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  • 1
    Electronic Resource
    Electronic Resource
    Evaluation of multipoint kinetic methods for immunoassays: kinetic quantitation and immunoglobulin G (1986)
    s.l. : American Chemical Society
    Analytical chemistry 58 (1986), S. 2306-2312 
    Details
    ISSN: 1520-6882
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ac00124a042
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Gradient High Performance Liquid Chromatographic Assay for Degradation Products of Adinazolam Mesylate in a Sustained Release Tablet Formulation (1995)
    Springer
    Pharmaceutical research 12 (1995), S. 738-745 
    Details
    ISSN: 1573-904X
    Keywords: adinazolam mesylate ; gradient reversed-phase liquid chromatography ; mass spectrometry ; decomposition products assay
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A gradient high performance liquid chromatographic method was developed to determine degradation products of adinazolam mesylate in a sustained release tablet formulation. Sample preparations were chromatographed on a YMC-Basic column using a formate buffer/acetonitrile gradient with absorbance detection at 254 nm. Adinazolam mesylate was found to degrade at high relative humidity and temperature to form a major product, the 6-aminoquinoline analog, plus numerous other compounds. Five of these compounds were identified and their structures indicate that the solid-state degradation of adinazolam, in the presence of sufficient moisture, involves not only a hydrolytic mechanism, but also an oxidative mechanism. Potential process impurities were resolved from the drug and degradation products. Recovery was near 100% over the 0.5 to 10% range for the major degradate (6-aminoquinoline) and over the 0.5 to 1% range for the other analytes. The method was applied to tablet samples stressed at high relative humidity and temperature. The relative standard deviation of the assay for the 6-aminoquinoline was less than 2% and less than 13% for the minor components. Calculated mass balances (sum of adinazolam plus degradation products in the degraded tablet divided by the same sum in the undegraded tablet) were less than 100% and were dependent on the extent of degradation in the tablet. The average mass balance result obtained for samples that were an average of 9.5% degraded was 95.0 ± 1.5%. It is possible that the decrease in mass balance with increase in percent degradation may be explained by the formation of many components at trace levels due to degradation by various permutations of hydrolytic and oxidative reaction pathways.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1016219927912
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Diffusion in HPMC Gels. II. Prediction of Drug Release Rates from Hydrophilic Matrix Extended-Release Dosage Forms (1995)
    Springer
    Pharmaceutical research 12 (1995), S. 965-971 
    Details
    ISSN: 1573-904X
    Keywords: dissolution ; diffusion coefficient ; HPMC ; extended-release formulation ; mathematical model ; prediction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. A mathematical model is described for the prediction of the relative change in drug release rate as a function of formulation composition for HPMC-based extended-release (ER) tablets of adinazolam mesylate and alprazolam. Methods. The model is based on the equation derived by Higuchi for the diffusional release of soluble drugs from polymeric matrices and on our recent measurements of the concentration dependency of adinazolam diffusivity in dilute HPMC gels and solutions. The assumptions made in applying the model include (i) that diffusion is the sole mechanism of drug release (i.e. swelling kinetics are ignored), and (ii) that the surface area-to-volume ratio and concentrations of adinazolam, lactose and HPMC in the gel layer are proportional to that of the dry tablet. Results. Reasonable correlations were obtained between the experimental drug release rate ratios and the predicted drug release rate ratios for ER adinazolam mesylate (R2 = 0.82) and low-dose (0.5 mg) ER alprazolam tablets (R2 = 0.87). The predictive power for a 6-fold higher dose of ER alprazolam tablets was not as good (R2 = 0.52). Conclusions. These results are consistent with previous knowledge of the release mechanisms of these formulations. ER adinazolam mesylate and ER alprazolam 0.5 mg exhibit primarily a diffusion controlled release mechanism, while ER alprazolam 3 mg deviates from pure diffusional release. The limitations of the model are discussed and point to the need for continued study of the swelling kinetics of matrix ER systems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1016246028338
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    In Vitro and in Vivo Evaluation of Whole and Half Tablets of Sustained-Release Adinazolam Mesylate (1991)
    Springer
    Pharmaceutical research 8 (1991), S. 1482-1488 
    Details
    ISSN: 1573-904X
    Keywords: adinazolam mesylate ; oral sustained release ; matrix sustained release ; mechanism ; in vivo/in vitro correlation ; bioavailability ; absorption
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The mechanism of release from sustained-release adinazolam mesylate tablets was assessed by the Higuchi equation and by analysis of drug release profiles through 60% released using the Peppas equation. Computed values of the diffusional exponent, n, ranged from 0.59 to 0.66. Values of n in this range are consistent with a mixed mechanism of release, with diffusion of drug through the hydrated polymer matrix and relaxation of this matrix being the principal processes controlling release. The rate of in vitro drug release was increased for half tablets relative to whole tablets and is attributed to an increase in the surface to volume ratio of half tablets of about 16%. This increase in surface-to-volume ratio of half tablets was reflected by an increase in the constant, k, from the Peppas equation of 20–23% and by an increase in the slope of Higuchi plots of 12–18% for four lots of tablets. In vivo/in vitro relationships from two bioavailability studies were thoroughly evaluated. Using either a linear or a quadratic relationship, an in vivo/in vitro correlation exists for sustained-release adinazolam mesylate tablets.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1015834114359
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    Paper (German National Licenses)
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