Use of omeprazole in patients with Zollinger-Ellison syndrome

Omeprazole, a substituted benzimidazole, has been shown to be a potent inhibitor of gastric acid secretion in patients with Zollinger-Ellison syndrome (ZES). We review our experience, as well as the published data on 210 patients with ZES who have required omeprazole for control of gastric acid hypersecretion over the past seven years. The dose of omeprazole required in individual patients ranged from 10 to 180 mg/24 hr with 20-60% requiring a split dosage regimen. Omeprazole was effective in approximately 99% of the patients over a period ranging from 0.5 to 54 months. Twenty-four percent of patients required an increase in omeprazole dose, while 26% required a decrease in dose. Adverse effects attributable to omeprazole were reported in 2% of patients, and in all cases, they were mild (ie, rash, constipation, headache). There was no effect of omeprazole on serum gastrin concentration or on gastric endocrine cells in three studies. Although one patient with multiple endocrine neoplasia, type-I syndrome (MEN-I) in this series developed a gastric carcinoid while taking omeprazole, evidence is presented that suggests the presence of MEN-I per se may be important in determining the development of gastric carcinoid in patients with ZES. It is concluded that omeprazole is safe and effective in patients with ZES, and in these patients, it is the drug of choice for the management of gastric acid hypersecretion. However, yearly assessment is indicated to clearly evaluate the long-term risk of gastric carcinoid as well as therapy directed at the gastrinoma itself.     

Oral pantoprazole for acid suppression in the treatment of patients with Zollinger-Ellison syndrome.

BACKGROUND: The management of patients with gastric acid hypersecretion due to gastrinoma, usually recognized as Zollinger-Ellison syndrome (ZES), was radically changed 10 years ago by the use of proton pump inhibitors. Surgical treatment now concentrates on tumour excision, and in the majority of patients, gastrectomy is no longer required to prevent complications of acid hypersecretion that can be managed pharmacologically. AIMS: To verify the ability of pantoprazole to control gastric acid hypersecretion and the clinical effects of acid hypersecretion in seven patients with documented ZES. METHODS: Pantoprazole was administered at an initial dose of 80 mg daily for seven days before basal acid output (BAO) was measured at 08:00, ie, 1 h before the next dose of pantoprazole was normally ingested. A lower (40 mg) or higher (120 mg or more) dose of pantoprazole was then used to keep the BAO in the therapeutic range (between 0.1 and 10 mmol/h) and to control clinical symptoms such as acid-related pain or diarrhea. RESULTS: BAO and clinical symptoms were controlled with pantoprazole 40 mg daily in one patient, 80 mg daily in two patients, 120 mg daily in three patients and 160 mg daily in one patient. CONCLUSIONS: Pantoprazole was able to control acid hypersecretion in ZES patients when administered in doses between 40 and 160 mg daily. An initial dose of 120 mg given before further titration of the drug regimen appears to be a reasonable therapeutic strategy.     

Omeprazole: effective, convenient therapy for Zollinger-Ellison syndrome

The acute and long-term effects of omeprazole on gastric acid secretion were examined in 11 patients with Zollinger-Ellison syndrome. Basal gastric acid secretion was inhibited by 50% 3 h after a single 60-mg dose of omeprazole and 78% 4 h after administration of omeprazole. Patients were treated with a single daily dose of omeprazole, and the dose requirement was defined as the lowest dose of omeprazole that would reduce gastric acid secretion to less than 10 mEq/h during the last hour before the next dose. The mean daily dose requirement was 70 mg (range 20-160 mg). Ten of the 11 patients were given omeprazole once a day and 1 patient required omeprazole every 12 h. When omeprazole was discontinued after several months of therapy, mean basal gastric acid secretion was inhibited by greater than 50% 48 h after administration of omeprazole. Omeprazole continued to inhibit gastric acid secretion during 1-9 mo of therapy and patients remained free of toxicity or side effects related to omeprazole. Omeprazole is a highly effective inhibitor of gastric acid secretion in patients with Zollinger-Ellison syndrome. Because of its potency and long duration of action, omeprazole offers an advance in convenient medical therapy for Zollinger-Ellison syndrome compared with the histamine H2-receptor antagonists.     

