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  • 35.80 + s  (1)
  • Chronopharmacology  (1)
  • S-1452  (1)
  • 1990-1994  (3)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 43 (1992), S. 501-505 
    ISSN: 1432-1041
    Keywords: S-1452 ; thromboxane A2 receptor antagonist ; nocturnal dosage ; platelet aggregation ; circadian rhythm ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary It is well known that platelet aggregation shows a morning rise, which may contribute to the increase in the onset of ischaemic heart diseases during the morning period. The present study was undertaken to determine whether nocturnal dosage with S-1452, a thromboxane AZ receptor antagonist, would blunt the morning rise in platelet aggregability. S-1452 50 mg or placebo were given orally to 8 healthy subjects at 10.00 h (day trial) or 22.00 h (night trial) according to a cross-over design. Plasma concentrations of S-1452 and its metabolites, bisnor-( + )-S-145 and tetranor-(+ )-S-145, and platelet aggregation were determined during the 12-hour period following the dose. Mean plasma concentrations of S-1452, bisnor-( + )-S-145 and tetranor-(+ )-S-145 during the absorption phase were lower after the nocturnal dose than after the morning dose. The maximum plasma concentration and area under the plasma concentration-time curve of the compounds were also lower and the time to the maximum concentration were delayed after the treatment at night. A morning rise in platelet aggregation was observed following placebo treatment. The inhibitory effect of S-1452 on platelet aggregation was observed at 3 hours and persisted for up to 9 h in both trials. The results suggest that S-1452 is absorbed more slowly after the nocturnal dose than after the morning dose. However nocturnal treatment with 50 mg S-1452 may blunt the morning rise in platelet aggregability.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 44 (1993), S. 489-492 
    ISSN: 1432-1041
    Keywords: Chronopharmacology ; Propranolol ; absorption ; age
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary There is diurnal variation in the absorption rate of propranolol in younger subjects. This study was undertaken to examine the effect of age on the chronopharmacokinetics of propranolol. We gave 20 mg of propranolol orally to 13 younger and 11 older hypertensive subjects at 09.00 h (day study) or 21.00 h (night study) in a cross-over design. Plasma concentrations of propranolol and its metabolites, 4-hydroxypropranolol and naphthoxylactic acid, were determined just before and at 0.5, 1, 1.5, 2, 3, 4, 6, 12, and 24 h after dosage. In the younger subjects the absorption rate constant (ka) of propranolol and its maximum plasma concentration (Cmax) were significantly higher and the time to maximum concentration (tmax) was significantly shorter in the day than at night. There were similar time-variant changes in Cmax and tmax for 4-hydroxypropranolol and naphthoxylactic acid. In contrast, there were no time-variant changes in ka, Cmax and tmax of propranolol and its metabolites in the older subjects. These results suggest that propranolol is absorbed more rapidly after morning dosing than after night-time dosing in younger but not in older subjects. Based on these findings, we speculate that the time-variance in the absorption rate or first-pass elimination, or both, of propranolol diminish with age.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 20 (1991), S. 197-200 
    ISSN: 1434-6079
    Keywords: 36.40. + d ; 35.80 + s
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Metastable uni-cluster dissociation for several hydrogen-bonded and van der Waals cluster ions are observed via resonance-enhanced two-photon ionization reflectron time-of-flight (TOF) mass spectrometry. All of the cluster ions studied show evaporation of a single molecule from the respective parent cluster ions as dominant metastable decay processes. Furthermore, the averaged metastable evaporation rate constants (k evap) of these cluster ions in a fixed time domain of 0.2–50 µs are obtained by analyzing the relative intensity of metastable ion peaks due to evaporation in the acceleration and the field-free drift regions of the TOF mass spectrometer. An intensity anomaly in some of the observed metastable ion peaks, indicative of magic number stability of the cluster ion, is also presented.
    Type of Medium: Electronic Resource
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