A pharmacodynamic study of two omeprazole regimens suitable for long-term treatment of duodenal ulcer

The experience with long-term treatment of peptic ulcer with omeprazole is still scant, but the possibility cannot be excluded that its better pharmacodynamic effect on gastric acidity also has a positive result in the relapse rate. Moreover, this drug acts via a mechanism other than receptorial binding, and therefore its efficacy should not dissipate with time. This study was carried out to assess the pharmacodynamic properties and the possible changes with time of two dose regimens of omeprazole that could be suitable for long-term treatment in duodenal ulcer.

Twenty patients with endoscopically proven duodenal ulcer were studied by means of 24-h gastric pH-metry both in basal conditions and on the 5th day of acute treatment with 40 mg omeprazole in the morning. All the ulcers healed after 4 weeks, and thereafter 10 patients were randomized to receive orally 20 mg omeprazole daily at 0800 h in single-blind fashion (group A) and 10 to receive 20 mg omeprazole every other day (group B) for up to 6 months. At the end of the 1st, 3rd, and 6th month of these maintenance treatments 24-h gastric pH-metry was repeated to assess the antisecretory effect of each regimen over time. In group-B patients the test was performed on 2 consecutive days (without and with medication) at each time interval. The fasting gastrin values were also determined. The patients underwent esophagogastroduodenoscopy every 2 months.

Three patients in group B were lost to follow-up for various reasons, and only seven remained eligible for final analysis. The two long-term regimens of omeprazole were able to increase significantly pH values (p < 0.02-0.001) and the times spent at and above pH 3.0 (p < 0.001) over 24 h compared with basal conditions. In group A the 24-h pH value obtained in the 6th month was higher (p < 0.02) than that in the 3rd month of maintenance treatment. In group B the pharmacologic effect tended to decrease on the day without medication compared with the day with medication, but the difference between them was significantly (p < 0.05) only at the 6-month interval. There was no significant difference between the gastrin levels of the two groups in the long-term treatment. No ulcer relapse was detected at any long-term endoscopic control in the two groups of patients.

The two omeprazole regimens we tested are effective in reducing gastric acidity, and their pharmacodynamic action does not decrease with time. They are therefore suitable for maintenance treatment in acid-related disorders.