Maintenance oral pantoprazole therapy is effective for patients with Zollinger-Ellison syndrome and idiopathic hypersecretion

OBJECTIVE: Maintenance proton pump inhibitor (PPI) therapy is effective for gastric acid hypersecretory states, although data with pantoprazole are limited. The aim of this study was to evaluate the safety and efficacy of long term p.o. pantoprazole in individuals with hypersecretion. METHODS: All subjects had Zollinger-Ellison syndrome or idiopathic hypersecretion. Baseline acid output was measured in the presence of prior maintenance antisecretory therapy before pantoprazole exposure. The starting dose was 40 mg b.i.d. in most cases, and the dose was adjusted to document control within the first 2 wk of therapy. The maximal allowable dose was 240 mg daily. Acid output was measured on day 28 and then quarterly from month 3. The primary efficacy endpoint was documented control of acid secretion at 6 months, i.e., acid output in the last 1 h before the next dose of therapy of <10 mEq/h (<5 mEq/h in subjects with prior acid-reducing surgery). RESULTS: A total of 26 subjects had Zollinger-Ellison syndrome (six with multiple endocrine neoplasia syndrome type 1) and nine had idiopathic hypersecretion. Pre-enrollment therapy included omeprazole in 27 subjects and lansoprazole in eight, and 82.4% of subjects were controlled on their prior regimens. With upward dose titration, acid output was controlled in all subjects by day 10 and in all but two (6%) at the 6-month time point. Median acid secretion on therapy at 6 months was <2 mEq/h (mean 2.2 mEq/h; range 0-10.5 mEq/h) at a dose of 40 mg b.i.d. for 24 subjects, 80 mg b.i.d. for seven subjects, and 120 mg b.i.d. for two subjects. During the course of the study, five subjects required doses of 240 mg daily. Pantoprazole was generally well tolerated. No cases of anterior optic ischemic neuropathy occurred. Five subjects died during follow-up, all because of events unrelated to the study drug. CONCLUSIONS: Maintenance p.o. pantoprazole therapy at a dose of 80-240 mg/day in divided doses was both effective and generally well tolerated for patients with Zollinger-Ellison syndrome and idiopathic hypersecretion.     

Replacement of oral proton pump inhibitors with intravenous pantoprazole to effectively control gastric acid hypersecretion in patients with Zollinger-Ellison syndrome

OBJECTIVES: In patients with Zollinger-Ellison syndrome (ZES) or other conditions requiring oral doses of proton pump inhibitors, it frequently becomes necessary to use parenterally administered gastric acid inhibitors. However, i.v. histamine-2 receptor antagonists are not effective at usual doses and lose their effectiveness because of tachyphlaxis. With the approval in the United States of i.v. pantoprazole, a substituted benzimidazole available in i.v. formulation, it will become possible to acutely manage gastric acid secretion in the acute care setting of a hospital. This study was developed to monitor the safety and establish the efficacy of i.v. pantoprazole as an alternative to oral proton pump inhibitors for the control of gastric acid hypersecretion in patients with ZES. METHODS: The efficacy of replacing oral PPI therapy with i.v. pantoprazole was evaluated in 14 ZES patients. After study enrollment, patients taking their current doses of oral PPI (omeprazole or lansoprazole) were switched to pantoprazole i.v. for 6 days during an 8-day inpatient period in the clinical research center. Effective control was defined as an acid output (AO) of < 10 mEq/h (< 5 mEq/h in patients with prior gastric acid-reducing surgery). RESULTS: The mean age of the 14 patients enrolled in the study was 52.4 yr (range = 38-67). Mean basal AO was 0.55 +/- 0.32 mEq/h and mean fasting gastrin was 1089 pg/ml (range = 36-3720). Four patients were also diagnosed with the multiple endocrine neoplasia type I syndrome, nine were male, and two had previously undergone acid-reducing surgery. Before study enrollment, gastric acid hypersecretion was controlled in nine of 14 patients with omeprazole (20-200 mg daily) and five of 14 with lansoprazole (30-210 mg daily). In the oral phase of the study all patients had adequate control of gastric acid secretion, with a mean AO of 0.55 +/- 0.32 mEq/h (mean +/- SEM). Thereafter, 80 mg of i.v. pantoprazole was administered b.i.d. for 7 days by a brief (15 min) infusion and the dose was titrated upward to a predetermined maximum of 240 mg/24 h to control AO. A dose of 80 mg b.i.d. of i.v. pantoprazole controlled AO in 13 of 14 of the patients (93%) for the duration of the study (p > 0.05 compared to baseline values for all timepoints). One sporadic ZES patient (oral control value = 0.65 mEq/h on 100 mg of omeprazole b.i.d. p.o.) was not controlled with 80 mg of i.v. pantoprazole b.i.d. and dosage was titrated upward to 120 mg b.i.d. after day 2. CONCLUSIONS: There were no serious adverse events observed. Intravenous pantoprazole provides gastric acid secretory control that is equivalent to the acid suppression observed with oral proton pump inhibitors. Most ZES patients (93%) maintained effective control of AO previously established with oral PPIs when switched to 80 mg of i.v. pantoprazole b.i.d.; however, for difficult-to-control patients, doses > 80 mg b.i.d. may be required.     

