[Enteral resorption and bioavailability of norfenefrine].
Four volunteers received orally an aqueous solution of 4.5 mg of 14C norfenefrine. Urine was collected for the following 24 h and assayed for unchanged drug and metabolites. Blood was drawn for the determination of free norfenefrine at frequent intervals over an 8-h period. The highest serum levels of free norfenefrine were seen 30-60 min after ingestion with an average of 2 ng/ml. The half-lives ranged from 163-402 min. The cumulative urinary excretion of 14C radioactivity exceeded 90% of the dose, more than 50% being conjugated norfenefrine. As result of the area under the plasma level curve bioavailability has to be set at 20% when compared to other sympathomimetic amines. The result in our patient with porto-caval anastomosis did not differ from normal. Thus, the significance of the gut wall as the site of conjugation during the first-pass is demonstrated.
D015078:2-Hydroxyphenethylamine / Q000378:metabolism*; D000284:Administration, Oral; D001682:Biological Availability; D006801:Humans; D007408:Intestinal Absorption; D008657:Metabolic Clearance Rate; D010627:Phenethylamines / Q000378:metabolism*
D010627:Phenethylamines; D015078:2-Hydroxyphenethylamine
Enterale Resorption und Bioverfügbarkeit von Norfenefrin.