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  • bioavailability  (223)
  • Springer  (223)
  • American Physical Society (APS)
  • International Union of Crystallography (IUCr)
  • 1985-1989  (93)
  • 1980-1984  (130)
Collection
Publisher
  • Springer  (223)
  • American Physical Society (APS)
  • International Union of Crystallography (IUCr)
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Year
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    European journal of nutrition 22 (1983), S. 185-194 
    ISSN: 1436-6215
    Keywords: sugar substitutes ; D-glucose ; bioavailability ; D-glucitol (D-sorbitol) ; D-mannitol ; Palatinit® ; D-glucosyl-α(1→1)-D-mannitol ; D-glucosyl-α(1→6)-D-glucitol
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Medicine
    Description / Table of Contents: Zusammenfassung Zur Vertiefung des Verständnisses vom Stoffwechsel des Zuckeraustauschstoffes Palatinit® wurden seine zwei Bestandteile D-Glucosyl-α(1→1)-D-mannit und D-Glucosyl-α(1→6)-D-glucit [D-Glucosyl-α(1→6)-D-sorbit] nach dem Verfahren von Karimzadegan et al. auf ihre Glucose-Bioverfügbarkeit an ketotischen Ratten untersucht. Bei Umwandlungsraten in Glucose von 6 bzw. 20 % für Mannit und Glucit (Sorbit) sowie von 39 bzw. 42% für Glucosylmannit und Glucosylglucit erhält demnach der metabolische Glucose-Pool nicht das volle Glucose-Äquivalent aus diesen Verbindungen. Von dem Anteil an präformierter Glucose in den Glucosylhexiten — theoretisches Maximum 50 % — sind nur 36 % aus Glucosylmannit bzw. 32 % aus Glucosylglucit bioverfügbar. Die im Vergleich zur Theorie verminderte Bioverfügbarkeit von Glucose aus Palatinit® wird auf partiellen mikrobiellen Abbau in unteren Darmabschnitten zurückgeführt. Die an Ratten erhaltenen Ergebnisse werden auch für alle anderen Spezies gelten, welche in Caecum und/oder Colon Kohlenhydrate vergären. Die Unterschiede zwischen D-Glucosyl-α(1→1)-D-mannit und D-Glucosyl-α(1→6)-D-glucit werden durch unterschiedliche Verzögerung der Glucoseresorption im Dünndarm, wo auch D-Glucit angreift, bedingt. Die Ermittlung der Glucose-Bioverfügbarkeit gewährt weitgehende Einblicke in das Schicksal von Kohlenhydraten einschließlich der Symbiose zwischen Säugetier und Mikroorganismen im Dickdarm. Da ein ziemlich vollständiger Überblick über die metabolischen Konsequenzen nach ihrer Zufuhr erhalten wird, sollte das Verfahren zur Messung der Bioverfügbarkeit von Glucose daher bei Abschätzungen der Lebensmittelsicherheit anderer Zuckeraustauschstoffe ebenfalls angewandt werden.
    Notes: Summary For the sake of metabolic insight into the fate of the sugar substitute Palatinit®, its two components D-glucosyl-α(1→1)-D-mannitol and D-glucosyl-α(1→6)-D-glucitol [D-glucosyl-α-(1→6)-D-sorbitol] were assayed for glucose bioavailability by the procedure of Karimzadegan et al. using ketotic rats. With conversion rates into glucose of 6 and 20 %, respectively, for free mannitol and glucitol (sorbitol), 39 % for glucosylmannitol and 42 % for glucosylglucitol, the metabolic glucose pool of the rat does not receive the full carbohydrate complement of these compounds. The preformed glucose moiety of the glucosylhexitols is bioavailable by 36 and 32 %, respectively, from glucosylmannitol and glucosylglucitol, with 50 % as theoretical maximum. Less than theoretical bioavailability of glucose from Palatinit® is ascribed to microbial attack in the hindgut. The data on rats are held valid also for other species demonstrating carbohydrate fermentation in the caecum and/or colon. Differences between D-glucosyl-α(1→1)-D-mannitol and D-glucosyl-α(1→6)-D-glucitol are caused by a differential delay of glucose absorption in the small intestine, also exerted by D-glucitol. The deep metabolic insight offered by the glucose bioavailability assay into the fate of carbohydrates includes the mammal-microbial symbiosis in the large bowel. Since a rather complete survey of the metabolic consequences after their intake can be obtained, the assay system should be generally applied in assessments of food safety also of other sugar substitutes.