Effects of esomeprazole on acid output in patients with Zollinger-Ellison syndrome or idiopathic gastric acid hypersecretion

OBJECTIVES: To evaluate the efficacy and safety of oral esomeprazole in the control of gastric acid hypersecretion in patients with hypersecretory states. METHODS: In this 12-month, open-label, multicenter study, acid output (AO) was evaluated at baseline, day 10, and months 3, 6, and 12. The starting dose of esomeprazole was 40 mg or 80 mg twice daily. On day 10, patients with controlled AO were maintained on the same dose, while those with uncontrolled AO had their doses increased (maximum dose 240 mg/day) until control was attained. Esophagogastroduodenoscopy (EGD) was performed at baseline and at 6 and 12 months. Safety and tolerability were assessed throughout the study by EGD, gastric analysis, and adverse events. RESULTS: Twenty-one patients (19 with Zollinger-Ellison syndrome [ZES], 2 with idiopathic gastric acid hypersecretion [IGH]) completed the study. Of the 20 patients with controlled AO at day 10, 18 (90%) had sustained AO control for the rest of the study. At 12 months, AO was controlled in 14 of 16 patients receiving esomeprazole 40 mg twice daily, in all 4 patients receiving esomeprazole 80 mg twice daily, and in the 1 patient receiving esomeprazole 80 mg 3 times daily. At 6 and 12 months, no patient had endoscopic evidence of mucosal disease. Esomeprazole was well tolerated; 1 patient had a serious adverse event (hypomagnesemia) attributed to treatment that resolved with magnesium supplementation during continued treatment. CONCLUSION: Esomeprazole in appropriately titrated doses controls AO over 12 months in patients with hypersecretory states and is well tolerated.     

Parenteral control of gastric acid hypersecretion in patients with Zollinger-Ellison syndrome

Parenteral control of gastric acid hypersecretion in patients with Zollinger-Ellison syndrome is increasingly required; however, existing methods of determining the required dose are cumbersome and not applicable in all centers. A previous study suggested that the required parenteral dose of histamine H₂-receptor antagonists correlated with the previous oral dose. In the present study, in 31 patients with Zollinger-Ellison syndrome we evaluated the hypothesis that an effective parenteral histamine H₂-receptor antagonist dose could be predicted from the previous oral dose. Twenty-three patients were taking oral ranitidine (mean 1.3 g/day), six patients famotidine (152 mg/day), and two patients cimetidine (1.8 g/day). Each patient was treated with a continuous intravenous infusion of the equivalent dose of ranitidine (mean dose 1 mg/kg/hr with 35% requiring 0.5 mg/kg/hr, 49% 1 mg/kg/hr, 3% 1.5 mg/kg/hr, 10% 2 mg/kg/hr, and 3% 2.5 mg/kg/hr. This dose of ranitidine acutely controlled acid secretion (<10 meq/hr) in all patients. To evaluate long-term efficacy and safety, 20 patients were maintained on this dose through the peri-and postoperative periods. Mean duration was 7.1 days with 25% treated 3–5 days, 40% 6–8 days, 30% 8–10 days, and 5%>10 days. The predicted dose continued to control acid secretion in 95% of patients with one patient requiring one dose adjustment. No biochemical, clinical, or hematological toxicity was seen, although ranitidine was stopped in one patient because of skin rash. These results demonstrate that the parenteral dose of ranitidine required to control acid secretion in patients with Zollinger-Ellison syndrome can be predicted from the oral dose. This predicted dose will be acutely effective in all patients in reducing acid secretion to <10 meq/hr, the established level of control, will remain effective in 95% of patients for up to 11 days, and is safe. By utilizing the oral dose to predict the intravenous dose, repeated dose titrations will be avoided and thus this method should be generally useful in all settings.     

