1. After oral administration of [14C]carbenoxolone (100 mg, 5 μCi) to patients with radiologically-proven gastric ulcers the radioactivity was excreted mostly in the faeces (70–80%) with lesser amounts in the expired CO2 (12–20%) and only traces in the urine (0·2–1%). This is in marked contrast with the metabolism and pattern of excretion of this drug in the rat.
2. Most of the radioactivity excreted in the faeces of patients was present as carbenoxolone, which was probably formed by bacterial hydrolysis of the biliary-excreted conjugate of carbenoxolone.
3. It is concluded that in man orally administered carbenoxolone is absorbed mostly unchanged, in contrast with the rat in which the orally administered drug is substantially hydrolysed to β-glycyrrhetic acid and succinic acid before absorption.