USE OF OMEPRAZOLE IN ZOLLINGER-ELLISON SYNDROME - A PROSPECTIVE 9-YEAR STUDY OF EFFICACY AND SAFETY

H+, K+-ATPase inhibitors such as omeprazole are the antisecretory agen ts of choice for the management of gastric acid hypersecretory states, including the Zollinger-Ellison syndrome. However, long-term follow-u p data on the overall efficacy and safety of these agents in large num bers of patients are lacking. In the current study we examined the lon g-term efficacy and safety of omeprazole in 116 patients with Zollinge r-Ellison syndrome treated with oral omeprazole at a single centre for up to 114 months (mean +/- S.E.M. = 38 +/- 3 months). The initial ome prazole maintenance dose was established according to the acute upward dose titration method in 89/116 patients (77%). Gastric acid output w as effectively controlled using 60 mg of omeprazole once daily in 41/8 9 patients (46%) and 22/89 patients (25%) required twice daily omepraz ole therapy. The mean ranitidine equivalent dose for patients who requ ired 60 mg omeprazole once daily (2.5 +/- 0.2 g/day) was significantly lower than the mean ranitidine equivalent dose for patients who requi red more than 60 mg omeprazole once daily (4.3 +/- 0.3 g/day). Long-te rm omeprazole maintenance therapy was discontinued in 36/116 patients (31%) but in no cases was discontinuation due either to drug-induced s ide-effects or uncontrolled gastric acid output. Fasting serum gastrin levels were significantly elevated above pre-treatment levels at only one time point during follow-up and were likely due to tumour growth rather than a drug effect. The final long-term omeprazole maintenance doses were lower than the initial doses but correlated closely with th e pre-omeprazole basal acid output (r = 0.41, P < 0.001) and ranitidin e equivalent dose requirements (r = 0.49, P < 0.001). We conclude that omeprazole effectively and safely controls gastric acid hypersecretio n in all patients with Zollinger-Ellison syndrome for up to nine years without evidence by tachyphylaxis.