title: Use of omeprazole in Zollinger-Ellison syndrome: a prospective nine-year study of efficacy and safety.
abstract: H+, K(+)-ATPase inhibitors such as omeprazole are the antisecretory agents of choice for the management of gastric acid hypersecretory states, including the Zollinger-Ellison syndrome. However, long-term follow-up data on the overall efficacy and safety of these agents in large numbers of patients are lacking. In the current study we examined the long-term efficacy and safety of omeprazole in 116 patients with Zollinger-Ellison syndrome treated with oral omeprazole at a single centre for up to 114 months (mean +/- S.E.M. = 38 +/- 3 months). The initial omeprazole maintenance dose was established according to the acute upward dose titration method in 89/116 patients (77%). Gastric acid output was effectively controlled using 60 mg of omeprazole once daily in 41/89 patients (46%) and 22/89 patients (25%) required twice daily omeprazole therapy. The mean ranitidine equivalent dose for patients who required 60 mg omeprazole once daily (2.5 +/- 0.2 g/day) was significantly lower than the mean ranitidine equivalent dose for patients who required more than 60 mg omeprazole once daily (4.3 +/- 0.3 g/day). Long-term omeprazole maintenance therapy was discontinued in 36/116 patients (31%) but in no cases was discontinuation due either to drug-induced side-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 the pre-omeprazole basal acid output (r = 0.41, P < 0.001) and ranitidine equivalent dose requirements (r = 0.49, P < 0.001). We conclude that omeprazole effectively and safely controls gastric acid hypersecretion in all patients with Zollinger-Ellison syndrome for up to nine years without evidence by tachyphylaxis.
authors.affiliation: Digestive Diseases Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892.
authors.forename: D C
authors.initials: DC
authors.lastname: Metz
authors.forename: D B
authors.initials: DB
authors.lastname: Strader
authors.forename: M
authors.initials: M
authors.lastname: Orbuch
authors.forename: P D
authors.initials: PD
authors.lastname: Koviack
authors.forename: K M
authors.initials: KM
authors.lastname: Feigenbaum
authors.forename: R T
authors.initials: RT
authors.lastname: Jensen
mesh_terms: D000284:Administration, Oral; D000293:Adolescent; D000328:Adult; D000368:Aged; D004305:Dose-Response Relationship, Drug; D005260:Female; D005500:Follow-Up Studies; D005744:Gastric Acid / Q000378:metabolism*; D005755:Gastrins / Q000097:blood; D006801:Humans; D008297:Male; D008875:Middle Aged; D009853:Omeprazole / Q000008:administration & dosage / Q000009:adverse effects / Q000494:pharmacology / Q000627:therapeutic use*; D011446:Prospective Studies; D011899:Ranitidine / Q000008:administration & dosage / Q000627:therapeutic use; D015043:Zollinger-Ellison Syndrome / Q000188:drug therapy*
chemical_list: D005755:Gastrins; D011899:Ranitidine; D009853:Omeprazole