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  • 1
    Electronic Resource
    Electronic Resource
    Determination of Extent of Formaldehyde-Induced Crosslinking in Hard Gelatin Capsules by Near-Infrared Spectrophotometry (1997)
    Springer
    Pharmaceutical research 14 (1997), S. 1046-1050 
    Details
    ISSN: 1573-904X
    Keywords: gelatin ; crosslinking ; formaldehyde ; dissolution ; near-infrared spectrophotometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. To predict the degree of crosslinking from formaldehyde-stressed hard gelatin capsules (HGCs) using near-infrared spectrophotometry (NIR). Methods. HGCs were exposed to a 150 ppb atmosphere of formaldehyde for 2.25,4.60,9.42, 16.0 and 24.0 hours. The capsules were filled with fresh amoxicillin, placed in a 90° conical reflector cone, and scanned in a NIR spectrophotometer. Principal component regression (PCR) was employed to analyze the spectra of the intact capsules. Dissolution profiles were then obtained for each experimental group. Results. The dissolution of amoxicillin from the capsules at pH 1.2 was found to decrease with increasing time of exposure to the formaldehyde atmosphere. A set of principal components (PCs) was formed by a linear combination of the absorbance values at each wavelength scanned. A good correlation was established (r2 = 0.963) when PC values from the NIR spectra of the HGCs were regressed against percentage of amoxicillin dissolved at 45 minutes, at pH 1.2. Water content of the capsules was found to be the largest determinant in the variation between HGC spectra at each exposure time. Conclusions. NIR spectrophotometry, combined with PCR, was successful at not only predicting dissolution of HGCs exposed to formaldehyde, but also at determining which wavelengths contributed most to spectral variation of these stressed HGCs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1012105412735
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  • 2
    Electronic Resource
    Electronic Resource
    Influence of Tablet Dissolution on Furosemide Bioavailability: A Bioequivalence Study (1987)
    Springer
    Pharmaceutical research 4 (1987), S. 150-153 
    Details
    ISSN: 1573-904X
    Keywords: furosemide ; bioavailability/bioequivalence ; dissolution ; intersubject variability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract In order to evaluate the in vitro dissolution and in vivo bioavailability relationship for furosemide, a bioequivalence study was carried out. Furosemide (40 mg) was administered orally to 12 normal volunteers in a 6 × 6 crossover design using six products (five tablets and one solution) obtained from three pharmaceutical companies. Plasma and urine concentrations of furosemide were quantitated by high-performance liquid chromatography (HPLC). Plasma furosemide profiles were analyzed by non-compartmental methods. Compared to the oral solution, all of the formulations exhibited lower peak furosemide concentrations, longer mean residence times, and, in some cases, diminished bioavailability (range, 66–96%). Similar results were obtained when the reference product (a rapidly dissolving tablet) was used as the standard. All of the products failed the 75/75 rule when compared to either reference standard, apparently because of large intersubject variability. The total amount of furosemide excreted in urine could be associated with the percentage drug dissolved (in vitro) at 30 min. The pH 5.6 dissolution medium (compared to pH 4.6) appears to be an appropriate test medium for assuring batch uniformity and bioequivalence of furosemide products.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1016427321532
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  • 3
    Electronic Resource
    Electronic Resource
    Polystyrene resins with immobilized polyamines: Preparation, characterization, and ability to bind Cu(II) ions (1977)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 15 (1977), S. 525-531 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Three polyamine ligands, ethylenediamine (EDA), diethylenetriamine (DTA), and triethylenetetramine (TETA), were bound to three chloromethylated “popcorn” polystyrene resins (16, 50, and 100% phenyl ring substitution) with the use of pyridine as the reaction medium. The rate of chloride displacement decreased with increasing molecular weight of the amine and higher degree of resin chloromethylation, while the extent of multiple attachments to the polymer matrix increased. The additional crosslinking, a result of multiple attachments, caused the polyamine resins to swell to a lesser extent in pyridine and water. The ability of the insoluble polyamine-polystyrene resins to chelate Cu2+ ions from dilute solutions (200 ppm) was determined at pH 5. With EDA resins the capacity for Cu2+ increased with increasing amount of the bound polyamine, with DTA it remained unchanged, while with TETA it was found to decrease.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1977.170150301
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