124 research outputs found
Controlled release from directly compressible theophylline buccal tablets
No full textThe aim of the current study was the development of theophylline buccal adhesive tablets using direct compression. Buccal adhesive formulations were developed using a water soluble resin with various combinations of mucoadhesive polymers. The prepared theophylline tablets were evaluated for tensile strength, swelling capacity and ex vivo mucoadhesion performance. Ex vivo mucoadhesion was assessed using porcine gingival tissue and the peak detachment forces were found to be suitable for a buccal adhesive tablet with a maximum of 1.5N approximately. The effect of formulation composition on the release pattern was also investigated. Most formulations showed theophylline controlled release profiles depended on the grade and polymer ratio. The release mechanisms were found to fit Peppas' kinetic model over a period of 5h. In general the majority of the developed formulations presented suitable adhesion and controlled drug release. Copyright © 2010 Elsevier B.V. All rights reserved
Preparation and optimization of PMAA–chitosan–PEG nanoparticles for oral drug delivery
No full textThe objective of this study was to develop pH sensitive polymethacrylic acid–chitosan–polyethylene glycol (PCP) nanoparticles. This was achieved by dispersion polymerization of methacrylic acid (MAA), polyethylene glycol (PEG) and different chitosan (CS) grades in the presence of cross linking agent ethylene dimethacrylate (EDMA) and polymer initiator potassium persulphate. Method development was carried out by varying formulation parameters such as type of CS, ratio of PEG to CS, quantity of solvent and polymer initiator. Metoprolol (MTP) tartrate was incorporated into the nanoparticles (NPs) as a model drug. Laser diffraction, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) studies revealed that the NPs were spherical with smooth surfaces ranging in size from 190 to 450 nm. X-ray diffraction (XRD) and differential scanning calorimetry (DSC) findings showed the presence of amorphous MTP in PCP NPs. The MTP loading of PCP and glycol chitosan (GC) NPs varied from 10 to 45% depending on the CS grade while both types of NPs showed excellent binding efficiency on mucin from porcine stomach. The in vitro dissolution study showed pH dependent release profiles suggesting that the PCP NPs system have great potential for oral controlled drug delivery as an alternative to conventional dosage forms
Dionysios Scytobrachion (32)
No full textNew edition, with translation and commentary, of Dionysios Skytobrachion (FGrHist/BNJ2 32; updated from the 1st edition by a different author
Dionysios Ps.-Areiopagites im heutigen Forschungsgespräch
No full textThe intention of this paper is to overcome an alarming polarization within the actual academic debate on the writing of the unknown author of the Corpus Areopagiticum. It discusses five exemplary problems: a. unity and diversity in God; b. theurgy in Proklos and Ps.-Dionysios; c. Porphyry, Dionysios and the “anthropological Model” for the solution of the Christological problem; d. ambivalences within the Dionysian corpus; e. the intention of the author. In the introduction the paper also touches – very briefly, it is true – upon the question, if Peter the Iberian could have been the author of that corpus, as – independently from each other – E. Honigmann and S. Nutsubidze once proposed
Development and evaluation of Cetirizine HCl taste-masked oral disintegrating tablets
No full textThe purpose of the current study was to mask the taste of cetirizine HCl and to incorporate the granules produced in oral disintegrating tablets (ODT). The bitter, active substance was coated by fluidized bed coating using Eudragit® RL30-D at levels between 15% and 40% w/w. The ODTs were developed by varying the ratio of superdisintegrants such as sodium croscarmellose, crospovidone grades and low substituted hydroxypropyl cellulose (L-HPC). A direct compression process was used to compress the ODTs under various compaction forces to optimize tablet robustness. The properties of the compressed tablets including porosity, hardness, friability and dissolution profiles were further investigated. The in vitro and in vivo evaluation of the tablet disintegration times showed almost identical rapid disintegration below 10 s at the optimal levels of each superdisintegrant. Finally, the taste and sensory evaluation in human volunteers demonstrated excellence in masking the bitter active and tablet palatability
