Carbenoxolone interactions in man--preliminary report

Carbenoxolone is a potent ulcer-healing drug which is extensively bound to plasma proteins and therefore has the potential for displacement interaction. However, carbenoxolone has been shown to be bound to human serum albumin in vitro at a different class of binding site to many other drugs and does not potentiate the pharmacological activity of warfarin, tolbutamide, chlorpropamide or phenytoin in the rat. In the present study four volunteers each received a single 100 mg dose of Biogastrone and the plasma half-life of carbenoxolone was determined. The procedure was repeated with a concurrent dose of either warfarin 10 mg, tolbutamide 500 mg, chlorpropamide 250 mg or phenytoin 100 mg. Chlorpropamide appeared to delay the absorption of carbenoxolone but no effects were observed with the other drugs. The study with concomitant chlorpropamide treatment was repeated with 6 gastric ulcer patients on an established Biogastrone regimen. In these patients the delayed absorption of carbenoxolone was confirmed although no changes in the glucose-lowering activity of chlorpropamide were evident. Further investigations into this findings are in progress.