Effect of 7-day therapy with different doses of the proton pump inhibitor lansoprazole on the intragastric pH in healthy human subjects.

BACKGROUND: Systematic, randomized, and controlled studies on the effect of low to high doses of the proton pump inhibitor lansoprazole on intragastric acidity and plasma gastrin levels have not previously been performed. METHODS: We investigated the effect of 7-day therapy with different doses of lansoprazole (15 mg once or twice daily, 30 mg once or twice daily, and 15 mg three times daily) on intragastric acidity and meal-stimulated daytime plasma gastrin levels in 12 healthy Helicobacter pylori-negative human subjects in a randomized, double-blind, placebo-controlled, 6-way crossover study. On days 1, 2, and 7 of the study 24-h intragastric pH-metry and 12-h integrated daytime plasma gastrin determinations were done. RESULTS: Lansoprazole in a dose regimen of 1 x 30 mg/day, 3 x 15 mg/daily, and 2 x 30 mg/day significantly (P < 0.05) increased the intragastric 24-h median pH on days 1, 2, and 7 of therapy as compared with placebo. Lansoprazole in doses of 1 x 15 mg/day and 2 x 15 mg/day significantly increased the intragastric 24-h median pH on days 2 and 7 but not on day 1 of therapy. Doses of 3 x 15 mg and 2 x 30 mg lansoprazole daily significantly increased the intragastric 24-h median pH on days 2 and 7 of treatment as compared with 1 x 30 mg lansoprazole daily. Except for 1 x 15 mg lansoprazole on day 1 of therapy, all given dose regimens of lansoprazole (15-60 mg/day) significantly (P < 0.05) stimulated the 12-h integrated meal-stimulated daytime plasma gastrin response (pM x min) on days 1, 2, and 7 of therapy as compared with placebo. CONCLUSION: A dose of 1 x 30 mg/day is nearly as potent as higher dose regimens of lansoprazole. Thus it most likely is the optimum dose for therapy of gastric and duodenal peptic lesions. A dose of 1 x 15 mg lansoprazole daily is a potent inhibitor of gastric acid output and could be a therapeutic dose for prevention of peptic lesions (that is, reflux oesophagitis or ulcers).     

Intravenous pantoprazole rapidly controls gastric acid hypersecretion in patients with Zollinger-Ellison syndrome

BACKGROUND & AIMS: Parenteral control of gastric acid hypersecretion in conditions such as Zollinger-Ellison syndrome (ZES) or idiopathic gastric acid hypersecretion is necessary perioperatively or when oral medications cannot be taken for other reasons (e.g., during chemotherapy, acute upper gastrointestinal bleeding, or in intensive care unit settings). METHODS: We evaluated the efficacy and safety of 15-minute infusions of the proton pump inhibitor pantoprazole (80-120 mg every 8-12 hours) in controlling acid output for up to 7 days. Effective control was defined as acid output >10 milliequivalents per hour (mEq/h) (<5 mEq/h in patients with prior acid-reducing surgery) for 24 hours. RESULTS: The 21 patients enrolled had a mean age of 51.9 years (range, 29-75) and a mean disease duration of 8.1 years (range, <0.5-21); 13 were male, 7 had multiple endocrine neoplasia syndrome type I, 4 had undergone acid-reducing surgery, 2 had received chemotherapy, and 13 had undergone gastrinoma resections without cure. Basal acid output (mean +/- SD) was 40.2 +/- 27.9 mEq/h (range, 11.2-117.9). In all patients, acid output was controlled within the first hour (mean onset of effective control, 41 minutes) after an initial 80-mg intravenous pantoprazole dose. Pantoprazole, 80 mg every 12 hours, was effective in 17 of 21 patients (81%) for up to 7 days. Four patients required upward dose titration, 2 required 120 mg pantoprazole every 12 hours, and 2 required 80 mg every 8 hours. At study end, acid output remained controlled for 6 hours beyond the next expected dose in 71% of patients (n = 15); mean acid output increased to 4.0 mEq/h (range, 0-9.7). No serious or unexpected adverse events were observed. CONCLUSIONS: Intravenous pantoprazole, 160-240 mg/day administered in divided doses by 15-minute infusion, rapidly and effectively controlled acid output within 1 hour and maintained control for up to 7 days in all ZES patients.     

