Intragastric acidity under 28-day omeprazole treatment.

The aim of our study was to investigate both the effect of 28-day treatment with omeprazole (30 mg orally once daily) and of repeated investigations on 24 h intragastric H+ activity. In double-blind randomized order, 10 healthy subjects received omeprazole and 5 placebo. 24 h acidity was determined before, during and after, treatment on days -8, -4, -1, 14 and 28, 32, 36, 42 and 70. A 90% reduction in the 24 h acid concentration was found after 14 and 28 days of treatment. Nocturnal H+ activity was decreased by 85%. No hyperacidity was observed after withdrawal of the drug. Control levels before, (between days -8 and -1) and after, therapy (between days 36 and 70), however, showed a significant increase in 24 h intragastric H+-activity. Summarizing, omeprazole 30 mg mane inhibits gastric acidity markedly both day and night. Repeated investigations at short intervals lead to a significant increase in intragastric acid concentration.