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  • 1
    Electronic Resource
    Electronic Resource
    Bioavailability and pharmacokinetics of theophylline in plain uncoated and sustained-release dosage forms in relation to smoking habit I. Single dose study (1983)
    Springer
    European journal of clinical pharmacology 24 (1983), S. 79-87 
    Details
    ISSN: 1432-1041
    Keywords: theophylline ; smoking habit ; absolute bioavailability ; pharmacokinetics ; sustained release preparation ; plain tablet preparation ; antipyrine pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The bioavailability and pharmacokinetics of theophylline from a plain uncoated and 2 newly designed, sustained-release tablet formulations, as compared to intravenous aminophylline, were studied in 12 healthy adult male volunteers. The subjects were divided into two groups (n=6) with respect to smoking habit and on 4 separate occasions each received, on a randomized cross-over basis, a single dose of 400 mg equivalent of theophylline from every dosage form. The intravenous aminophylline study showed that habitual smoking had a significant (p〈0.05) effect on plasma theophylline clearance (0.051±0.006 vs 0.035±0.004 l/kg/h). Smoking significantly reduced the raw AUC from the 4 dosage forms (p〈0.05), but did not change the characteristics of absorption of each formulation. There was a non-significant trend towards reduced absolute bioavailability of theophylline from sustained-release formulations in smokers (percentage mean difference — 16% for one formulation and 13% for another). The trend was not observed for the plain uncoated tablet, which was rapidly absorbed (p〈0.01 to 0.05 in Ka, tmax and Cmax compared to sustained-release tablets). Similarity of the in vitro dissolution profiles of the two sustained-release formulations did not imply similarity of the in vivo absorption characteristics. Plasma clearances of theophylline and antipyrine were significantly correlated (p〈0.05,r=0.693,n=10). Thus, smoking enhanced the elimination of theophylline regardless of the dosage form administered. However, the extent to which habitual smoking may affect the hepatic first-pass effect on theophylline from sustained-release formulations requires further study. The results also suggest that theophylline and antipyrine may share a similar or common and presumably polycyclic hydrocarbon-inducible form(s) of microsomal drugmetabolizing enzyme.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00613931
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  • 2
    Electronic Resource
    Electronic Resource
    Bioavailability and pharmacokinetics of theophylline following plain uncoated and sustained-release dosage forms in relation to smoking habit (1983)
    Springer
    European journal of clinical pharmacology 24 (1983), S. 361-369 
    Details
    ISSN: 1432-1041
    Keywords: theophylline ; smoking ; sustained release formulation ; dosage forms ; multidose pharmacokinetics ; bioavailability ; circadian variation in kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The pharmacokinetics and bioavailability of theophylline following 10 days of multiple doses of a plain uncoated (640 mg, q.i.d.) and a sustained-release tablet formulation (600 mg, b.i.d.) were related to habitual smoking in 11 healthy adult male volunteers, who had previously taken part in a single-dose study of an intravenous preparation of theophylline and of the same oral dosage form. There were significant differences (p〈0.05 to 0.01) in the steady-state mean and minimum theophylline concentration and AUC between the groups (6 smokers versus 5 nonsmokers), but not between other variables. A difference (p〈0.05) in peak time was also found between the dosage forms. The mean elimination t1/2 was significantly (p〈0.05) shorter in smokers than in nonsmokers. The intersubject variability in plasma theophylline concentration observed on the final trial day in the smoking group was larger and diverged more from simulation curves generated from the mean pharmacokinetic parameters of the single-dose study of the same formulations as compared to that of the nonsmoking group. There was no significant difference between the two groups in the mean accumulation ratio and absolute bioavailability of the two dosage forms. The mean morning (7 a.m.) trough theophylline concentrations after both formulations were significantly (p〈0.05 to 0.01) greater than the evening (7 p.m.) values within the same group. The average number of reported side-effects was significantly (p〈0.001) greater during the earlier period (Days 1 to 3) than the later period of the trial. A trend was observed suggesting that the incidence of side-effects was less in smokers than in nonsmokers. The results indicate that smoking is a determinant not only of enhanced elimination of theophylline but that it also produces more variability in the plasma level, irrespective of the dosage form administered or the dosing scheme employed. There may be circadian variation in theophylline kinetics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00610056
