Proton pump inhibitors (PPIs) are widely used to treat hyperacid secretion and
stomach ulcers. The study investigated the anti-secretory and anti-
ulcer effects of
esomeprazole, the S-isomer of
omeprazole on
dimaprit,
histamine and dibutyryl
adenosine 3, 5 cyclic monophosphate (
dbcAMP)-evoked gastric acid secretion, acidified
ethanol (AE) and
indomethacin (INDO)-induced haemorrhagic lesions and on
prostaglandin E2 (
PGE2) level in the rat in vivo and rabbit in vitro preparations. The effect of
omeprazole was also investigated for comparison.
Dimaprit-induced
acid secretion was significantly (P < 0.05) inhibited by both PPIs in a dose-dependent manner. In the isolated rabbit gastric glands, both PPIs elicited marked reductions in
histamine- and
dbcAMP-evoked
acid secretion with similar potency. The lesions induced by either AE or INDO were significantly (P < 0.05) reduced in the presence of either
esomeprazole or
omeprazole compared to control values. Increasing doses of
esomeprazole before AE treatment resulted in a marked degree of cytoprotection and an elevation in the concentration of bound
PGE2 in the stomach tissue homogenate. The results show that
esomeprazole and
omeprazole were equally effective against gastric haemorrhagic lesions induced by either AE or INDO and in inhibiting
dimaprit-,
dbcAMP- and
histamine-induced gastric acid secretion in the rat and rabbit stomach both in vivo and in vitro. The gastro-protective effect of
esomeprazole was found to be proportional to the bound
PGE2 levels in the glandular area of the stomach.