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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 24 (1983), S. 761-767 
    ISSN: 1432-1041
    Keywords: theophylline ; bioavailability ; sustained release tablet ; pharmacokinetics ; Theograd-250
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The bioavailability of theophylline after oral administration of a new sustained release tablet Theograd®-250 mg was studied in 7 healthy volunteers, under fasting and non-fasting conditions. Whilst fasting the bioavailability was moderate at 64±22% (mean±SD), whereas in the non-fasting state the relatively high bioavailability of 90±13% was found. The drug appeared to be significantly more slowly absorbed when a tablet was taken after a meal, than when it was ingested on an empty stomach. In the former case, the peak level was reached after 6.9±1.0 h, whereas in the fasting state the maximum serum concentration occurred 4.0±1.7 h after administration of the drug. Despite the slow absorption, the peak non-fasting level of 4.4±1.4 mg·l−1 was significantly higher than the 3.1±1.0 mg·l−1 observed in the fasting state. The profiles of the serum concentration-time curves showed that the concentration remained above 75% of Cmax for 8.7±1.3 h in the fasting and 9.0±1.1 h in the non-fasting state. It was concluded that to define the optimal dosage regime for sustained release oral dosage forms of theophylline, the influence of food on absorption from these preparations should be taken into account. Based on the present results, Theograd®-250 mg tablets have predictable absorption and a high (90%) bioavailability if taken after a meal.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Pharmacy world & science 1 (1979), S. 449-456 
    ISSN: 1573-739X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Two polymorphic forms of acetohexamide have been characterised using differential scanning calorimetry, scanning electron microscopy and X-ray diffraction. For both polymorphic forms the dissolution rates and solubilities have been investigated. The phosphate buffer (pH 7.6) prescribed in the usp xix as the medium for the dissolution test of acetohexamide tablets cannot be used, because a less soluble potassium salt crystallises during the dissolution process.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Pharmacy world & science 2 (1980), S. 365-366 
    ISSN: 1573-739X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Pharmacy world & science 2 (1980), S. 366-366 
    ISSN: 1573-739X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Pharmacy world & science 3 (1981), S. 243-244 
    ISSN: 1573-739X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Pharmacy world & science 10 (1988), S. 254-258 
    ISSN: 1573-739X
    Keywords: Administration, sublingual ; Biological availability ; Disintegration ; Dissolution ; Drug compounding ; Glyceryl trinitrate ; Tablets
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Thein vitro andin vivo availability of nitroglycerin from three compressed and one stabilized molded tablet have been studied. Compressed nitroglycerin tablets have to disintegrate before the drug is released. The disintegration and release of nitroglycerin from these tablets appeared to be strongly dependent upon conditions in thein vitro dissolution tests, such as the degree of agitation, andin vivo factors, such as tongue pressure and/or movement. The stabilized molded nitroglycerin tablet did not disintegrate but dissolved completely. Because the dissolution of the molded tablet was fast, the release rate of nitroglycerin was far less influenced by thein vitro andin vivo factors described above. The potency andin vitro andin vivo availability of fresh tablets and tablets which had been stored in tightly closed glass containers for over one year did not differ significantly. It is conjectured that the supposed potency loss of properly stored compressed nitroglycerin tablets is rather a release problem than a stability problem.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1573-739X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The bioavailability of theophylline and the serum concentration fluctuations after administration of a sustained release tablet (Theograd® 250 mg, one tablet twice daily) were studied in the steady state in six volunteers. On postprandial administration of the 250 mg tablets the bioavailability was 89±16%. Good sustained release properties were obtained provided that the tablets were taken after a meal; Cmax was 7.9±2.0 mg.l−1,t max was 5.3±1.6 h, the peak-trough difference was 2.3±0.6 mg.l−1 and the serum concentration fluctuation was accounted for 42.8±11.2%. It was shown that on postprandial administration the mean serum concentration-time profile could be successfully calculated by means of multiple dose projection from single dose data. However, when the a.m. dose was given on an empty stomach and the p.m. dose 3 h after a meal, it appeared not to be possible to use the single diurnal dose data for calculation of the steady state serum concentration-time profile: the experimentally observed a.m. trough levels were significantly higher than the p.m. trough values and also the observed mean serum concentration was significantly higher than the calculated level. The possible causes for this discrepancy are extensively discussed.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Pharmacy world & science 2 (1980), S. 541-547 
    ISSN: 1573-739X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract This paper reports a comparative evaluation of thein vivo andin vitro availability of pure and hydrophilised hexobarbital from capsules. Hydrophilization of the poorly soluble hydrophobic drug was performed by coating the powder particles with hydrophilic methylcellulose. Liquid penetration into plugs of the treated powder, disintegration times andin vitro release rates became independent of the liquid wetting potency and were extremely fast compared with the pure drug. A bioavailability study in eight healthy volunteers showed a strongly increased extent and rate of absorption of the treated drug compared with the pure drug. The absorption rate of the hydrophilised free acid of hexobarbital was almost as rapid as that of the sodium salt.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Pharmacy world & science 10 (1988), S. 246-253 
    ISSN: 1573-739X
    Keywords: Content uniformity ; Drug compounding ; Drug packaging ; Drug stability ; Drug storage ; Glyceryl-trinitrate ; Tablets
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The physical stability of one type of stabilized molded and three types of compressed nitroglycerin tablets was studied. The evaporation rate of nitroglycerin was controlled by its vapour pressure and by the matrix effect of the dosage forms. The four products showed different vapour pressures and matrix effects. In time nitroglycerin escapes from the outmost layers of the tablets; the dosage form in which the drug showed the lowest vapour pressure (the stabilized molded tablet) was found to be the most stable one. However, from the time when the drug had escaped from the outmost layers of the dosage form, the matrix effect became dominant. When nitroglycerin tablets were stored in tightly closed containers at room temperature potency loss was minimal. Even when the bottles were opened regularly this did not result in a significant loss of the drug. Measures are suggested to minimize drug evaporation.
    Type of Medium: Electronic Resource
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