A PHARMACODYNAMIC STUDY OF 2 OMEPRAZOLE REGIMENS SUITABLE FOR LONG-TERM TREATMENT OF DUODENAL-ULCER

Background: The experience with long-term treatment of peptic ulcer wi th omeprazole is still scant. but the possibility cannot be excluded t hat its better pharmacodynamic effect on gastric acidity also has a po sitive result in the relapse rate. Moreover, this drug acts via a mech anism other than receptorial binding, and therefore its efficacy shoul d not dissipate with time. This study was carried out to assess the ph armacodynamic properties and the possible changes with time of two dos e regimens of omeprazole that could be suitable for long-term treatmen t in duodenal ulcer. Methods: Twenty patients with endoscopically prov en 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 o meprazole in the morning. All the ulcers healed after 4 weeks, and the reafter 10 patients were randomized to receive orally 20 mg omeprazole daily at 0800 h in single-blind fashion (group A) and 10 to receive 2 0 mg omeprazole every other day (group B) for up to 6 months. At the e nd of the 1st, 3rd, and 6th month of these maintenance treatments 24-h gastric pH-metry was repeated to assess the antisecretory effect of e ach 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 underwe nt esophagogastroduodenoscopy every 2 months. Results: Three patients in group B were lost to follow-up for various reasons, and only seven remained elegible for final analysis. The two long-term regimens of om eprazole 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 compar ed 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 mainten ance 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 significant (p < 0.05) only at the 6-month term treatment. There was no significant difference between t he gastrin levels of the two groups in the long-term treatment. No ulc er relapse was detected at any long-term endoscopic control in the two groups of patients. Conclusions: The two omeprazole regimens we teste d are effective in reducing gastric acidity, and their pharmacodynamic action does not decrease with time. They are therefore suitable for m aintenance treatment in acid-related disorders.