Gastric H+, K+-ATPase as a therapeutic target in peptic ulcer disease

The presence of unbuffered acid appears to be an essential contributory factor in the pathogenesis of peptic ulcer disease. Treatment has concentrated therefore on the reduction of acidity, and the last decade has seen the widespread and effective use of H₂ antagonists. They are, at low doses, more successful in improving the natural history of duodenal ulcer disease than of gastric or esophageal ulceration. The H₂ receptor plays a central role in activation of parietal cell acid secretion, and antagonists at this receptor block most (but not all) of the acid secretion due to even gastrinergic or muscarinic (vagal) stimulation. In hypergastrinemic states such as Zollinger-Ellison syndrome, or where acid secretion has to be inhibited by more than 20% over a 24-hr period, such as for treatment of esophagitis, NSAID damage, or gastric ulcers, the dose and frequency of administration of the currently available antagonists must be increased to achieve reliable therapy. This has led to a search for an alternative target for acid inhibitory drugs, such as the gastric acid pump, the H⁺,K⁺-ATPase. This article focuses on the function of this ATPase and suggests that inhibition of this pump will provide a more efficacious means of reduction of acid secretion by the stomach, hence improving and simplifying therapy of acid related diseases.This work was supported in part by grants from NIH and the USVA.     

Idiopathic gastric acid hypersecretion

Many patients with acid-peptic disease have idiopathic gastric acid hypersecretion defined as a basal acid output >10.0 meq/hr; however, a significant proportion have basal acid outputs >15.0 meq/hr, which is within the range found in Zollinger-Ellison syndrome. Although idiopathic gastric acid hypersecretion is more common than Zollinger-Ellison syndrome, it is important that these two disorders be differentiated because of differences in treatment and natural history. In the present study, we compared 124 patients with idiopathic gastric acid hypersecretion and 137 patients with Zollinger-Ellison syndrome. There were no significant differences with regard to age at diagnosis, history of upper gastrointestinal hemorrhage, nausea, vomiting, and family history of duodenal ulcer and other acid-peptic disease. However, significant differences were observed between patients with idiopathic gastric acid hypersecretion and patients with Zollinger-Ellison syndrome with regard to percentage of males: 77% compared to 64% (P=0.008), mean serum gastrin: 60 pg/ml compared to 3679 pg/ml (normal <100 pg/ml) (P<0.001), mean basal acid output: 15.4 meq/hr compared to 47.0 meq/hr (P<0.001), mean age at onset of symptoms: 33 years compared to 41 years (P<0.001), mean duration of symptoms before diagnosis: 11 years compared to five years (P<0.001), percentage with abdominal pain: 67% compared to 82% (P=0.00004), percentage with diarrhea: 12% compared to 75% (P<0.000001), percentage with pyrosis: 58% compared to 40% (P=0.003), percentage with duodenal ulcer: 53% compared to 74% (P<0.000001), and percentage with esophagitis: 31% compared to 42% (P=0.0004). The differences in clinical features could be attributed to difference in mean basal acid output, and/or differences in levels of basal acid output used for diagnosis of idiopathic gastric acid hypersecretion (basal acid output >10.0 meq/hr) and Zollinger-Ellison syndrome (basal acid output >15.0 meq/hr). When 45 patients with idiopathic gastric acid hypersecretion and 39 patients with Zollinger-Ellison syndrome with basal acid outputs 15.1–30.0 meq/hr were compared, the main significant differences were with regard to mean serum gastrin: 69 pg/ml compared to 655 pg/ml (P<0.001), percentage of male gender: 82% compared to 62% (P=0.03), and percentage with diarrhea: 16% compared to 64% (P=0.000005). These results indicate that in general patients with idiopathic gastric acid hypersecretion and patients with Zollinger-Ellison syndrome often have similar clinical features that can be difficult to distinguish. However, the increased frequency of diarrhea and female gender should lead to a strong suspicion of Zollinger-Ellison syndrome, which can be distinguished in almost every case by measurement of serum gastrin.     

