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  • 1
    ISSN: 1432-1041
    Keywords: prenalterol ; metoprolol ; haemodynamics ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The haemodynamic effects of the selectiveβ 1-adrenoceptor agonist prenalterol were studied in healthy subjects before and after therapeutic doses of the selectiveβ 1-adrenoceptor blocker metoprolol. Plasma levels of the drugs were also determined in order to calculate certain pharmacokinetic variables. Intravenous infusion of prenalterol 0.13, 0.25 and 0.50 mg induced a dose-dependent decrease in total electromechanical systole (QA2) and pre-ejection period (PEP). The effect on left ventricular ejection time (LVET) was not significant. Increases in systolic blood pressure and heart rate were dose-dependent. Diastolic blood pressure did not change significantly. When metoprolol had been administered in a cumulative dose of 150 mg (mean maximal plasma level, 284 nmol/1) prenalterol had to be administered in doses that were twelve times higher than before theβ-blocker in order to induce the same haemodynamic effects. Prenalterol was rapidly distributed with an average half life of 8 min. This indicates that distribution equilibrium will be achieved within 30 min after intravenous administration. The overall elimination rate in the post-distributive phase corresponded to an average half life of 2.0 h.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1573-904X
    Keywords: remoxipride ; modified release ; suspension ; bioavailability ; convolution ; deconvolution ; dissolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Remoxipride, a D2-dopamine receptor antagonist, is well tolerated and completely absorbed after oral administration. Because of its extremely bitter taste, an oral palatable suspension was developed by using a taste-masking microencapsulation. The bioavailability of remoxipride was investigated in two studies in healthy volunteers after administration of a 100-mg dose in suspension. The first study used a capsule as reference, and the second study a plain solution. Taste assessment was carried out in the second study. The extent of bioavailability was the same when comparing the oral suspension to a capsule and to a plain solution. However, the rate of absorption is delayed, and Tmax was 3.0 hr after the suspension, 1.0 hr after the oral solution, and 1.6 hr after the capsule. The release rate in vitro from the suspension was determined by applying the USP-paddle method. By using numerical convolution and deconvolution, the release rates in vivo and in vitro were shown to be similar when using water with 0.5% sodium lauryl sulfate as dissolution liquid. The taste-masked oral suspension is suitable for full-scale production, with good control of the encapsulation process and of the preparation of a suspension.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Journal of pharmacokinetics and pharmacodynamics 3 (1975), S. 69-76 
    ISSN: 1573-8744
    Keywords: intravenous procainamide hydrochloride ; healthy subjects ; rate of elimination and formation ofN-acetylprocainamide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Equations were derived which made it possible to determine the elimination rate of N -acetylprocainamide from urinary data after intravenous administration of procainamide hydrochloride. A single dose of 500 mg of the drug was infused intravenously in four healthy subjects. On the basis of those equations, the formation rate of the metabolite could be calculated presuming that all rate processes were occurring by first-order processes. However, close examination of the excretion rate data appears to support the contention that the formation or excretion of N -acetylprocainamide may be occurring by a saturable process.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Journal of pharmacokinetics and pharmacodynamics 12 (1984), S. 367-380 
    ISSN: 1573-8744
    Keywords: in vitro-in vivo correlation ; statistical moments ; MRT ; MDT in vitro ; MDT in vitro ; C max ; AUC ; alaproclate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract In two different absorption studies, quantitative correlations between the in vitro dissolution rate and the bioavailability have been shown after single administration of various tablet compositions of alaproclate hydrochloride to healthy subjects. Both statistical moment analysis and the use of empirical single value parameters were tested. For conventional tablets a linear relationship was obtained between mean dissolution time in vitro and in vivo. A similar relationship was obtained between the mean dissolution time in vitro and the mean residence time for controlled release tablets of the matrix type. It was also possible to establish an in vitro-in vivo correlation for these latter tablets by using the single point estimate of maximum plasma concentration as in vivo parameter. When comparing the mean dissolution time in vitro to the total area under the plasma drug concentration-time curve attained after different types of tablets, it is obvious that the extent of bioavailability of alaproclate will not fall below 80% of the value found for an aqueous solution until the mean dissolution time in vitro exceeds approximately 3 hr. Statistical moment analysis seems to have a broader applicability than the use of empirical point estimates, and it seems to be useful both for conventionally dissolving tablets and controlled release tablets.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1573-904X
    Keywords: remoxipride ; extended release ; gamma scintigraphy ; multiple-unit capsule ; absorption
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract To explore the oral absorption of remoxipride, spheres of remoxipride were labeled with indium-111 colloid before coating with a release-controlling ethylcellulose membrane. Since the labeling remained inside the coating, it was suitable as a marker. Eight healthy volunteers were given a single dose of 100 mg remoxipride in 111In-marked spheres as a multiple-unit capsule. The radioactivity and the position of the spheres (microcapsules) were followed externally for 30 hr by gamma scintigraphy. Parallel to this, plasma concentrations were drawn for 48 hr to confirm the extended dissolution and absorption of remoxipride. The hard gelatin, multiple-unit capsule released the microcapsules within the stomach. These were then rapidly emptied into the small intestine, within 0.5–1 hr. There was then an immediate distribution in the upper small intestine before collection in the lower portion, within 2–5 hr. After passing into the large intestine, there was again an extended distribution of the microcapsules. A mean C max of 2.7 µM remoxipride was achieved 4 hr after drug administration and a mean AUC of 26.1 µmol · L−1 hr was achieved. Judging from the absorption versus time profile, calculated according to the Wagner–Nelson method, and the scintigraphic images, it is concluded that the main absorption occurs from the small intestine. Data from four volunteers, however, indicated a comparatively good absorption also from the large intestine. Due to the good absorption properties, it is reasonable to expect a low variation in the extent of bioavailability of remoxipride after administration in an extended-release, multiple-unit capsule formulation.
    Type of Medium: Electronic Resource
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