Development and release mechanism of diltiazem HCl prolonged release matrix tablets
No full textA coated matrix tablet formulation has been used to develop controlled release diltiazem HCl (DIL) tablets. The developed drug delivery system provided prolonged drug release rates over a defined period of time. DIL tablets prepared using dry mixing and direct compression and the core consisted of hydrophilic and hydrophobic polymers such as hydroxypropylmethylcellulose (HPMC), Eudragits RLPO/RSPO, microcrystalline cellulose, and lactose. Tablets were coated with Eudragit NE 30D, and the influence of varying the inert hydrophobic polymers and the amount of the coating polymer were investigated. The release profile of the developed formulation was described by the Higuchi model. Stability trials up to 6 months displayed excellent reproducibility
Using a modified shepards method for optimization of a nanoparticulate cyclosporine a formulation prepared by a static mixer technique
No full textAn innovative methodology has been used for the formulation development of Cyclosporine A (CyA) nanoparticles. In the present study the static mixer technique, which is a novel method for producing nanoparticles, was employed. The formulation optimum was calculated by the modified Shepard's method (MSM), an advanced data analysis technique not adopted so far in pharmaceutical applications. Controlled precipitation was achieved injecting the organic CyA solution rapidly into an aqueous protective solution by means of a static mixer. Furthermore the computer based MSM was implemented for data analysis, visualization, and application development. For the optimization studies, the gelatin/lipoid S75 amounts and the organic/aqueous phase were selected as independent variables while the obtained particle size as a dependent variable. The optimum predicted formulation was characterized by cryo-TEM microscopy, particle size measurements, stability, and in vitro release. The produced nanoparticles contain drug in amorphous state and decreased amounts of stabilizing agents. The dissolution rate of the lyophilized powder was significantly enhanced in the first 2 h. MSM was proved capable to interpret in detail and to predict with high accuracy the optimum formulation. The mixer technique was proved capable to develop CyA nanoparticulate formulations
Hymn to Liberty
No full textTitle: Ὕµνος εἰς τὴν Ἐλευθερίαν (Hymn to Liberty) Originally published: In the appendix to the second volume of Claude Fauriel’s Chants populaires de la Grèce Moderne (Paris: Didot, 1825). In the same year another version was published in Messolongi, together with an Italian translation. Language: Greek The modern critical edition is Dionysios Solomos, παντα, v. 1. Ποιήµατα (Athens: Ικαρος, 1979), p. 71. About the author Dionysios Solomos [1798, Zante (Gr. Zakynthos) – 1857, Corfu (Gr. Kerkyr..
Development of hot-melt extrusion as a novel technique for the formulation of oral solid dosage forms
No full textHot-melt extrusion (HME) is one of the most widely used technologies in the plastic, rubber and food industries and it has also been extensively explored and used in academia and the pharmaceutical industry over the last decade. This project aims to investigate the efficiency of hydrophilic polymers to enhance the dissolution rate of poorly water-soluble APIs processed by HME. Indomethacin (INM) and famotidine (FMT) were selected as model active substances while polyvinyl caprolactam graft copolymer, Soluplus® (SOL) and vinylpyrrolidone-vinyl acetate copolymer grades Kollidon® VA64 (VA64) and Plasdone® S630 (S630) were used as hydrophilic polymeric carriers. For the purpose of the study, all drug-polymer binary blends at various ratios were processed by a Randcastle single screw extruder. The physico-chemical properties and the morphology of the extrudates were evaluated via x-ray powder diffraction (XRPD), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). INM and FMT exhibited strong plasticization effects at specific concentrations and were found to be molecularly dispersed within the polymer blends. The in vitro dissolution studies showed increased INM/FMT release rates for all formulations compared to that of pure APIs alone. Ibuprofen was also embedded in a methacrylate copolymer (Eudragit® EPO) matrix to produce solid