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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 38 (1990), S. S108 
    ISSN: 1432-1041
    Keywords: carvedilol ; enantiomer pharmacokinetics ; bioavailability ; first-pass effect
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The racemic compound carvedilol is a multiple-action oral antihypertensive drug that exhibits both vasodilator and non-selective beta-adrenergic blocking activities. The effects of the levorotatoryS-enantiomer [S( − )-CARV] are vasodilatation and beta-blockade. TheR (+)-enantiomer [R (+)-CARV] is a pure vasodilating agent. Quantitative determination of the enantiomers in human plasma by HPLC was carried out after formation of diastereoisomers with the chiral reagent 2,3,4,6-tetraO-acetyl-β-d-glucopyranosyl isothiocyanate (GITC). The pharmacokinetics of the enantiomers were studied following i. v. (12.5 mg in 1 h) and p. o. (50 mg) administration of racemic carvedilol in ten healthy male subjects according to a randomized crossover design. The AUCs ofS (−)-CARV were significantly lower than those ofR (+)-CARV after both i. v. and p. o. administration. The systemic clearance of the two enantiomers was significantly different, whereas half-lives and apparent distribution volumes were comparable. Following p. o. administration, the absolute bioavailability (31.1% and 15.1%, respectively) and maximal plasma concentrations ofR (+ )-CARV were twice those ofS (−)-CARV A similar difference was found in the half-lives. A close correlation existed between enantiomeric ratios after i.v. and after p. o. administration, demonstrating slight intraindividual variability. The preferential systemic clearance of theS ( − )-enantiomer suggests stereoselective hepatic metabolism of carvedilol, becoming especially apparent after p. o. administration. The small intrasubject variability in enantiomer ratios indicates a relatively constant relation of beta-blockade to vasodilation during chronic treatment.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 33 (1987), S. 511-513 
    ISSN: 1432-1041
    Keywords: carvedilol ; BM 14.190 ; pharmacokinetics ; bioavailability ; dose-linear kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The pharmacokinetics and absolute bioavailability of carvedilol have been studied in 20 male healthy volunteers in a randomised 4-period, cross-over trial. Carvedilol 12,5 mg was given i.v., 50 mg was administered p.o. as a suspension and 25 and 50 mg were given in a capsule formulation. For the 50 mg capsule Cmax was 66 µg·l−1, tmax 1.2 h, t1/2 6.4 h. The t1/2 after i.v. administration was 2.4 h, CL 589 ml/min and Vz 132 l. The absolute bioavailability was 24% (50 mg capsule). The kinetics after the 25 and 50 mg capsules were consistent with dose linearity.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Journal of Chromatography B: Biomedical Sciences and Applications 413 (1987), S. 355-362 
    ISSN: 0378-4347
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Journal of Chromatography B: Biomedical Sciences and Applications 422 (1987), S. 346-352 
    ISSN: 0378-4347
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Tetrahedron Letters 14 (1973), S. 1553-1556 
    ISSN: 0040-4039
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Tetrahedron Letters 14 (1973), S. 1549-1552 
    ISSN: 0040-4039
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Fatigue & fracture of engineering materials & structures 20 (1997), S. 0 
    ISSN: 1460-2695
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract— Measurements of CTODi on Charpy-V-specitnens of mild steel St 37 and pressure-vessel steel 22NiMoCr37 have been carried out. Slotted and precracked specimens have been used besides the original V-notched ones. A definition of CTOD = 2(R – Ro) has been proposed which corresponds to δ45, defining the CTOD of fatigue cracks. The symbols Ro and R represent the original and the actual crack tip radii respectively. Additionally, this definition presents the opportunity to measure CTOD and CTODi by a direct metallographic method. It is demonstrated that COD testing, based on the hinge model, can also be applied to slotted bars, delivering CTOD and CTODi values which are equal to those evaluated by direct metallographic measurements.The results obtained on four different tip radii, Ro, show a linear increase of CTODi as a function of Ro, which is steeper for the softer material St 37. The extrapolation to the tip radius Ro=0 gives a CTODi, which is equal to those determined from precracked specimens.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1432-0827
    Keywords: Key words: Bisphosphonates — Estrogens — Conjugates — Osteoporosis therapy.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract. In order to target 17β-estradiol directly at bone we synthesized three 17β-estradiol-bisphosphonate conjugates (E2-BPs) with different esterase-sensitive linkers between both molecular moieties. The systemic administration of these compounds should result primarily in local estrogenic effects on bone with no or negligible systemic hormonal effects. Only if a considerable margin exists between the doses required for inhibition of bone loss and those for systemic hormonal effects can such a pro-drug be considered acceptable for patients refusing systemic estrogen replacement therapy for several reasons. The conjugates were tested in vitro for their 17β-estradiol release in rat serum and in vivo for their local and systemic effects in rats: in vitro, the conjugates expressed cleavage resistance, low cleavage (4.8%), or high cleavage (33.1%) within 48 hours of incubation. The conjugate with the low-cleavage doubled 17β-estradiol serum half-life (3.78 hours) whereas the high-cleavage conjugate resulted in approximately four times higher serum half-life (8.36 hours) when compared with free 17β-estradiol. In ovariectomized rats, bone loss was optimally prevented by 50 nmol/kg/day of 17β-estradiol when administered S.C. over a period of 5 weeks, and protection against uterine atrophy was achieved at doses as low as 5 nmol/kg/day. The cleavage-resistant conjugate was ineffective in preserving bone and uterus in doses ranging from 5 to 150 nmol/kg/day. The other two E2-BPs revealed a dose-dependent inhibition of bone loss which was paralleled by the respective uterus weight with a dose range of 1.5–150 nmol/kg/day being fully effective in a range similar to 17β-estradiol alone. The higher sensitivity of the uterus versus bone to protective estrogenic effects (1:10) was abolished by the conjugates. We conclude that E2-BPs containing esterase-sensitive linkers failed to act as bone-seeking pro-drugs expressing primarily local effects on bone without systemic effects.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Archives of dermatological research 205 (1957), S. 53-64 
    ISSN: 1432-069X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
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