Search results for "Dissolution"
showing 10 items of 333 documents
Los efectos directos y colaterales de la disolución de Herri Batasuna
2005
Alexandre.Catala@uv.es La ilegalización de Herri Batasuna, Euskal Herritarrok y Batasuna (Sentencia del Tribunal Supremo de 27 de marzo de 2003) comportó una serie de consecuencias que son analizadas en el presente trabajo. En primer lugar, la estrategia de presentar en sucesivos comicios (elecciones municipales y autonómicas de 2003, elecciones al Parlamento Europeo de 2004 y elecciones al Parlamento vasco de 2005) agrupaciones electorales que no eran más que continuación de aquéllos con la clara intención de burlar la aplicación de la Ley Orgánica de Partidos Políticos y perpetuar así su actividad. En segundo lugar, la polémica sobre la disolución del grupo parlamentario correspondiente e…
Automated simultaneous triple dissolution profiles of two drugs, sulphamethoxazole-trimethoprim and hydrochlorothiazide-captopril in solid oral dosag…
2003
This article deals with the simultaneous determination of three dissolution profiles with the aid of the new and emerging continuous-flow methodology known as multicommutation. This methodology is based on a flow network of a set of solenoid valves controlled by the computer and acting as independent multicommutators to allow the easy and automated control of flowing solutions. The obtained three dissolution profiles from one dosage form are the whole formulation profile or "global profile" recommended by pharmacopoeias, and, at same time, are recorded two "individual" profiles from two drugs present in the formulation. This is the second attempt to obtain simultaneously three dissolution p…
Defining level A IVIVC dissolution specifications based on individual in vitro dissolution profiles of a controlled release formulation.
2018
Regulatory guidelines recommend that, when a level A IVIVC is established, dissolution specification should be established using averaged data and the maximum difference between AUC and Cmax between the reference and test formulations cannot be greater than 20%. However, averaging data assumes a loss of information and may reflect a bias in the results. The objective of the current work is to present a new approach to establish dissolution specifications using a new methodology (individual approach) instead of average data (classical approach). Different scenarios were established based on the relationship between in vitro-in vivo dissolution rate coefficient using a level A IVIVC of a cont…
Integrating theoretical and experimental permeability estimations for provisional biopharmaceutical classification: Application to the WHO essential …
2018
The accuracy of the provisional estimation of the Biopharmaceutics Classification System (BCS) is heavily influenced by the permeability measurement. In this study, several theoretical and experimental models currently employed for BCS permeability classification have been analysed. The experimental models included the in situ rat intestinal perfusion, the ex vivo rat intestinal tissue in an Ussing chamber, the MDCK and Caco-2 cell monolayers, and the parallel artificial membrane (PAMPA). The theoretical models included the octanol-water partition coefficient and the QSPeR (Quantitative Structure-Permeability Relationship) model recently developed. For model validation, a dataset of 43 comp…
Validation of Dissolution Testing with Biorelevant Media: An OrBiTo Study.
2017
Dissolution testing with biorelevant media has become widespread in the pharmaceutical industry as a means of better understanding how drugs and formulations behave in the gastrointestinal tract. Until now, however, there have been few attempts to gauge the reproducibility of results obtained with these methods. The aim of this study was to determine the interlaboratory reproducibility of biorelevant dissolution testing, using the paddle apparatus (USP 2). Thirteen industrial and three academic laboratories participated in this study. All laboratories were provided with standard protocols for running the tests: dissolution in FaSSGF to simulate release in the stomach, dissolution in a singl…
Controlling the cohesion of cement paste
2005
The main source of cohesion in cement paste is the nanoparticles of calcium silicate hydrate (C-S-H), which are formed upon the dissolution of the original tricalcium silicate (C(3)S). The interaction between highly charged C-S-H particles in the presence of divalent calcium counterions is strongly attractive because of ion-ion correlations and a negligible entropic repulsion. Traditional double-layer theory based on the Poisson-Boltzmann equation becomes qualitatively incorrect in these systems. Monte Carlo (MC) simulations in the framework of the primitive model of electrolyte solution is then an alternative, where ion-ion correlations are properly included. In addition to divalent calciu…
Electrochemical characterization of iron sites in ex-framework FeZSM-5
2002
Abstract The electrochemical response of FeZSM-5 prepared by an ex-framework method has been studied using Paraloid B72 polymer film electrodes immersed in aqueous media using H2SO4, HCl, Na2EDTA and NaCl electrolytes. The ex-framework method comprises the hydrothermal synthesis of isomorphously substituted FeZSM-5, followed by calcination at 823 K and subsequent steam treatment (300 mbar H2O in N2) at 873 K. During this process iron is extracted to extra-framework positions. Also partial dealumination of the zeolite framework takes place. Characteristic voltammetric responses in the +1.0 to −0.6 V versus SCE potential range have been recorded and were used to characterize the iron species …
Ionic Liquids: Media for Better Molecular Catalysis
2004
Ionic liquids (ILs) are more and more suggested as substitutes for traditional solvents in organic synthesis and catalysis. They are suitable candidates for the dissolution of ionic complexes. They can activate and retain them in a polar state: in fact, they act as sequestrands, opening the route to two-phase processes and easier catalyst recovery. This paper reviews authors' results with the development of new syntheses of ILs and applications in carbon–carbon bond formation (dimerisation of methyl acrylate) and redistribution (ring closing metathesis) reactions using ionic precatalysts.
Dissolution‐corrosion measurements with limestone and gypsum tablets in active sulphuric acid caves of southern Italy
2022
Dissolution‐corrosion (DC) represents an important factor for speleogenesis, and can be measured monitoring weight variation over time of carbonate and gypsum tablets exposed in underground environments. The oxidation of H2S produces H2SO4, which in carbonate host rock induces the surface of carbonate tablets to be rapidly corroded by sulphuric acid, whereby CaCO3 is replaced by CaSO4∙2H2O, producing a significant weight gain. We describe preliminary results of DC monitoring in four still‐active SAS systems, including Ninfe Cave and Terme Sibarite (Calabria), Fetida Cave (Apulia), and Acqua Fitusa Spring Cave (Sicily). The tablets have been set inside the caves, in three different condition…
Influence of cryogenic grinding on properties of a self-emulsifying formulation
2003
Abstract Recently, self-emulsifying drug delivery systems (SEDDS) have been developed as a method to deliver lipophilic drugs. Gelucire® 44/14 is an excipient, from the lauroyl macrogolglycerides family, producing a fine oil-in-water emulsion when introduced into an aqueous phase under gentle agitation as SEDDS, improving thereby solubility of poorly water-soluble drugs and their bioavailability. The aims of this study were to process Gelucire® 44/14 into a powder by cryogenic grinding to produce solid oral dosage forms and to investigate influence of this process on different properties of a formulation made of Gelucire® 44/14 and ketoprofen (90/10). Cryogenic grinding produced Gelucire® 4…