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  • 3
    Electronic Resource
    Electronic Resource
    Effect of theophylline on respiratory neuromuscular drive (1987)
    Springer
    European journal of clinical pharmacology 33 (1987), S. 85-88 
    Details
    ISSN: 1432-1041
    Keywords: theophylline ; aminophylline ; incremental concentration ; occlusion pressure ; maximum inspiratory pressure ; transdiaphragmatic pressure ; ventilatory function
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary To investigate the possible mechanisms by which theophylline affects the control of ventilation, neuromuscular drive and ventilatory function were examined in 7 healthy men receiving an incremental intravenous aminophylline dosing schedule to achieve plasma theophylline concentrations of 5, 10, and 15 µg/ml. As compared with the baseline (predose) values, the 3 incremental aminophylline doses significantly (p〈0.05 to 0.01) increased occlusion pressure (P0.1) and maximum inspiratory pressure static (MIPS) at functional residual capacity (FRC). This was not observed for ventilatory flow $$(\dot V)$$ , tidal volume (VT), inspiratory time to total breathing cycle time ratio (Ti/Ttot), VT/Ti, and effective impedance [P0.1/(VT/Ti)]. When maximum electrical activity of diaphragm (Edimax) and transdiaphragmatic pressure (Pdimax) were examined in 3 of the 7 subjects, Pdi/Edi tended to increase with increasing theophylline concentrations, while Edimax did not. Our results suggest that the increase in P0.1 during the increase in aminophylline dose is caused by an improvement in respiratory muscle contractility, rather than by a central effect or by an increase in neural drive.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00610386
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  • 4
    Electronic Resource
    Electronic Resource
    Studies of the grassland vegetation in the kawatabi special research area of the Japanese IBP (1973)
    Springer
    Plant ecology 28 (1973), S. 41-56 
    Details
    ISSN: 1573-5052
    Keywords: Computertabulation ; Phytosociology ; Miscanthus sinensis ; Grassland ; Japan-IBP
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Zusammenfassung 1. Die Arbeit berichtet über die Analyse einer pflanzensoziologischen Tabelle mit Hilfe eines Komputerprogrammes. Als Rohtabelle wurden die Aufnahmen von der japanischen IBP Graslandstation in Kawatabi verwendet. Die übliche Handsortierung der Tabelle wird mit der Komputersortierung verglichen. Dieser Vergleich war Teil eines Testes für die Brauchbarkeit einer vonLieth & Moore entwickelten Komputersimulation der klassischen pflanzensoziologischen Tabellierungsmethode. Die Tabellen 2–6 und Abb. 2 demonstrieren Grenzen und Brauchbarkeit der beschriebenen Komputersortierung. Die Möglichkeit der Eingliederung pflanzensoziologischer Tabellen als Matritzen in ökologische Komputermodelle anderer Art wird erörtert. 2. Die Vegetation der J-IBP Grasland-Station wird beschrieben und deren Beziehungen zu einigen Umweltsfaktoren diskutiert (Tabellen 2 und 5, Abb. 1). Die Vegetationsdecke besteht im Wesentlichen aus verschiedenenMiscanthus sinensis-Grasland Typen. Einige Bewirtschaftungseinflüsse auf die Vegetationsdecke werden behandelt. Die oberirdische Primärproduktivität des Graslandes variiert in den Grenzen von 300 g bis 1500 g (von 400 g bis 600 g unter gewöhnlichen umständen) Trockensubstanz je m2 und Jahr.
    Notes: Summary 1. The paper demonstrates the utilization of a computerized vegetation analysis on the field data gathered at the Japanese IBP Grassland Site. Hand- and computer sorting procedures are compared and discussed. This part of the paper was a test of the usefulness of the computer simulation of the standard sorting procedures of phytosociological work. Tables 2–6 and Figure 2 demonstrate the usefulness as well as the limitations of the computer analysis. The possibility of incorporating phytosociological tables as matrices into computerized ecosystems models is suggested. 2. The vegetation of the J-IBP Grassland Site is described and preliminary evaluations made with regard to environmental parameters (Table 2 and 5, Figure 1). Some management influences on theMiscanthus grassland are discussed. The primary above-ground productivity ranges from 300 to 1500 g (usually 400 to 600 g) dry matter per m2.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02386213
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