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  • bioavailability  (88)
  • Springer  (88)
  • 1
    Electronic Resource
    Electronic Resource
    Pulmonary Bioavailability of a Phosphorothioate Oligonucleotide (CGP 64128A): Comparison with Other Delivery Routes (1998)
    Springer
    Pharmaceutical research 15 (1998), S. 583-591 
    Details
    ISSN: 1573-904X
    Keywords: administration ; antisense ; bioavailability ; gastrointestinal ; intra-peritoneal ; intra-tracheal ; ISIS 3521 ; oligonucleotide ; oral ; pharmacokinetics ; subcutaneous
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. Phosphorothioate antisense oligodeoxynucleotides are promising therapeutic candidates. When given systemically in clinical trials they are administered via slow intravenous infusion to avoid their putative plasma concentration-dependent haemodynamic side-effects. In this study, we have evaluated alternative parenteral and non-parenteral administration routes which have the potential to enhance the therapeutic and commercial potential of these agents. Methods. The delivery of CGP 64128A by intravenous, subcutaneous, intra-peritoneal, oral and intra-tracheal (pulmonary) routes was investigated in rats using radiolabelled compound and supported by more specific capillary gel electrophoretic analyses. Results. Intravenously administered CGP 64128A exhibited the rapid blood clearance and distinctive tissue distribution which are typical for phosphorothioate oligodeoxynucleotides. Subcutaneous and intra-peritoneal administration resulted in significant bioavailabilities (30.9% and 28.1% over 360 min, respectively) and reduced peak plasma levels when compared with intravenous dosing. Administration via the gastrointestinal tract gave negligible bioavailability (〈2%). Intra-tracheal administration resulted in significant but dose-dependent bioavailabilities of 3.2, 16.5 and 39.8% at 0.06, 0.6 and 6.0 mg/kg, respectively. Conclusions. Significant bioavailabilities of CGP 64128A were achieved following subcutaneous, intra-peritoneal and intra-tracheal administration. Pulmonary delivery represents a promising mode of non-parenteral dosing for antisense oligonucleotides. The dose-dependent increase in pulmonary bioavailability suggests that low doses may be retained in the lungs for local effects whereas higher doses may be suitable for the treatment of a broader spectrum of systemic diseases.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1011934011690
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  • 2
    Electronic Resource
    Electronic Resource
    Human pharmacokinetics and bioavailability of temazepam administered in soft gelatin capsules (1977)
    Springer
    European journal of clinical pharmacology 12 (1977), S. 383-386 
    Details
    ISSN: 1432-1041
    Keywords: Benzodiazepine ; temazepam ; pharmacokinetics ; bioavailability ; hard and soft gelatine capsules
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Plasma levels of temazepam were determined in healthy subjects after single oral administration of soft and hard gelatin capsules, and after 7 consecutive night-time doses in soft capsules. Absorption from soft gelatin capsules was significantly faster and produced earlier and higher peak plasma levels. The two pharmaceutical forms did not show any significant difference in relative availability. The apparent half-life of temazepam after night-time administration was significantly shorter than after morning administration, but no change in half-life was observed between the first and seventh night-time doses.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00562455
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  • 3
    Electronic Resource
    Electronic Resource
    Absence of a significant pharmacokinetic interaction between hydrochlorothiazide and triamterene when coadministered (1984)
    Springer
    Journal of pharmacokinetics and pharmacodynamics 12 (1984), S. 575-586 
    Details
    ISSN: 1573-8744
