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

After oral and intravenous administration of [14C]clarithromycin to rats, c. 60-70% of the radioactivity in the gastric tissue was found to be distributed in the mucosal layer. Co-administration of lansoprazole and amoxicillin had no apparent effect on this distribution pattern of [14C]clarithromycin. The amount of unchanged [14C]clarithromycin in gastric contents increased with co-administration of lansoprazole and amoxicillin. Microautoradiograms of the gastric mucosa showed that [14C]clarithromycin was highly distributed in the mucous layer and in surface epithelial cells following oral administration. Homogeneous distribution of radioactivity was evident in the fundic gland. With iv administration, [14C]clarithromycin seemed to be secreted by both secreting cells in the gland base and surface epithelial cells.