Abstract

Fifteen patients with peptic ulcer underwent 24 hour studies of gastric contents: before and on completing six weeks' treatment with oral ranitidine 150 mg bd, twice on maintenance treatment for nine to 12 months and one month after stopping the drug. For comparison, 11 patients underwent identical 24 hour studies three to 38 months after truncal vagotomy for duodenal ulcer. During treatment with ranitidine median 24 hour intragastric pH, nitrate concentration, and counts of total and nitrate reducing bacteria increased significantly regardless of dietary nitrate content; there was no significant increase in the median day time concentration of N-nitroso compounds. Despite these changes, an acid tide at some point in each 24 hour study period prevented persistent bacterial colonisation of the stomach. There were no significant differences between the biochemical and microbiological changes recorded during one year of treatment with ranitidine, and the observations on patients after truncal vagotomy. One month after stopping one year's treatment with ranitidine all variables examined returned to pretreatment levels. Treatment with ranitidine or vagotomy was associated with significant positive correlations among pH, nitrate concentration and bacterial counts. Correlations between pH and N-nitroso compound concentration and between concentrations of nitrite and N-nitroso compounds were not significant.