Medical management of patients with Zollinger-Ellison syndrome who have had previous gastric surgery: a prospective study

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.(ABSTRACT TRUNCATED AT 250 WORDS)

Review article: the management of Zollinger-Ellison syndrome

Awareness of the sometimes subtle features of Zollinger-Ellison syndrome is important in order not to miss the diagnosis. Immediately after initial diagnostic tests, the patient should be given antisecretory medication, while tests for the type of Zollinger-Ellison syndrome and tumour extent can be delayed. Acid output should be decreased to < 10 mmol/h to control symptoms and prevent complications. Histamine H2-antagonists remain the best available intravenous therapy but omeprazole is the most effective long-term oral therapy and has proved to be safe in nearly 10 years of continuous use. The management of the gastrinoma has changed in recent years since the discovery that the majority of gastrinomas arise outside the pancreas. Exploratory surgery with tumour resection is the treatment of choice in sporadic Zollinger-Ellison syndrome but there are few indications for surgery in patients with Zollinger-Ellison syndrome and multiple endocrine neoplasia type-1. None of the available therapies for metastatic gastrinoma is very effective.

Control of gastric acid hypersecretion in the management of patients with Zollinger-Ellison syndrome

During the last 5 years important advances have occurred in the control of gastric acid hypersecretion in Zollinger-Ellison syndrome (ZES). The increased availability of potent gastric acid antisecretory agents such as histamine H2-receptor antagonists and more recently the H+K(+)-ATPase inhibitors such as omeprazole and lansoprazole have made it possible to medically control acid secretion in all patients. Increased understanding of the variation in antisecretory drug dosage between individual patients has led to identification of criteria to ensure effective antisecretory control and to the recognition of subgroups of patients who require special monitoring. Effective regimens for parenteral antisecretory control during surgery have been established. The importance of parathyroidectomy in patients with multiple endocrine neoplasia type I with ZES and the possible usefulness of highly selective vagotomy have been investigated. We review here the new data that led to increased understanding in each of these areas from our studies and studies by others.

Efficacy of long-term therapy with low doses of omeprazole in the control of gastric acid secretion in Zollinger-Ellison syndrome patients

Thirteen patients with Zollinger-Ellison syndrome were investigated: 8 without, and 5 with, previous gastric surgery. After 7-34 months of treatment with famotidine, 8 out of 13 patients were resistant to this drug. Omeprazole 60 mg/day was administered to these 8 patients; after one month, the dose was reduced to 40 mg/day, and after another month to 20 mg/day. Basal acid secretion was inhibited by every dose of omeprazole. The patients were then treated with a low dose (20 mg/day) of omeprazole for a longer period. Periodic clinical and endoscopic assessments, and measurement of basal acid secretion showed the efficacy of this low dose of omeprazole in our Zollinger-Ellison syndrome patients. The drug was discontinued after 12-32 months of omeprazole treatment, and gastric acid recovery was evaluated. Four patients recovered 50% of their 'initial basal acid secretion' after 5 days, while two patients who had been treated with omeprazole for a longer time (30-32 months) recovered only 38 and 40%, respectively, of their 'initial basal acid secretion' at the tenth day. Our results indicate that the omeprazole dosage to be used in the treatment of Zollinger-Ellison syndrome must be chosen principally on the basis of basal acid secretion determination. A low daily dose of omeprazole is able to control acid secretion in Zollinger-Ellison syndrome for a long period (10-30 months). The slow recovery of gastric secretory function demonstrates the prolonged inhibitory effects of omeprazole.

Prospective study of efficacy and safety of lansoprazole in Zollinger-Ellison syndrome

Lansoprazole, a new substituted benzimidazole H+,K(+)-ATPase inhibitor, profoundly inhibits gastric acid secretion and has potential use in the management of diseases such as Zollinger-Ellison syndrome (ZES). In the present study we evaluated the efficacy and safety of lansoprazole in controlling acid hypersecretion in 20 patients with ZES. The starting dose was 60 mg once daily. Control of acid hypersecretion was defined as the dose required to reduce acid secretion to < 10 meq/hr in the last hour before the next dose. Doses were adjusted upwards until effective control was achieved. Patients not controlled with 120 mg once daily were placed on twice daily lansoprazole. Most patients (90%) required lansoprazole once daily. During long-term follow-up (mean 18.5 months), 25% of patients required upward dose adjustments and 25% of patients required twice daily lansoprazole. Following cessation of therapy, the mean time for gastric acid output to reach half basal acid output was 39.1 hr. Lansoprazole was well-tolerated without side effects. Clinical chemistry and hematological studies were unchanged, and no gastric carcinoids developed. These results demonstrate that lansoprazole is a safe and effective inhibitor of gastric acid hypersecretion in patients with Zollinger-Ellison syndrome. Because it has a long duration of action, lansoprazole can be used to control gastric acid hypersecretion in most patients with Zollinger-Ellison syndrome using a once daily dosing schedule.