Histopathology of the gastric oxyntic mucosa in two different patient groups during long-term treatment with omeprazole

OBJECTIVES: Hypochlorhydria, hypergastrinaemia, inflammation and Helicobacter pylori infection, dose and duration of omeprazole treatment may separately, or in combination, influence the proliferation of enterochromaffin-like (ECL) cells and parietal cell changes in gastric mucosa. To assess the effects of these variables comparisons were carried out in patients with the acid related Zollinger-Ellison syndrome (ZES) versus patients with progressive systemic sclerosis (PSS) and gastro-oesophageal reflux disease. METHODS: Twenty-five patients with PSS and 16 patients with ZES were included and received continuous omeprazole treatment for a mean of 7.5 and 9 years. The patients were investigated every 6-12 months with endoscopy, biopsies and histology, and plasma gastrin measurements. PSS patients were titrated by 24 h pH-metry to oesophageal pH>4, and all ZES patients were titrated to a basal acid output of zero H+. RESULTS: Changes towards diffuse and linear ECL cell hyperplasia were observed in 41% of the PSS patients. Micronodular hyperplasia and neoplasia were not seen. In the ZES patients changes towards linear and micronodular hyperplasia were observed in all patients. Two patients developed ECL cell carcinoids; one of these had MEN-1 syndrome. Also parietal cell changes were more pronounced in the ZES group than in the PSS group. CONCLUSIONS: In patients without intrinsic acid hypersecretion and hypergastrinaemia significant proliferation of ECL cells is not an issue irrespective of gastric mucosal inflammation, omeprazole dose, duration of treatment and acid inhibition. The level of gastrin secretion and high plasma gastrin appear to accelerate ECL cell proliferation and parietal cell changes possibly influenced by chronic gastritis and H. pylori infection.     

Ranitidine therapy in patients with idiopathic gastric acid hypersecretion

One hundred twenty-four patients with idiopathic gastric acid hypersecretion (basal acid output greater than 10.0 meq/hr) were prospectively evaluated and treated with ranitidine twice a day. Fifty-four patients (44%) required standard doses of ranitidine 300 mg/day for adequate treatment, and the other 70 patients (56%) required increased doses of ranitidine (mean 994 mg/day, range 600–3000 mg/day). Mean basal acid outputs for these two groups were 14.0 and 16.6 meq/hr, respectively, which were not significantly different. Nevertheless, there was a significant correlation between basal acid output and daily ranitidine dose required for therapy (r=0.18,P=0.05). The duration of ranitidine therapy consisted of: <1 year (N=46), 1 year (N=16), 2 years (N=19), 3 years (N=22), 4 years (N=15), 5 years (N=6). Only five patients required progressive increases in ranitidine during the time of treatment, which consisted of an average of 0.5 dose adjustments per year. No side effects occurred with any of these high doses of ranitidine. These results indicate that, as in Zollinger-Ellison syndrome, ranitidine is effective therapy for patients with idiopathic gastric acid hypersecretion; however, markedly increased doses as large as 3000 mg/day may be required.     

Currently used doses of omeprazole in Zollinger-Ellison syndrome are too high.

The efficacy of omeprazole increases during the first few days of administration, suggesting that long-term maintenance dose requirements in patients with Zollinger-Ellison syndrome may be lower than those initially established by upward titration. Long-term maintenance doses of omeprazole were prospectively reduced in 37 patients who had been taking omeprazole for 22 +/- 4 months. Successful reduction was defined as reduction to 20 mg once or twice daily with an absence of symptoms, endoscopy without evidence of active acid-peptic disease, and a gastric acid output of < 10 mEq/h. Sixty-eight percent of patients (25/37) were successfully reduced to 20 mg of omeprazole once (18/24) or twice daily (7/13). Ninety-five percent of patients (20/21) without multiple endocrine neoplasia type I, severe gastroesophageal reflux disease, or previous partial gastrectomy had safe reductions of doses. It is concluded that the currently used omeprazole maintenance doses in patients with Zollinger-Ellison syndrome are too high and advocated that the initial dose still be established by acute daily upward titration followed by gradual reduction once control of acid output has been achieved.     