    Keywords: hydrochlorothiazide ; triamterene ; hydroxytriamterene sulfate ; pharmacokinetics ; bioavailability ; renal clearance ; interaction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Hydrochlorothiazide, triamterene, and hydroxytriamterene sulfate were monitored in the plasma and urine of 24 healthy young men taking single doses of a liquid preparation containing both hydrochlorothiazide and triameterene, liquid preparations containing either of these drugs alone, and a combination tablet recently formulated with a dose ratio of hydrochlorothiazide: triamterene (1∶1,5) found to give optimal potassium-sparing effect. In contradiction to a recent publication, no interaction between the drugs affecting the bioavailability or renal clearance of either could be demonstrated. The previous report of drug-drug interaction probably arose from formulationrelated problems with bioavailability from the two capsule and two tablet products which had been studied. A well-formulated hydrochlorothiazide-triamterene combination tablet promotes plasma concentrations and urinary excretion of hydrochlorothiazide, triamterene, and hydroxytriamterene sulfate which are virtually identical to those seen after either a combination liquid dosage form or simple liquid forms containing only one of the two drugs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01059553
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  • 4
    Electronic Resource
    Electronic Resource
    Absolute bioavailability of an aqueous solution of 1-deamino-8-D-arginine vasopressin from different regions of the gastrointestinal tract in man (1993)
    Springer
    European journal of clinical pharmacology 44 (1993), S. 473-476 
    Details
    ISSN: 1432-1041
    Keywords: dDAVP ; bioavailability ; gastrointestinal tract ; healthy volunteers ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The absolute bioavailability of an aqueous solution of 1-deamino-8-D-arginine vasopressin (dDAVP) from different regions of the gastrointestinal (GI) tract (stomach, duodenum, jejunum, ileum, colon, rectum) has been studied in 6 healthy, male volunteers aged 24 to 35 years, followed for 12 h after each drug administration. For i. v. administration the subjects received 4 μg dDAVP. For intestinal administration 400 μg dDAVP was directly applied to six distinct sites in the GI tract via two or four channel tubes with or without a distal occlusive balloon. Biological effects were assessed and plasma and urinary levels of dDAVP were measured using a specific, sensitive RIA. Urine osmolality remained elevated and diuresis decreased for 12 h following dDAVP administration irrespective of the site of application. After i. v. administration, the half-life of elimination of dDAVP was 60.0 min, plasma clearance 1.7 ml·min−1·kg−1, amount excreted in urine 2.0 μg and renal clearance was 0.8 ml·min−1·kg−1. The mean bioavailability (f) after gastric application was 0.19% (range 0.02–0.35%). f was 0.24% after duodenal application (range 0.04–0.62%), 0.19% after jejunal (range 0.01–0.41%), 0.03% after distal ileal (range 0.01–0.08%), 0.04% after proximal colonic (range 0.01–0.12%) and 0.04% after rectal (0.01–0.10%) application. The bioavailability was significantly higher in the three upper GI regions in comparison to the three lower regions. The bioavailability of dDAVP after gastric, duodenal and jejunal application was similar to that after swallowing a tablet in a previous study. Absorption from the ileum was lower than expected and no preferential site of absorption was found.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00315546
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  • 5
    Electronic Resource
    Electronic Resource
    Receptor binding assays in analysing the bioavailability and pharmacodynamic bioequivalence of active drug moieties (1994)
    Springer
    European journal of clinical pharmacology 46 (1994), S. 237-242 
    Details
    ISSN: 1432-1041
    Keywords: Metoprolol ; bioavailability ; bioequivalence ; receptor binding assay ; pharmacokinetics ; sustained release formulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract The bioavailability and pharmacodynamic bioequivalence of a conventional and an experimental sustained-release formulation of 100 mg metoprolol tartrate were studied in a randomised cross-over study in seven healthy volunteers by assessing over 24 h the plasma kinetics of R,S-metoprolol, its β1-adrenoceptor binding component, and by determining the extent to which the active drug moiety in plasma occupied rabbit lung β1-and rat reticulocyte β2-adrenoceptors. The formulations differed markedly in their kinetic characteristics: the peak plasma concentration (Cmax) of R,S-metoprolol after administration of the conventional formulation was 140 ng·ml−1, (n=7) and it was approximately one-third of that after the sustained-release formulation, 49 ng·ml−1, (n=6); the AUC0–24 h-values for the formulations were 700 and 310 ng·h·ml−1, respectively. The Cmax for the β1-adrenoceptor binding component of metoprolol was 180 ng·ml−1 (n=7) after administration of the conventional, and 74 ng·ml−1 after administration of the sustained-release formulation. The corresponding AUC0–24 h-values for the receptor binding component were 920 and 470 ng·h·ml−1 (n=7). Thus, the kinetic differences between R,S-metoprolol and the β1-receptor binding component were considerable and they were affected by the type of formulation. In general, after administration of the sustained-release formulation, the percentage β1- and β2-adrenoceptor occupancy of metoprolol in plasma was 5–15% less than after administration of the conventional formulation. At 0.5–1.5 h after drug intake the average β1-adrenoceptor occupancy of the conventional formulation varied between 80–90% and that of the sustained release formulation between 20–76%. At these times the differences in receptor occupancy were significant; at 0.5–2 h after drug intake the average β2-adrenoceptor occupancy of the conventional formulation varied from 20–30%, and that of the sustained-release formulation was 2–17%. At other times the difference in receptor occupancy between the formulations was not significant. The results demonstrate that plasma concentration-kinetics were more discriminating than β-adrenoceptor-binding in analysing bioequivalence. It was possible to determine the bioavailability of the active ingredient of metoprolol and to study pharmacodynamic bioequivalence by using receptor binding assays.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00192555
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  • 6
    Electronic Resource
    Electronic Resource
    Conventional and controlled release diltiazem (1994)
    Springer
    European journal of clinical pharmacology 47 (1994), S. 75-79 
    Details
    ISSN: 1432-1041
    Keywords: Diltiazem ; Angina pectoris ; controlled release formulation ; metoprolol ; bioavailability ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract Diltiazem CR tablets 120 mg b.i.d. for 1 week were compared with plain tablets 60 mg q.i.d. in 13 healthy male volunteers in a study of pharmcokinetic variables. Their antianginal efficacy was also compared in 23 patients with stable angina pectoris who were already on metoprolol. Both studies were of randomised, cross over design, and the clinical study was double blind. The pharmacokinetic variables of the two formulations were very similar except for the longer tmax of 4.4 h for diltiazem CR in comparison to 2.9 h for the plain tablets. The mean relative bioavailability of diltiazem CR in comparison with plain tablets was 1.14. The clinical study showed that after four weeks on diltiazem CR 120 mg b.i.d. or diltiazem plain tablets 60 mg q.i.d. in addition to metoprolol, there were significant decreases in weekly anginal attacks from 11 to 5 attacks/week, the number of nitroglycerin tablets consumed from 6 to 3 tablets/week, and an increase in the maximum workload from 116 to 126 and 123 W for diltiazem CR and plain diltiazem tablets, respectively, as compared to placebo. Five of the patients were angina free during diltiazem treatment. No difference in antianginal efficacy between the two preparations was seen. It was concluded that CR 120 mg b.i.d. appears bioequivalent to plain diltiazem tablets 60 mg q.i.d.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00193483
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  • 7
    Electronic Resource
    Electronic Resource
    Temperature dependency of the release and bioavailability of nicotine from a nicotine vapour inhaler; in vitro/ in vivo correlation (1997)
    Springer
    European journal of clinical pharmacology 52 (1997), S. 495-500 
    Details
    ISSN: 1432-1041
    Keywords: Key words Nicotine ; vapour inhaler ; bioavailability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract Objective: To investigate the temperature dependency of the dose released and the plasma levels of nicotine from a vapour inhaler. Methods: In an open, randomised, three-way cross-over pharmacokinetic study 18 healthy subjects inhaled nicotine for 20 min (80 inhalations) every hour for 10 h (11 administrations) at three different environmental temperatures: 20°, 30° and 40 °C. In the in vitroexperiment, 5, 10, 15 and 20 l air were forced through the inhaler. With a 15 l air volume, the average amount of nicotine released was 1.44, 3.49, 4.80 and 6.99 mg at 10 °C, 22 °C, 29 °C and 40 °C, respectively. The maximum dose released at the highest temperature (40 °C) and the largest air volume investigated (20 l) was approximately 7.5 mg. Results: In vivo peak plasma levels obtained at 30° and 40 °C were 29.7 and 34.0 ng · ml−1, compared with 22.5 ng · ml−1 at ambient room temperature (20 °C). At 20 °C, the area under the plasma concentration–time curve (AUC) of the last dosing interval was 20.5 ng · ml−1 · h. At 30 °C and 40 °C, the AUCs were 26.5 and 30.3 