Localization of [14C]amoxicillin in rat gastric tissue when administered with lansoprazole and clarithromycin.

The gastric mucosal distribution of [14C]amoxicillin when administered to rats with or without lansoprazole and clarithromycin was investigated. After oral administration, the amount found in the gastric mucosa was higher than after iv administration. Co-administration of lansoprazole and clarithromycin had no apparent effect on the distribution pattern of [14C]amoxicillin within the deeper stomach layers. About 50-60% of the radioactivity in the gastric tissue was present in the mucosal layer, irrespective of the route of administration. Microautoradiograms of the gastric mucosa indicated that [14C]amoxicillin was distributed in both the mucous layer and surface epithelial cells following oral administration. [14C]amoxicillin was secreted mainly by surface epithelial cells after iv administration, although only in small quantities.