dispersions by hot-melt extrusion processing. The obtained granules were incorporated into orally disintegrating tablets (ODTs). The tablets were developed by varying the ratio of superdisintegrants such as sodium croscarmellose and cross-linked polyvinylpyrrolidone while a direct compression process was used to compress the ODTs under various compaction forces to optimize tablet robustness. The properties of the compressed tablets which included porosity, hardness, and friability and dissolution profiles were further evaluated and compared with commercially available Nurofen® Meltlet ODTs. In vitro dissolution of the extruded ODTs showed rapid release of ibuprofen compared to that of Nurofen® Meltlets. The in vitro and in vivo evaluation of the masking efficiency of hot melt extruded paracetamol (PMOL) formulations was examined. Extruded granules containing high PMOL loadings in Eudragit EPO® (EPO) or Kollidon® VA64 (VA64) were prepared by HME. Similarly propranolol HCl (PRP), diphenhydramine HCl (DPD), cetirizine HCl (CTZ) and verapamil HCl (VRP) were used as model cationic active substances while pH sensitive anionic methacrylic acid based methyl methacrylate coplolymers Eudragit® L100 (L100) and ethyl acrylate copolymer Eudragit® L100-55 (Acryl-EZE®) (L100-55) were used as polymeric carriers in order to produce taste masked extruded formulations determining drug-polymers intermolecular interactions. The taste masking effect of the processed formulation was evaluated in vivo by a panel of six healthy human volunteers. In addition, in vitro evaluation was carried out by an Astree e-tongue (Alpha MOS) equipped with seven sensors and Taste Sensing System TS5000Z (INSENT), respectively.
The taste and sensory evaluation in human volunteers demonstrated that the formulation masked the bitter taste of the APIs and improved tablet palatability. In addition to that the taste sensing technology demonstrated taste improvement for all polymers by correlating the data obtained for the placebo polymers and the pure APIs alone. The e-tongue results were in good agreement with the in vivo evaluation. Molecular modelling (Gaussian 09) predicted the existence of two possible H-bonding types while Fourier Transform Infra-Red (FT-IR) and NMR studies confirmed drug-polymer interactions between the functional groups of both components (cationic drugs–anionic polymers). Furthermore, the intermolecular interactions evaluated by Flory-Huggins interaction parameters theory and X-ray photoelectron spectroscopy (XPS) showed stronger interactions between drug-polymer in L100 systems compared to that of L100-55 systems. The mechanism of the intermolecular interactions derived from this research showed the presence of H bonding between the amine group of the active substances and the carboxylic groups in the polymer.
Hydrocortisone (HCS) was also embedded and extruded with ethyl cellulose N10 (EC N10) or ethyl cellulose Premium 7 (EC P7) in order to develop sustained release tablets processed by HME. The compressed tablets were subsequently coated with an enteric coating polymer, Eudragit® S100 (15-20%), which showed sustained release over 12 hrs with a lag time of 2 hrs. Further analysis of the release mechanism of HCS from tablets was performed by implementing five different kinetic release models which confirmed that the release of HCS from both coated and uncoated tablets followed a first order kinetic model
Hypatios of Ephesos and Ps.-Dionysios Areopagites
No full textThis article demonstrates, first, that Hypatios of Ephesos did not consider all the writings of Ps.-Dionysios the Areopagite to be forgeries, but only those citations from this author which the Syrian Orthodox (‘Severan’) bishops offered in support of their claims during the Collatio cum Severianis in 532. It then argues that Hypatios’ text Περὶ τῶν ἐν τοῖς ἁγίοις οἴκοις, preserved in Cod. par. gr. 1115, should be considered an important testimony to the pre-Iconoclast reception of Ps.-Dionysios’ doctrine of images (in the sense of Biblical and liturgical symbols). Finally, it shows that this text was altered during the Iconoclast period in an attempt to use the statements that originally were not meant to refer to painted images (icons) in the new polemical context but was ultimately discarded because the arguments it contains appeared unsatisfactory both to the Iconoclasts and Iconophile
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