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    European journal of nutrition 28 (1989), S. 130-141 
    ISSN: 1436-6215
    Keywords: bioavailability ; folic acid ; pharmaceutical preparation ; Bioverfügbarkeit ; Folsäure ; Arzneimittelzubereitung
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Medicine
    Description / Table of Contents: Zusammenfassung Untersuchungen zur Bioverfügbarkeit essentieller Mikronährstoffe (Vitamine, Mineralstoffe, Spurenelemente) aus Lebensmitteln wie auch aus Arzneimittelzubereitungen sind von entscheidender Bedeutung bei der Beurteilung des jeweiligen Beitrages zur Nährstoffversorgung bzw. zur Abschätzung eines möglichen Therapieerfolges. Die Durchführung derartiger Prüfungen erfolgt in der Praxis nicht selten nach unterschiedlichen Kriterien. Deshalb werden zunächst die Grundsätze erläutert, die bei entsprechenden Prüfungen für eine valide Bewertung von Nähr- bzw. Wirkstoffgemischen oder Monopräparaten bedeutsam sind. Abschließend wird die Ermittlung der Bioverfügbarkeit von Folsäure an einem Beispiel demonstriert. Zur Testung werden die postresorptiven Kurvenintegrale ermittelt, wobei die Daten auf das basale Ausgangsniveau bezogen werden. Zur Beurteilung der Bioverfügbarkeit findet neben dem maximalen Vitaminanstieg im Serum sowie der Zeit bis zum Konzentrationsmaximum insbesondere der Bioverfügbarkeitsquotient von Test- und Referenzzubereitung mit seinem 95%-VB Berücksichtigung. Die Ergebnisse zeigen, daß die exemplarisch eingesetzte Testsubstanz, 5-Formyl-Tetrahydrofolsäure, eine sehr gute Bioverfügbarkeit aufweist und daß unter Anwendung der beschriebenen Rahmenbedingungen eine objektive Bewertung der Bioverfügbarkeit möglich ist.
    Notes: Summary Bioavailability studies of micronutrients (vitamins, minerals) from different food stuffs, as well as from pharmaceutical preparations are of great importance for the calculation of nutrient intake and/or the evaluation of the therapeutic value. In practice, bioavailability studies are not generally performed on a standardized level. For this reason basic criterions are presented and discussed. Finally, the investigation of the bioavailability of folate is demonstrated by an example. The parameters investigated are: the maximal concentration (cmax), the time to reach this maximum (tmax), and especially the bioavailability ratio determined from the area under the curve (AUC) after administration of the folic acid containing test and reference preparation. The results indicate that 5-formyl-tetrahydrofolic acid given in the tested form has nearly the same bioavailability (ratio: 1.02) as folic acid (pteroylmonoglutamic acid) in aqueous solution.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 32 (1987), S. 631-634 
    ISSN: 1432-1041
    Keywords: salbutamol ; albuterol ; pharmacokinetics ; bioavailability ; healthy volunteers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Salbutamol was administered to sixteen healthy male volunteers intravenously and by mouth in liquid, tablet, and capsule form using a Latin-Squares design. Pharmacokinetic parameters from intravenous data were similar to previously reported values obtained with oral administration, with a mean terminal half-life of 3.8 h and a mean clearance of 439 ml·min−1·1.73 m−2. Peak plasma concentrations of 10–20 ng·ml−1 were obtained 1–3 h following oral administration. The absolute bioavailability of each of the oral preparations was 44%. While statistically significant differences in lag time and time to peak concentration were noted among the various oral preparations, the drug is rapidly absorbed in all three dosage forms and the observed differences are unlikely to be of clinical significance.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 34 (1988), S. 77-82 
    ISSN: 1432-1041
    Keywords: N-acetylcysteine ; pharmacokinetics ; bioavailability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The pharmacokinetics and bioavailability of N-acetylcysteine (NAC) have been determined after its intravenous and oral administration to 6 healthy volunteers. According to a randomized cross-over design each subject received NAC 200 mg i.v. and 400 mg p.o., and blood samples were collected for 30 h. Reduced NAC had a volume of distribution (VSS) of 0.59 l·kg−1 and a plasma clearance of 0.84 l·h−1·kg−1. The terminal half-life after intravenous administration was 1.95 h. The oral bioavailability was 4.0%. Based on total NAC concentration, its volume of distribution (VSS) was 0.47 l·kg−1 and its plasma clearance was 0.11 l·h−1·kg−1. The terminal half-life was 5.58 h after intravenous administration and 6.25 h after oral administration. Oral bioavailability of total NAC was 9.1%.
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 34 (1988), S. 315-317 
    ISSN: 1432-1041
    Keywords: albendazole ; echinococcosis ; bioavailability ; food intake ; fatty meal
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary We have studied the systemic availability of oral albendazole in 6 patients with echinococcosis either fasting or with breakfast. Albendazole sulphoxide, the pharmacologically active principle, was assayed by HPLC. Mean plasma concentrations and AUCs were 4.5 times higher when albendazole was given with breakfast than when administered in the fasting state. We conclude that therapy of echinococcosis with albendazole requires the drug to be taken with meals and that administration on an empty stomach might be more appropriate when intraluminal effects are desired, e.g. for intestinal parasites.
