0000000000256445
AUTHOR
U. Groth
Interruption of the enterohepatic circulation of phenprocoumon by cholestyramine
The effect of cholestyramine (12 gm/day divided into 3 doses) on the pharmacokinetics and pharmacodynamics of a single intravenouse dose (30 mg) of phenprocoumon was studied in 6 normal subjects. Cholestyramine treatment led to an increase in the rate of elimination of phenprocoumon in all. Total clearance increased 1.5- to 2-fold. The total anticoagulant effect per dose was considerably reduced during treatment with cholestyramine. Binding studies in vitro showed that phenprocoumon is strongly bound to cholestyramine and that at a given cholestyramine concentration the percentage of phenprocoumon bound remained constant over a large concentration range of phenprocoumon. The results suggest…
Pharmacokinetic analysis of the interaction between dicoumarol and tolbutamide in man
The effect of repeated administration of tolbutamide on the elimination and anticoagulant action of a single oral dose of dicoumarol 600 mg was studied in four healthy male subjects using a crossover design. In all subjects the plasma concentration of dicoumarol in the postabsorptive phase was lower during concomitant tolbutamide treatment. However, the subjects differed with respect to the elimination kinetics of dicoumarol and the effect of tolbutamide on some of the measured pharmacokinetic paramaters. In two subjects dicoumarol was eliminated by apparent first-order kinetics. Tolbutamide led to a pronounced increase in the elimination rate and a shift in the plasma concentration-respons…
The enantiomers of phenprocoumon: pharmacodynamic and pharmacokinetic studies.
The pharmacodynamics and pharmacokinetics of the optical enantiomers of phenprocoumon were studied in 5 normal subjects and compared to the racemic mixture. Each subject received a single oral dose of 0.6 mg/kg of racemic, S(-), and R(+) phenprocoumon. S(-) phenprocoumon was 1.6 to 2.6 times as a potent as R(+) phenprocoumon when the area under the effect/time curve was used to quantify the total anticoagulant effect per dose. Comparing the plasma concentrations that elicited the same anticoagulant effect, S(-) phenprocoumon was 1.5 to 2.5 times as potent as R(+) phenprocoumon. The anticoagulant activity of the racemic mixture was between that of the enantiomers. There was no distinct diffe…
Vitamin A (Retinol) und Retinolbindendes-Protein (RBP) im Serum bei Maldigestion, Malabsorption und Lebercirrhose
Bei Normalpersonen und Patienten mit Malabsorption, Maldigestion und Lebercirrhose wurden vor und nach oraler Belastung mit 600 000 E Vitamin-A-palmitat bzw. wasserloslichem Vitamin A im Serum der Spiegel des Vitamin A (Retinol), des Retinol-bindenden Proteins (RBP) und Praealbumin bestimmt. In der Kontrolle steigt das Retinol nach Belastung signifikant an und erreicht nach 5 Std sein Maximum. Das RBP liegt im Mittel bei 42,25 mg/L, der Praealbuminspiegel bei 400 mg/L. Patienten mit Malabsorption und Lebercirrhose zeigen vor und nach Belastung mit Vitamin-A-palmitat einen gegenuber der Kontrolle verminderten Retinolspiegel. In der Gruppe der Maldigestion ist der Nuchternspiegel des Retinols…
Zur Vitalitätsprüfung isolierter Rattenleberzellen
Rattenleberzellen wurden mittels extrakorporaler Leberperfusion unter Verwendung eines Hyaluronidase-Kollagenase-haltigen bzw. enzymfreien Perfusionsmediums isoliert. Die isolierten Leberzellen wurden auf ihr Verhalten gegenuber Trypanblau, FDA, in der Phasenkontrastbetrachtung und im Luciferin-Luciferase-Test untersucht. Daruber hinaus wurde der ATP-Gehalt der Zellen sowie die spontane Abgabe von51Cr aus markierten Zellen bestimmt.