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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 8 (1975), S. 33-39 
    ISSN: 1432-1041
    Keywords: m-octopamine ; metabolism ; first-pass effect ; man ; enteric absorption ; monohydroxylated phenylalkylamines
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The diminished sympathomimetic pressor activity of monohydroxylated phenylalkylamines after oral administration has been attributed to incomplete enteric absorption. Therefore, urinary excretion of the unchanged drug and its metabolites has been compared after intravenous and oral administration of3H-m-octopamine to eight patients. Identical amounts of3H-activity (80% of the dose) were excreted after the two routes of dosing, so enteric absorption has been assumed to be complete. Significant differences were found in the fraction of free urinarym-octopamine, which amounted to 10.5% of the dose after infusion and 0.58% after oral administration. The only metabolic pathways form-octopamine are deamination and conjugation. Following oral administration the percentage of conjugates was considerably higher than after intravenous infusion. This metabolic pattern appears typical of all phenylalkylamines with a hydroxyl group in themeta position. Ring hydroxylation to catecholamines was not observed. The enzymes mainly responsible for conjugation after oral administration are located in the gut wall. The resulting “first pass effect”, i.e. metabolism prior to the access to the central compartment, can account for the diminished pharmacodynamic effect after dosing by this route.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 9 (1975), S. 179-187 
    ISSN: 1432-1041
    Keywords: Etilefrine ; pharmacokinetics ; metabolism ; first-pass effect
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Pharmacokinetic and metabolic studies with3H-etilefrine were performed to assess the importance of a first-pass effect on the pharmacodynamic action of this sympathomimetic amine. Identical amounts of3H-activity, ca. 80% of the dose, were excreted in the urine after intravenous or oral administration, which indicates complete enteral absorption of the drug. Comparison of the areas under the plasma curves of unchanged etilefrine after both routes of administration resulted in a bioavailability factor of 0.55, which can be explained by an extensive first-pass effect. The time curve of plasma levels of etilefrine was compatible with an open 2-compartment model characterized by a rather large volume of distribution (Vd, β) of 160 1, and a predominant half life of 2 hours. The pharmacodynamic action corresponded to the amount of drug in the central compartment. The major pathway of metabolism of etilefrine was conjugation to form the phenolic sulphate, and a very minor proportion of the drug was excreted as the corresponding hydroxymandelic acid. This metabolic pattern seems to confirm our hypothesis that phenylalkylamines with the hydroxyl group in the m-position of the benzene ring are predominantly conjugated in contrast to p-hydroxylated compounds which are mainly deaminated.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-0738
    Keywords: Cyclohexylamine ; Pharmacokinetics ; Pharmacodynamics ; Cyclamate ; Cyclohexylamin ; Pharmakokinetik ; Pharmakodynamik ; Cyclamat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Cyclohexylamin — ein Stoffwechselprodukt des künstlichen Süßstoffes Cyclamat — wurde in Dosen von 2,5, 5 und 10 mg/kg KG oral an gesunde Versuchspersonen verabreicht. Die Plasmahalbwertszeit von CHA betrug 3,5 bis 4,8 Std, wobei eine deutliche Abhängigkeit der Halbwertszeit von der applizierten Dosis beobachtet werden konnte. 86 bis 95% der verabfolgten Dosis wurden innerhalb 48 Std als unverändertes CHA im Urin ausgeschieden. Da Cyclohexylamin mit einem pKa von 10.6 eine stark basische Substanz ist, ist die fast vollständige enterale Resorption, ermittelt über die cumulative Urinausscheidung, als unerwartet hoch anzusehen. CHA verursachte einen dosisabhängigen Blutdruckanstieg, wobei eine enge Beziehung zwischen Blutdruckanstieg und den Cyclohexylaminplasmaspiegeln aufgestellt werden konnte. Auf Grund dieser Blutspiegel-Wirkungskurve konnte gezeigt werden, daß für einen signifikanten Blutdruckanstieg der kritische Cyclohexylaminplasmaspiegel zwischen 0,7 bis 0,8 μg/ml liegt. 10 mg/kg K.G. Cyclohexylamin verursachten einen signifikanten Anstieg der unveresterten Plasma-Fettsäuren und der cumulativen Katecholaminausscheidung im Harn, wohingegen Dosen von 2,5 und 5 mg/kg ohne Effekt waren. Diese Ergebnisse zeigen, daß CHA ein indirektes Sympathikomimetikum ist, das allerdings wesentlich weniger wirksam ist als verwandte sympathikomimetische Substanzen.
