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  • Chemical Engineering  (5)
  • 13C-NMR  (1)
  • 8′-hydroxy-dihydroergotamine  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 26 (1984), S. 463-470 
    ISSN: 1432-1041
    Keywords: dihydroergotamine ; 8′-hydroxy-dihydroergotamine ; plasma metabolites ; bioavailability ; receptor affinity ; healthy volunteers ; liver microsomal incubates
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The plasma concentrations and urinary excretion of dihydroergotamine and its metabolites have been measured after a single oral administration of 3 mg tritium-labelled drug to 6 male volunteers. The plasma level of non-volatile radioactivity declined biphasically with α- and β-phase half-lives of 2.1 h and 32.3 h, respectively. The peak plasma concentration was reached within 3.2h. Urinary excretion of total non-volatile radioactivity was low, amounting to 1.0% of the dose. The parent drug and four metabolites could be quantitated in urine and plasma samples. Metabolite 4 (8′-hydroxy-dihydroergotamine) was isolated from incubates of rat and monkey liver microsomal preparations. In human liver microsomal incubates, metabolite 4 was shown to be the primary metabolite of dihydroergotamine. In receptor binding studies performed with mammalian brain preparations, metabolite 4 had IC50-values at 6 monoaminergic binding sites similar to those of dihydroergotamine. Thus, it appears that the active principle consists at least of dihydroergotamine and its 8′-hydroxy derivative. As the concentration of metabolite 4 exceeded 5–7 times that of dihydroergotamine in urine and plasma, the bioavailability of dihydroergotamine should be reevaluated, taking into account the plasma concentrations of the parent drug and of its acitve metabolite, 8′-hydroxydihydroergotamine.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 36 (1990), S. 1807-1814 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Formaldehyde is one of the most important intermediate products of the chemical industry. Due to its high reactivity, it is commonly handled in aqueous or methanolic solutions. In these solutions, formaldehyde is dissolved chemically. Therefore, modeling thermodynamic properties of aqueous and methanolic formaldehyde-containing mixtures require the consideration of chemical reactions and physical effects. A recently published physico-chemical model (Maurer, 1986) for the description of vapor-liquid equilibria of these systems is tested and improved on the basis of about 140 new experimental data points for mixtures containing formaldehyde, water, methanol, and trioxane at temperatures between 320 and 380 K and pressures below 100 kPa. Improvements are achieved by fitting some of those binary interaction parameters, which formerly had to be estimated due to the lack of experimental data. The revised model is able to reliably predict vapor-liquid equilibria in multicomponent formaldehyde-containing mixtures.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 38 (1992), S. 1693-1702 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A physicochemical model for vapor-liquid equilibrium in multicomponent formaldehyde-containing mixtures (Maurer, 1986; Hasse et al., 1990; Hasse and Maurer, 1991a). is extended to describe enthalpy changes upon vaporization. Predicted enthalpy changes are compared with new experimental results. The measurements were carried out with a thin-film evaporator flow-calorimeter (Liu and Maurer, 1991). More than 80 experimental data points for mixtures of formaldehyde + water and formaldehyde + methanol + (small amounts of water) are reported. The data cover the temperature range from 323 to 363 K (formaldehyde + water) and 312 to 347 K (formaldehyde + methanol) at liquid phase formaldehyde mole fractions up to about 0.3 (formaldehyde + water) and 0.6 (formaldehyde + methanol). Comparisons between predicted and experimental results for the enthalpy change reveal deviations of only a few percent. Further improvements are achieved by fitting some model parameters, which originally were estimated from noncalorimetric data.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 39 (1993), S. 1527-1538 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Most models for describing activity coefficients in ionic solutions are only appropriate for single aqueous electrolyte solutions. Extensions to mixed electrolyte solutions are rarely found and are often unreliable, especially at higher electrolyte concentrations. A new model is developed by combining ionic solvation equilibria and physical interaction forces. It is shown that by using the parameters correlated from single electrolyte aqueous systems, the activity coefficients in mixed electrolyte aqueous solutions can be accurately predicted up to the solubility limit, for example, at very high ionic strength.
    Additional Material: 6 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 42 (1996), S. 1741-1752 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A physicochemical model for vapor-liquid equilibria and enthalpies in formaldehyde-containing mixtures is revised and extended using recently published NMR spectroscopic data on chemical equilibria in aqueous and methanolic formaldehyde solutions as well as new vapor-liquid equilibrium data for the system formaldehyde-water at temperatures up to 413 K (pressures up to 450 kPa), which were taken in this work with a new apparatus. Furthermore, the model is revised so that it can be extended straight-forwardly to explicitly account for reaction kinetic effects based on results from other recent NMR spectroscopic studies. The model is tested over the entire temperature range (293-413 K), where reliable experimental data on vapor-liquid equilibria are available, and against calorimetric data. Typical relative deviations between experimental data and the correlation are about 5% for vapor-liquid partition coefficients and 2% for the pressure. Deviations between calculated and measured enthalpies of vaporization are generally below 2%.
    Additional Material: 12 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 10 (1987), S. 71-76 
    ISSN: 0935-6304
    Keywords: Preparative HPLC ; Anion exchange chromatography ; Metabolites ; Structure of glucuronide ; 1H-NMR ; 13C-NMR ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 890 ml of urine of rats treated with [14C] 205-734 was desalted over an Amberlite XAD-2 adsorption column. The methanol extract dissolved in 10 ml methanol was injected onto an anion exchange column (Nucleosil 10 SB 250 × 16 mm i.d.) equilibrated in methanol. A gradient of decreasing methanol proportion versus a 0.2 M ammonium hydrogen carbonate buffer eluted a pure glucuronide of 205-734. Its structure was established by NMR, MS, UV, and IR analyses. This procedure is simple, rapid, and very selective for the compound of interest.
    Additional Material: 3 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 32 (1986), S. 932-948 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The vapor-liquid equilibria in the binary mixtures water-formaldehyde and methanol-formaldehyde are precisely correlated by introducing a physicochemical model that takes into account physical forces of interactions as well as chemical reactions. The most valuable feature of the model is its simple extension to multicomponent mixtures. From binary data alone the model is capable of accurately predicting vapor-liqid equilibria in complex mixtures such as formaldehyde-water-trioxane and formaldehyde-water-methanol. This is demonstrated by comparing calculated data with experimental results taken from the literature or measured in this work, at temperatures between about 310 and 400 K at pressures up to 500 kPa, and formaldehyde concentrations in the liquid phase of up to about 70 mol %.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
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