Search results for "Particle Size"
showing 10 items of 631 documents
Performance of a Chromolith RP-18e column for the screening of β-blockers
2009
The chromatographic performance of a monolithic column (Chromolith RP-18e) was comprehensively examined in the isocratic separation of ten beta-blockers, using ACN-water mobile phases, and compared with the performance of three microparticulate RP columns manufactured with different types of silica: Spherisorb ODS-2, Kromasil C18 and XTerra MS C18. The comparison considered the analysis time, selectivity, peak shape (column efficiency and asymmetry) and resolution, and was extended to a wide range of mobile phase compositions. The Chromolith column showed good performance for the analysis of beta-blockers with regard to the packed columns. In terms of selectivity and analysis time, the grea…
An experimental method for the determination of the photon flow reflected and absorbed by aqueous dispersions containing polycrystalline solids in he…
1991
An experimental method for the evaluation of the photon flow reflected and absorbed by aqueous dispersions containing polycrystalline solids is proposed. The method is based on actinometric measurements. It is shown that the values obtained are independent of the particle sizes and of the concentration of the solids at least in the experimental conditions and in the range used in the present study (particle size range: 40–500 μm; solids concentration: 0.1–2 g liter−1). The results suggest that the values obtained should be attributed to the interfaces formed between the surface of the solids and the medium. The method is applied to a photocatalytic reaction, namely to the photodegradation o…
Pefloxacine mesilate- and ofloxacin-loaded polyethylcyanoacrylate nanoparticles: characterization of the colloidal drug carrier formulation.
1995
The entrapment of fluoroquinolones, perfloxacine mesilate (PFX) and ofloxacin (OFX), in polyalkylcyanoacrylate (PECA) nanoparticles could offer some advantages for their biological application; for examples, increasing their bioavailability, controlling the drug time-release in blood, and reducing the formation of bacterial resistance. To load these two drugs in PECA polymeric bulk, the incorporation or adsorption method was performed. These two methods were capable of influencing nanoparticle size, molecular weight, release profile, and drug–polymer association. The incorporation method, particularly for the OFX system, achieved PECA nanoparticle suspensions with a mean size value three ti…
Dry adsorbed emulsion: 1. Characterization of an intricate physicochemical structure
2000
Abstract A recent solid pharmaceutical form called “Dry Adsorbed Emulsion” (DAE) was characterized in morphological and structural fields. A DAE is an intricate system initiated by a water‐in‐oil emulsion including the active drug (i.e., theophylline). Each emulsion phase is adsorbed on pulverulent adsorbents with a suitable polarity (silica) to obtain a free‐flowing powder with nonporous particles of size from 125 to 710 μm, with small specific surface area and a spherical shape. Different methods, such as scanning electron microscopy combined with chemical microanalysis, dying tests, and electron spin resonance studies, allow the formulator to follow the behavior of DAE aqueous and oily p…
A novel technique for intraduodenal administration of drug suspensions/solutions with concurrent pH monitoring applied to ibuprofen formulations
2019
Characterization of dissolution of solid suspended drug particles in vivo is important for developing biopredictive in vitro tests. Therefore, methods to gain deeper insights into particle dissolution in vivo are needed. The soft Bioperm intubation method, a well established tool for investigation of permeability, absorption, metabolism, and drug interactions at predefined locations in the gastroinstinal tract, was modified. The novel intubation method involved pump-controlled infusion of pharmaceutical suspensions as well as simultaneous pH monitoring. This technique was used in a proof of concept study in healthy humans. Plasma sampling and non-compartmental analysis allowed comparison of…
Comparability of two different polyacrylamide gel electrophoresis methods for the classification of LDL pattern type
2011
Abstract Background The measurement of small dense low-density lipoprotein (sdLDL) particles is relevant when assessing cardiovascular risk. However, there is as yet no referenced method for the determination of LDL subfractions or a standardized comparison of the methods currently available. Therefore, the aim of this study was to compare the pattern of LDL particles measured by polyacrylamide tube gel electrophoresis (PTGE) and polyacrylamide gradient gel electrophoresis (PGGE) and to correlate the results with triglyceride concentration. Materials and methods Serum samples were collected from 177 patients. Lipid profile and LDL particle size were assessed using PTGE and PGGE. Results Pea…
Changes in plasma lipids and low-density lipoprotein peak particle size during and after acute myocardial infarction
2002
In summary, LDL peak particle size variations occur very early after AMI, and therefore this parameter, which may be considered a genetically determined risk factor, must be measured not before 2 to 3 months after the acute event.
LDL particle size and composition and incident cardiovascular disease in a South-European population: The Hortega-Liposcale Follow-up Study.
2018
Abstract Background The association of low-density lipoprotein (LDL) particle composition with cardiovascular risk has not been explored before. The aim was to evaluate the relationship between baseline LDL particle size and composition (proportions of large, medium and small LDL particles over their sum expressed as small-LDL %, medium-LDL % and large-LDL %) and incident cardiovascular disease in a population-based study. Methods Direct measurement of LDL particles was performed using a two-dimensional NMR-technique (Liposcale®). LDL cholesterol was assessed using both standard photometrical methods and the Liposcale® technique in a representative sample of 1162 adult men and women from Sp…
Mass Output and Particle Size Distribution of Glucocorticosteroids Emitted from Different Inhalation Devices Depending on Various Inspiratory Paramet…
2002
Efficient inhalation therapy depends on successful delivery of the drug to the lung. The efficacy of drug delivery is not only influenced by the characteristics of the inhalation device, but also by the patient's handling of the device and by the inspiratory maneuver achieved through the device. We analyzed the output characteristics of three different chlorofluorocarbon (CFC)-free breath-actuated inhalers for inhaled glucocorticosteroids (BUD Turbohaler, FP Diskus/Accuhaler and HFA-BDP Autohaler, respectively). Mass output and particle size distribution of drug aerosol delivered by the inhalers were determined depending on different inhalation parameters in vitro using an Andersen cascade …
Atherogenic lipoprotein phenotype and low-density lipoproteins size and subclasses in women with polycystic ovary syndrome.
2006
Abstract Context: An altered lipid profile is common in polycystic ovary syndrome (PCOS) and is usually characterized by increased triglycerides and low high-density lipoprotein (HDL)-cholesterol levels. In the general population, these alterations are often associated with the increase of small low-density lipoproteins (LDLs) in the so-called “atherogenic lipoprotein phenotype” (ALP) that determines a further increase of cardiovascular risk. In this study, we evaluated the presence of ALP in the plasma of women with PCOS. Setting: Measurements and analysis of LDL size were performed at the Clinic of Endocrinology, Diabetes, and Clinical Nutrition, University Hospital, Zurich. PCOS patients…