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 34 (1988), S. 469-473 
    ISSN: 1432-1041
    Keywords: xamoterol ; cardiac failure ; beta1-adrenoceptor partial agonist ; pharmacokinetics ; bioavailability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The pharmacokinetics of xamoterol, a β-adrenoceptor partial agonist under clinical evaluation for the treatment of mild to moderate heart failure, have been studied in 12 healthy male subjects. They received 14 mg i.v. and oral doses of 50 and 200 mg as a tablet and 200 mg as a solution in a 4 way cross-over design. After i.v. dosing the elimination half-life was 7.7 h, the total body clearance was 224 ml·min−1 and the volume of distribution at steady-state (Vss) was 48 l. Sixty-two percent of the dose was recovered unchanged in urine. After oral doses, the absolute bioavailability of xamoterol was shown to be 5% irrespective of whether the dose was administered as a tablet or solution. Peak plasma concentrations occurred at about 2 h for the tablet dose and slightly earlier (1.4 h) for the solution. Peak plasma concentration, AUC and urinary recovery of unchanged drug increased in proportion to dose. The apparent elimination half-life after oral doses (16 h) was significantly longer than that observed after an intravenous dose. Despite the low bioavailability, the degree of inter-subject variability of oral bioavailability was small probably indicating that the controlling factor is the hydrophilic nature of the molecule rather than extensive first pass metabolism or poor dissolution of xamoterol from the tablet formulation.
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 32 (1987), S. 625-629 
    ISSN: 1432-1041
    Keywords: disopyramide ; bioavailability ; saturable binding ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The pharmacokinetics of disopyramide were determined in 10 healthy volunteers after a 300 mg oral dose and again after a 2mg/kg i.v. dose. The unbound clearance was 599 ml/min and the unbound renal clearance 310 ml/min. The terminal elimination rate constant of unbound drug was 0.180 h−1 after the i.v. dose and 0.203 h−1 after the oral dose. The absorption rate constant was 0.53−1 and the maximum peak concentration occurred after 3.2 h. The bioavailability was 0.809 using the area under the unbound plasma concentration time curve. Although a saturable plasma protein binding was found in all subjects the bioavailability using the total concentration, in contrast to theoretical expectations, showed the same value (0.813) as the unbound concentrations.
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 34 (1988), S. 211-212 
    ISSN: 1432-1041
    Keywords: diclofenac ; sulglicotide ; bioavailability ; drug interaction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The bioavailability of diclofenac (D) was assessed in 12 healthy volunteers treated orally with single doses of 100 mg (retard formulation) and subsequently retreated with the same dose of (D) plus sulglicotide (S) 200 mg. (D) blood levels were measured by GLC in samples collected after 1, 2, 4, 6, 8, 12, 24 h. No relevant difference was seen in (D) bioavailability after (S) administration; after 8 h plasma levels of (D) were slightly higher after (S) (p〈0.05), but this difference can be considered incidental only. Thus, sulglicotide does not interfere with the bioavailability of diclofenac, and can be administered concurrently with the latter to prevent possible gastric injury by the antiinflammatory drug.
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 35 (1988), S. 21-24 
    ISSN: 1432-1041
    Keywords: doxazosin ; hypertension ; alpha-adrenergic blockade ; bioavailability ; pharmacokinetics ; adverse effects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The antihypertensive effects and steady-state pharmacokinetics of doxazosin, as well as the bioequivalence of four dosage forms, were studied in 25 hypertensive patients. For an 8 mg daily dose mean Cmax at steady-state for all patients was 108 ng/ml; the mean tmax was 1.8 h. The mean terminal elimination half-life was 22 h. The four tablets containing 1, 2, 4, or 8 mg of doxazosin were bioequivalent in delivering the 8 mg dose. In patients with mild to moderate hypertension, 26-day treatment with doxazosin resulted in blood pressure reduction of 10/7 mm Hg in the supine and 13/18 mm Hg in the standing position. Adverse effects were generally mild and of brief duration.
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 35 (1988), S. 69-75 
    ISSN: 1432-1041
    Keywords: L-carnitine ; pharmacokinetics ; intravenous and oral doses ; bioavailability ; healthy volunteers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The pharmacokinetics of single intravenous and oral doses of L-carnitine 2 and 6 g was studied in 6 healthy subjects on a low-carnitine diet. Carnitine was more rapidly eliminated from plasma after the 6 g dose. Comparing the doses, the t1/2β of the elimination phase (β) was 6.5 h vs 3.9 h, the elimination constant 0.40 vs 0.50 h−1 and the plasma carnitine clearance was 5.4 vs 6.11 · h−1 for the 2 g and 6 g doses, respectively, showing dose-related elimination. Saturable kinetics were not found. The apparent volumes of distribution after the two doses were not significantly different and were of the same order as the total body water. Urinary recoveries of the 2 g and 6 g doses were 70% and 82%, respectively, during the first 24 h. Following the oral doses, there was no significant difference between the areas under the plasma carnitine concentration-time curves. Urinary recovery was 8% and 4% for the 2 g and 6 g doses during the first 24 h. Oral bioavailability was 16% for the 2 g dose and 5% for the 6 g dose. The results suggest that the mucosal absorption of carnitine was already saturated by the 2 g dose.
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