ng · ml−1 · h, respectively. The results thus showed a mean increase of the in vivo AUC by 29% at 30 °C and by 48% at 40 °C compared with the AUC at 20 °C. These increases should be compared to the in vitro results, showing a mean increase of 59% and 122%, respectively, at 30° and 40 °C. The in vitro results also showed that a relatively larger fraction of the dose was released into the first 5 l of air at the higher temperatures, at 40 °C, about 50% of the total amount released into 20 l. Conclusion: It was concluded that the in vitro/in vivo discrepancy was most probably due to increased aversive effects at elevated temperatures, causing the subjects to inhale smaller puff volumes. Further, the inhaler would not produce nicotine plasma levels exceeding those achieved following cigarette smoking, even in a hot climate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002280050324
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  • 8
    Electronic Resource
    Electronic Resource
    Pharmacokinetics of xamoterol after intravenous and oral administration to volunteers (1988)
    Springer
    European journal of clinical pharmacology 34 (1988), S. 469-473 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01046704
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  • 9
    Electronic Resource
    Electronic Resource
    Pharmacokinetics of midazolam in children: comparative study of intranasal and intravenous administration (1991)
    Springer
    European journal of clinical pharmacology 41 (1991), S. 355-357 
    Details
    ISSN: 1432-1041
    Keywords: Midazolam ; pharmacokinetics ; intranasal ; intravenous ; children ; bioavailability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Twelve children 1–5 y old were randomly assigned to receive midazolam 0.2 mg·kg−1 either by the intravenous (IV) or intranasal (IN) routes. After IN administration the rapid onset of absorption was observed (tmax 12 min). After both routes of administration the half-life was similar (2.2 h IN and 2.4 h IV). After IN administration the apparent plasma clearance and volume of distribution were about twice as high as after IV administration. The results are consistent with an estimated mean bioavailability of 55%.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00314967
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  • 10
    Electronic Resource
    Electronic Resource
    Single dose pharmacokinetics of sumatriptan in healthy volunteers (1995)
    Springer
    European journal of clinical pharmacology 47 (1995), S. 543-548 
    Details
    ISSN: 1432-1041
    Keywords: Sumatriptan ; pharmacokinetics ; single dose ; bioavailability ; dose proportionality ; healthy volunteers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract Sumatriptan is classified as a vascular 5HT1 receptor agonist and is effective in the acute treatment of migraine and cluster headache. Sumatriptan is available as an injection for subcutaneous administration and as a tablet for oral administration. The pharmacokinetics of sumatriptan differ depending on the route of administration. The mean subcutaneous bioavilability is 96% compared to 14% for the oral tablet. The lower bioavailability following oral administration is due mainly to presystemic metabolism. The inter-subject variability in plasma sumatriptan concentrations is greater following oral administration and a faster rate of absorption of drug into the systemic circulation is achieved following subcutaneous dosing. The pharmacokinetics of sumatriptan are linear up to a subcutaneous dose of 16 mg. Following oral dosing up to 400 mg, the pharmacokinetics are also linear, with the exception of rate of absorption, as indicated by a dose dependent increase in time to peak concentration. Sumatriptan is a highly cleared compound that is eliminated from the body primarily by metabolism to the pharmacologically inactive indoleacetic acid analogue. Both sumatriptan and its metabolite are excreted in the urine. Although the renal clearance of sumatriptan is only 20% of the total clearance, it exceeds the glomerular filtration rate, indicating that sumatriptan undergoes active renal tubular secretion. Sumatriptan has a large apparent volume of distribution (170 1) and an elimination half-life of 2 h. Oral doses of sumatriptan were administered as a solution of dispersible tablets and subcutaneous dosing was by injection into the arm. In clinical practice, sumatriptan is administered as a film coated tablet or by subcutaneous injection into the thigh.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00193709
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