    Notes: Abstract Cyclohexylamine (CHA) a possible metabolite of the artificial sweetener cyclamate was administered orally in doses of 2.5, 5 and 10 mg/kg b.w. to healthy volunteers. Plasma half lives of CHA ranged from 3.5 to 4.8 h showing a clear dose dependency. 86 to 95 % of the dose administered was excreted in the urine during 48 h as unchanged drug. Since CHA is a fairly strong base with a pKa of 10.6 the almost complete enteral absorption was rather unexpected. Cyclohexylamine caused a dose dependent rise in arterial blood pressure. A close correlation between plasma levels of CHA and increase of mean arterial blood pressure could be established. The analysis of this concentration response curve revealed that plasma levels of CHA of about 0.7 to 0.8 μg/ml are required in order to cause a significant increase in arterial blood pressure. A significant increase in plasma free fatty acids and cumulative urinary excretion of catecholamines was observed only after the administration of 10 mg/kg b.w. CHA. Our findings are consistent with cyclohexylamine being an indirect acting sympathomimetic amine which is some orders of magnitude less potent than related sympathomimetic substances.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Journal of molecular medicine 55 (1977), S. 13-21 
    ISSN: 1432-1440
    Keywords: Digitalis intoxication ; Digoxin ; Lanatosid C ; Pharmacokinetics ; Digitalisintoxikation ; Digoxin ; Lanatosid C ; Pharmakokinetik
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung 6 Patienten mit einer schweren Digitalisintoxikation wurden stationär beobachtet. 2 Patienten hatten ein Lanatosid C-, 4 ein Digoxin-Präparat eingenommen. In 3 Fällen wurden ventrikuläre Extrasystolen, in einem dieser Fälle und bei zwei weiteren S-A-Blockierungen und in einem Fall zusätzlich eine A-V-Blockierung gesehen. Die maximalen Digoxinplasmaspiegel lagen zwischen 3,4 und 20 ng/ml. Bei einer Patientin war erst 52 h nach Einnahme von Lanatosid C und bei einer anderen 12,6 h nach der toxischen Dosis von Digoxin das Blutspiegelmaximum erzielt. Erhöhte Kaliumkonzentrationen im Plasma fanden sich bei 4 Patienten. Die antiarrhythmische Therapie und die Elektrolytbilanzierung werden diskutiert und die Nützlichkeit einer Magenspülung an dem Fall einer Patientin aufgezeigt, die nach der oralen Einnahme von 23,75 mg Lanatosid C nach rechtzeitig vorgenommener Magenspülung nur maximale Blutspiegel von 3,4 ng/ml aufwies. Die kumulative Ausscheidung von Digoxin in den Urin betrug bei dieser Patientin lediglich 0,68 mg in 5 1/2 Tagen und bestätigt eine minimale Absorption unter der vorgenommenen Therapie.
    Notes: Summary 6 patients with severe digitalis intoxication were studied while hospitalised in a coronary care unit. 2 and 4 patients had ingested high doses of lanatosid C and digoxin, respectively. In three cases ventricular arrhythmias, in one of these and two further cases SA blocking and an additional A-V-block in one case were observed. Maximum blood levels of digoxin between 3.4 and 20 ng/ml were determined several hours after the ingestion. The maximal blood levels were achieved in one patient only 52 h after ingesting lanatosid C and in one patient taking digoxin after 12.5 h. Potassium concentrations in plasma were elevated in 4 patients. Antiarrhythmic and electrolyte therapy is discussed and the usefulness of a stomach lavage for diminishing the quantity of absorbed lanatosid C is shown in one patient who had a maximal blood level of 3.4 ng/ml after taking 23.7 mg of lanatosid C. Cumulative urinary excretion of this patient was 0.68 mg within 5.5 days. This result confirms the minimal enteral absorption under the therapy chosen.
    Type of Medium: Electronic Resource
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