Zollinger-Ellison phenotype in the absence of hypergastrinemia and islet-cell tumor

Patients with the Zollinger-Ellison syndrome are characterized by islet-cell tumors, striking gastric acid hypersecretion, and peptic ulcer disease. They often experience severe abdominal pain, diarrhea, and gastrointestinal bleeding with potentially life-threatening consequences. It is a rare syndrome caused by nonbeta cell islet-cell tumors (gastrinomas) located in or in proximity to the pancreas. These tumors freely secrete gastrin, a peptide hormone that serves as a powerful stimulant of gastric acid secretion. Exuberant secretion of gastrin from the gastrinomas produces severe gastric acid hypersecretion that often leads to impressive peptic ulcer disease and the constellation of symptoms listed above. We describe a patient presenting with clinical manifestations characteristic of the ZES with strikingly elevated gastric acid secretion, multiple ulcers in the first and second portions of the duodenum and diarrhea, but in absence of islet-cell tumor and/or hypergastrinemia.     

A nongastrin malignant ampullary tumor causing gastric acid and pepsin hypersecretion. A case report

We report a case of multiple duodenal ulcers with gastric hypersecretion due to a nongastrin secretagogue produced by a malignant tumor of the pancreas in a 78-year-old man. The case resembled a Zollinger-Ellison syndrome (ZES) with high acid output (basal acid output 27, sham meal-stimulated 37, maximum acid output 47 mEq/h), but with fasting gastrin 43 pg/ml, nonresponsive to secretin. As in ZES, pepsin output was comparatively low, and secretion was inhibitable by atropine (50% inhibited by 1 microM). The tumor removed at surgery contained less than 1 ng gastrin per gram, but was many times more potent than pentagastrin in stimulating acid from a lumen-perfused rat stomach. The tumor also contained cholecystokinin (CCK-8 and CCK-33), motilin, insulin, and somatostatin, which were also present in adjacent normal pancreas; in addition, the tumor contained pancreatic polypeptide and pancreatic cancer-associated antigen. This case represents a rare syndrome due to an as yet undefined peptide secreted by a (frequently malignant) pancreatic endocrine tumor and masquerading as ZES. This is the first report of studies of pepsin secretion and of the effect of atropine, suggesting that the physiologic effects of the secretagogue resemble that of gastrin.     

Long-term efficacy and safety of omeprazole in patients with Zollinger-Ellison syndrome: a prospective study

To determine the long-term efficacy, safety, and toxicity of omeprazole, we studied 40 patients with Zollinger-Ellison syndrome given omeprazole for 6-51 mo (median 29). The mean daily dose of omeprazole required to control gastric acid secretion was 82 +/- 31 mg. Thirty-one patients required omeprazole once per day. In 9 patients acid output was not controlled by 120 mg once per day, but was controlled by 60 mg every 12 h. The daily dose of omeprazole correlated with the previous dose of histamine H2-receptor antagonist (r = 0.89, p less than 0.001), basal acid output (r = 0.43, p less than 0.01), and maximal acid output (r = 0.39, p less than 0.02) but not with serum concentration of gastrin (r = -0.32). Increases in the dose of omeprazole were required in 9 patients. Twenty-nine patients had mild peptic symptoms with acid outputs less than 10 mEq/h while taking histamine H2-receptor antagonists. Symptoms resolved completely in 23 patients and partially in 3 when taking omeprazole. Omeprazole prevented mucosal disease in all patients including 17 in whom histamine H2-receptor antagonists had produced only partial resolution despite acid output being less than 10 mEq/h and in those with symptoms during omeprazole therapy. Omeprazole therapy was not associated with any significant side effects, nor with any evidence of hematologic or biochemical toxicity. Serum concentrations of gastrin did not change significantly during therapy. In 6 patients treated with omeprazole for 1 yr there was no change in basal or maximal acid output. In all patients, gastric morphology and histopathology demonstrated no evidence of gastric carcinoid formation. These results demonstrate that with long-term treatment of up to 4 yr, omeprazole is safe, with no evidence of hematologic, biochemical, or gastric toxicity. Furthermore, omeprazole remained effective, with only 23% of patients requiring an increase in dose, and continued to control symptoms in patients who had not been entirely symptom-free despite high doses of histamine H2-receptor antagonists. Omeprazole is now the drug of choice in patients with Zollinger-Ellison syndrome.     

