaporation and kneading method. The selected tablet is prepared using crospovidone 10% as a superdisintegrant that appears disintegration time in 5 seconds and releases in 1 min in dissolution media.
Conclusion: The solubility and dissolution of Telmisartan were improved by microwave-based ternary solid dispersion using hydrophilic carriers and salt in a ratio of 1:1:0.3 (drug: carrier: salt). The analysis exerts the increases in wettability, enhanced solubility, and dissolution due to conversion from crystal to amorphous state.
Received May. 2023
Accepted Aug. 2023
Published Jan. 2024
Preparation, In-vitro, and Ex-vivo Evaluation of Ondansetron Loaded Invasomes for Transdermal Delivery
Get PDFInvasomes are newly developed types of nanovesicles. A vesicular drug delivery system is considered one of the approaches for transdermal delivery to enhance permeation and improve drug bioavailability. Ondansetron is a serotonin receptor antagonist used for treating vomiting associated with different clinical cases. The study aimed to prepare invasomal dispersions for improving permeation of ondansetron across the skin with a controlled release pattern. Twenty-seven formulas of ondansetron-loaded invasomes were prepared by a modified mechanical dispersion method. These formulas were optimized by studying the effect of variables on entrapment efficiency. Vesicle size, polydispersity, zeta potential, in-vitro release and ex-vivo permeation studies were done for the optimized formulas. The selected formula was )F25( had )88.24%±0.04 (entrapment, (317.7 nm) vesicle size, (0.29) polydispersity, and (-31.5mV) zeta potential. In-vitro release study showed That (F25) had 75% release after (12) hrs., and dissolution followed the Korsmeyer-Peppas model with anomalous diffusion. Ex-vivo permeation study showed steady-state flux was 340.2 µg/cm2.hr with no lag time using rat skin tissue. A transmission electron microscope was done to visualize the selected formula. Invasomes are considered promising drug delivery systems for transdermal delivery of ondansetron, ensuring efficient permeation with a sustained release pattern
Preparation and characterization of vemurafenib microemulsion
Get PDFHuman melanoma is the most common and malignant type of skin cancer. Vemurafenib has been used for the treatment of malignant or metastatic melanoma. Oral vemurafenib has serious adverse drug reactions including
QTc sigment prolongation of heart ECG that may result in discontinuation of treatment. The aim of study was to prepare o/w vemurafenib microemulsion to be used for topical administration. Saturated solubility of vemurafenib were performed in different oils, surfactants and co-surfactants. Peppermint oil, Tween 20 and PEG 400 were chosen to be the oil phase, surfactant and co-surfactant repectively. Since, vemurafenib had the highest solubility in these materials. Six fromulas (F1- F6) of vemurafenib microemulsion were prepared by simple titration method and characterized for their particle size, polydipersity (PDI), zeta potential, microemulsion morphology, dilution test, conductivity, thermodynamic stability and drug release. Formula F3 was chosen since it exhibits the lowest particle size (11.83 nm ± 0.55 nm), zeta potential -2.57 mV, passed the thermodynamic stability tests and had significantly higher (P < 0.05) release percent for vemurafenib (91% within 24 h). As a conclusion, microemulsion is considered as a poweful and promising drug delivery system for topical administatio
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
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