Search results for "Dissolution"
showing 10 items of 333 documents
Influence of poloxamers on the dissolution performance and stability of controlled-release formulations containing Precirol® ATO 5
2005
Abstract Lipid excipients are usually used for the development of sustained-release formulations. When used in relatively high quantities, Precirol ® ATO 5 imparts sustained-release properties to solid oral dosage forms, by forming a lipid matrix. To control or adjust the drug release kinetics from such lipid matrix however, one must often resort to complementary ingredients or techniques. This study investigates the influence of poloxamers (Lutrol ® ) included in lipid matrices composed of glyceryl palmitostearate (Precirol ® ATO 5) on their dissolution performance and their stability. The addition of these hydrophilic polymers in the lipid matrix increased the amount of theophylline relea…
Mechanistic investigation of food effect on disintegration and dissolution of BCS class III compound solid formulations: the importance of viscosity
2012
A negative food effect, i.e. a decrease in bioavailability upon the co-administration of compounds together with food, has been attributed particularly with high solubility/low permeability compounds (BCS class III). Different mechanisms have been proposed including intestinal dilution leading to a lower concentration gradient across the intestinal wall as well as binding of the active pharmaceutical ingredient to food components in the intestine and thereby decreasing the fraction of the dose available for absorption. These mechanisms refer primarily to the compound and not to the dosage form. An increase in viscosity of the dissolution fluid will in particular affect the absorption of BCS…
Preparation and Biological Evaluation of Ethylcellulose Microspheres Containing Tolmetin
1992
AbstractTolmetin microspheres were prepared by the coacervation process from the ethylcellulose. Microspheres were obtained both in presence and without protecting colloids, such as polyisobutilene (PIB) or ethyl-vinylacetate copolimers (EVA). The effect of these agents on the preparation, drug content, wall thickness, surface morphology, drug dissolution arid release from microspheres, were evaluated. The dissolution rate analysis was carried out also in the presence of a surfactant (Tween 80) at different pH values.In addition, microspheres containing Tolmetin as a core material were submitted to biological tests, in comparison with the free drug, to evaluate upon experimental models the …
In silicoprediction of drug dissolution and absorption with variation in intestinal pH for BCS class II weak acid drugs: ibuprofen and ketoprofen
2012
The FDA Biopharmaceutical Classification System guidance allows waivers for in vivo bioavailability and bioequivalence studies for immediate-release solid oral dosage forms only for BCS class I. Extensions of the in vivo biowaiver for a number of drugs in BCS class III and BCS class II have been proposed, in particular, BCS class II weak acids. However, a discrepancy between the in vivo BE results and in vitro dissolution results for BCS class II acids was recently observed. The objectives of this study were to determine the oral absorption of BCS class II weak acids via simulation software and to determine if the in vitro dissolution test with various dissolution media could be sufficient …
Relationships betweenin vitrodrug dissolution andin vivoresponse
2012
In recent years there has been an effort to relate manufacturing variables to the performance of the dosage form from a clinical point of view (in terms of safety and efficacy). Consequently any control strategy or the establishment of meaningful specifications should take into consideration the clinical impact on the patient. Since plasma levels are considered to be one of the most useful surrogates for clinical safety (in that bioequivalent plasma levels are considered therapeutically equivalent) and dissolution is the best surrogate for bioavailability, it is a natural consequence that dissolution be used to establish the design space in which all the formulations would have similar safe…
COMPARATIVE-STUDY ON INCLUSION-COMPOUNDS OF 4-BIPHENYLACETIC ACID WITH BETA-CYCLODEXTRIN, HYDROXYPROPYLATED-BETA-CYCLODEXTRINS, AND METHYLATED-BETA-C…
1994
AbstractThe inclusion behavior of Hydroxypropyl-β-Cyclodextrin (HP-β-Cyd) and of methylated-β-Cyclodextrins, heptakis-(2,6-di-O-methyl)-β-Cyclodextrin (DM-β-Cyd) and heptakis-(2,3,6-tri-O-methyl)-β-Cyclodextrin (TM-β-Cyd), in solution and solid state was compared with that of natural β-Cyclodextrin (β-Cyd) using an anti-inflammatory drug, 4-biphenylacetic acid (BPAA), as a guest molecule. The solubility of BPAA with β-Cyd and β-Cyd derivatives in aqueous solution were determined. Stability constants were calculated by phase solubility method at various pH values and temperatures. The formation of inclusion complexes with β-Cyd and β-Cyd derivatives in the solid slate were confirmed by infra…
Interdiffusion in blends of polystyrene and polymethylstyrene studied by light scattering after temperature jumps across the phase boundary
1992
Abstract We describe a simple light scattering set-up for measuring interdiffusion coefficients D in polymer blends by generating spinodal decomposition and subsequent dissolution after temperature jumps across the phase boundary. In blends of polystyrene and polymethylstyrene (random copolymer of 60% m-methylstyrene and 40% p-methylstyrene) D values were obtained between 10−11 and 10−15 cm2s−1 at temperatures up to 50 K above the upper critical solution temperature. The results are discussed in relation to tracer diffusion in the same system.
In situ characterization of passive films on al-ti alloy by photocurrent and impedance spectroscopy
1998
Abstract The anodic behaviour of an Al-Ti alloy (Ti-48Al-1V, atomic %) was investigated in different aqueous electrolytes. In all cases the alloy was passive owing to the growth of a barrier-like oxide film according to the high field mechanism. The study of the growth curves suggests partial dissolution of the film during the formation process in acidic solution. The kinetic parameters for film formation have been estimated in neutral solutions and the dielectric constant of the passive layer was roughly estimated. The in-situ characterization of the passive film revealed a n-type behaviour only for very low thicknesses, whilst thicker films showed insulator-like characteristics. The analy…
Formulation predictive dissolution (fPD) testing to advance oral drug product development: an introduction to the US FDA funded ‘21st Century BA/BE’ …
2018
Over the past decade, formulation predictive dissolution (fPD) testing has gained increasing attention. Another mindset is pushed forward where scientists in our field are more confident to explore the in vivo behavior of an oral drug product by performing predictive in vitro dissolution studies. Similarly, there is an increasing interest in the application of modern computational fluid dynamics (CFD) frameworks and high-performance computing platforms to study the local processes underlying absorption within the gastrointestinal (GI) tract. In that way, CFD and computing platforms both can inform future PBPK-based in silico frameworks and determine the GI-motility-driven hydrodynamic impac…
Predicting Pharmacokinetics of Multisource Acyclovir Oral Products Through Physiologically Based Biopharmaceutics Modeling.
2021
Abstract Highly variable disposition after oral ingestion of acyclovir has been reported, although little is known regarding the underlying mechanisms. Different studies using the same reference product (Zovirax ®) showed that Cmax and AUC were respectively 44 and 35% lower in Saudi Arabians than Europeans, consistent with higher frequencies of reduced-activity polymorphs of the organic cation transporter (OCT1) in Europeans. In this study, the contribution of physiology (i.e., OCT1 activity) to the oral disposition of acyclovir immediate release (IR) tablets was hypothesized to be greater than dissolution. The potential role of OCT1 was studied in a validated physiologically-based biopharm…