For the treatment of duodenal and gastric ulcer and reflux oesophagitis, especially erosive oesophagitis, omeprazole has an advantage over histamine H2-receptor antagonists because it heals significantly more patients significantly faster. Adverse effects have been observed during short term treatment with the same frequency as during treatment with H2-antagonists.
Also, maintenance treatment with omeprazole of reflux oesophagitis is significantly superior to H2-antagonist therapy. During long term treatment for up to 8 years no further drug-related adverse effects have been observed. Moderate hypergastrinaemia occurs in some patients, especially if an omeprazole dosage of 40 mg/day is needed.
A slight increase of the agyrophil (endocrine) cell volume density and an extension of micronodular hyperplasia in the oxyntic mucosa after several years of omeprazole treatment seem to be related to the severity of the corpus gastritis and not to drug-induced hypergastrinaemia, because similar changes have been observed in equal frequency in patients not receiving anti-secretory drugs.
Theoretical arguments against long term treatment with potent acid-suppressing drugs, such as the possible consequences of gastric bacterial overgrowth or hypergastrinaemia, are not supported by clinical observations and epidemiological data and are, therefore, speculative.