The Gastrointestinal Absorption of Atropine in Man

Abstract

1. An aqueous solution of [3H]atropine (2 mg, 50 μCi) and polyethylene glycol (PEG, unabsorbable marker), was administered orally orby intrajejunal infusion (100 cm from the nose) to healthy subjects. 2. The ratio between the amount of radioactivity per mg PEG of intestinal aspirates and that of the test solution demonstrated that 90% of the given label is absorbed in theproximal part of the small intestine. 3. The maximum amount of label recovered in 3000 ml plasma corresponded to 3% of the given dose. 4. The cumulative excretion of label in urine and faeces during 6 days amounted to 65% and 5%, respectively. 5. A 50% yield of radioactivity in urine after an instillation of [3H]atropine into the jejunum 200 cm from the nose indicated that a substantial absorption occurs distal to this level. 6. The cumulative excretion of radioactivity in urine and faeces during 6 days after an intravenous injection of 1 mg [3H]atropine to one subject amounted to 66% and 1·5%, respectively. 7. Electrophoretic and chromatographic analyses of small intestinal aspirates showed no consistent evidence of a metabolic change of the drug.