Comparison of once-daily intravenous and oral omeprazole on pentagastrin-stimulated acid secretion in duodenal ulcer patients.

The effect of 5 days of once-daily dosing with 20 mg p.o. and 40 mg i.v. omeprazole on pentagastrin-stimulated acid secretion was studied in 8 patients with duodenal ulcer. In addition they also received a 10-mg i.v. dose on day 6 during the oral treatment period. The antisecretory effect was measured 6-7 h after dose at a time point when maximal inhibition during the dosing interval is anticipated. The median percent inhibition of peak acid output (PAO) markedly increased from 43% on day 1 to 100% on day 5 during treatment with 20 mg p.o. The first 40-mg i.v. dose produced a median inhibition of 98% of PAO already on day 1. After 5 days of dosing, the inhibition had increased to 100%. On the other hand, a 10-mg i.v. dose could essentially maintain the degree of PAO reduction reached after 5 days of oral treatment. Plasma omeprazole concentrations increased during repeated dosing both with 20 mg p.o. and 40 mg i.v.