Abnormal pancreatic polypeptide release by secretin infusion in Zollinger-Ellison syndrome

In 28 patients with the Zollinger-Ellison syndrome (ZES), 26 studied before and two after tumor excision, and in 26 age-matched control patients with duodenal ulcer (DU), plasma pancreatic polypeptide and serum gastrin concentrations were studied before, during, and after infusion of pure secretin (3 CU/kg/hr). In 21 ZES patients, gastric acid output was simultaneously studied. Fasting pancreatic polypeptide concentrations were over 300 pmol/liter in five of 26 gastrinomas. In DU, secretin caused a nonsignificant increase in plasma pancreatic polypeptide concentration and markedly decreased gastric acid output. In ZES, however, it resulted in a marked increase of both plasma pancreatic polypeptide concentration and gastric acid output. Basal and post secretin pancreatic polypeptide concentrations showed no correlation with gastric acid output, serum gastrin levels, or the age of the subjects, in DU patients as well as in ZES. These concentrations were not different in ZES patients who had a vagotomy compared to nonvagotomized ZES patients. Furthermore, the pancreatic polypeptide response to intravenous secretin was abolished by gastrinoma excision.A portion of this work has appeared in abstract form (Gastroenterology 82:1161, 1982) and was presented at the Annual Meeting of the American Gastroenterological Association, Chicago (Illinois), on May 18, 1982.     

Idiopathic gastric acid hypersecretion presenting as a diarrheal disorder and mimicking both Zollinger-Ellison syndrome and Crohn's disease

Many gastric acid hypersecretory states (basal acid output of greater than 15.0 mEq/h) exist for which the etiology is known, such as Zollinger-Ellison syndrome, systemic mastocytosis, antral exclusion, antral predominant Helicobacter pylori gastritis (antral G cell hyperplasia), chronic gastric outlet obstruction, short gut syndrome and basophilic leukemias. However, many hypersecretory patients have no identified etiology for their acid hypersecretion and are designated as idiopathic gastric acid hypersecretors with a basal acid output of greater than 10 mEq/h and a normal serum gastrin level. Because of the gastric acid hypersecretion these patients also commonly have an increased frequency of stools. Idiopathic gastric acid hypersecretion represents a known cause of gastric acid hypersecretion that is far more common than Zollinger-Ellison syndrome and it has a markedly different treatment regimen and natural history. We report a case of a patient with idiopathic gastric acid hypersecretion previously misdiagnosed as having Crohn's disease because of a presenting complaint of diarrhea and mimicking Zollinger-Ellison syndrome because her fasting serum gastrin level was elevated when incorrectly measured in the presence of antisecretory treatment.     

Effectiveness of omeprazole in seven patients with Zollinger-Ellison syndrome resistant to histamine H2-receptor antagonists

The inhibitory effect of omeprazole, a benzimidazole derivative, on gastric acid secretion was investigated in seven patients with Zollinger-Ellison syndrome resistant to treatment with large doses of histamine H₂-receptor antagonists administered alone or in combination with pirenzepine. In two patients with an acute form of the syndrome, rapid control of acid overproduction was achieved with 180-mg intravenous and 120-mg oral daily doses, respectively. The other five patients, who were free of complication, initially received a standard regimen of omeprazole 60 mg orally once a day; dosage was subsequently adjusted until the basal acid output, measured 1 hr before the next dose of the drug, was less than 10 mmol/hr. The initial daily dose proved to be adequate in three patients and had to be increased to 80 mg and 60 mg bid, respectively in the remaining two patients. In all patients omeprazole therapy resulted in clinical recovery and rapid healing of mucosal lesions. The seven patients have now been followed up for 4–24 months (average 15 months). The adequacy of the daily dosage was periodically reassessed by measuring basal acid output in the hour preceding the morning dose. In one patient initially treated with 180 mg/day, dosage could be reduced to 60 mg/day. In three others, who were initially controlled with 60 mg/day, dosage had to be increased during follow-up. Despite adequate control of gastric acid secretion, one patient underwent total gastrectomy and tumor resection and another died of extensive liver metastases. The five patients still receiving omeprazole remain free of symptoms and mucosal lesions. No side effects or laboratory abnormalities ascribable to the drug were observed. It is concluded that omeprazole therapy is a good alternative in patients with Zollinger-Ellison resistant to currently available antisecretory drugs. Its safety and effectiveness in long-term therapy remain to be evaluated.