Prospective study of the long-term efficacy and safety of lansoprazole in patients with the Zollinger-Ellison syndrome

The long-term safety and efficacy of lansoprazole were studied in 21 patients with Zollinger-Ellison syndrome. The initial maintenance dose was determined by acid inhibition studies. In all patients lansoprazole controlled gastric acid hypersecretion and peptic symptoms in both the short and long term. Patients were treated for a mean of 31 months (range 1-43 months) with all but 4 patients followed for > 18 months. The mean initial dose was 60 mg/day, with 2 patients requiring a twice daily dose and the others a single daily dose. During long-term treatment 6 patients required an increased dosage, 5 within the first year. Long-term maintenance doses were reduced in 5 of the 6 patients in whom this was attempted. No changes in serum gastrin concentration, haematological parameters, liver function studies or other biochemical parameters occurred due to lansoprazole. No patient developed a gastric carcinoid tumour while being treated with lansoprazole. These results demonstrate that long-term treatment with lansoprazole is both safe and effective in patients with Zollinger-Ellison syndrome, and suggest that this drug will be useful in such patients. Furthermore, maintenance doses of lansoprazole, determined by the currently recommended method of acute acid titration studies in patients with Zollinger-Ellison syndrome, are too high.

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.

Effects of curative gastrinoma resection on gastric secretory function and antisecretory drug requirement in the Zollinger-Ellison syndrome

The chronic hypergastrinemia in diseases such as the Zollinger-Ellison syndrome has trophic effects on the gastric mucosa, causing increased parietal cell mass reflected by increased maximal acid output (MAO) and basal acid output (BAO). The time course for the development of these gastric changes in humans is unknown, and controversy exists regarding whether reversal of the hypergastrinemia results in rapid normalization of gastric secretory function. To address these uncertainties, gastric secretory function was prospectively evaluated in 20 patients with the Zollinger-Ellison syndrome undergoing successful curative resection of gastrinoma. Each patient had gastric acid measurements, imaging studies, fasting serum gastrin and secretin provocative testing preoperatively, postoperatively at 3-6 months, and yearly thereafter. Preoperative mean BAO was 39 mEq/h, MAO 56 mEq/h, BAO-MAO ratio 0.73, and fasting gastrin output 1020 pg/mL. All patients were evaluated at 6 months, 17 at 1 year, 15 at 2 years, 13 at 3 years, and 9 at 4 years. By 3-6 months, MAO decreased by 50% in men (mean, 30 mEq/h) and by 35% in women (mean, 29 mEq/h) and then remained relatively unchanged for up to 4 years. Before surgery, 14 of 20 patients (70%) had an elevated MAO, whereas 4 years after resection, none of 9 patients had elevated levels. By 3-6 months, BAO decreased by 75% and remained unchanged for up to 4 years. At 3-6 months, 56% of patients were mild hypersecretors and 67% remained hypersecretors up to 4 years. Preoperatively, the BAO-MAO ratio was elevated in 16 of 20 patients (80%); postoperatively, only 5 of 18 patients (28%) at 3-6 months, 2 of 15 (13%) at 1 year, and 2 of 10 (20%) at 4 years continued to have elevated ratios. Preoperatively, the mean ranitidine dose was 1597 mg/day, whereas after surgery the mean dose was 535 mg/day at 3-6 months and approximately 300 mg/day at 1-4 years with 8 patients requiring no antisecretory drug. These results show that the trophic effects of chronic hypergastrinemia are, in general, rapidly reversible with a 50% decrease in MAO within 3-6 months of cure. Similarly, BAO decreased by 75% within 3-6 months. Despite these decreases, careful monitoring of acid secretion is required after reversal of the chronic hypergastrinemia in diseases such as the Zollinger-Ellison syndrome, because 55% of patients at 3-6 months and up to 67% at 4 years continue to remain mild hypersecretors and require low doses of antisecretory drugs.

Curative resection in Zollinger-Ellison syndrome. Results of a 10-year prospective study

Since 1980, 73 patients with Zollinger-Ellison syndrome (ZES) without radiographic evidence of liver metastases were studied on a prospective protocol including medical management of gastric acid hypersecretion, extensive radiographic tumor localization, and exploratory surgery to find and resect gastrinoma for potential cure. Each patient had gastric acid hypersecretion effectively controlled with either H2-blockers or omeprazole. Patients were divided prospectively into two groups, with all patients undergoing the same preoperative localization studies and extensive laparotomy. In contrast to group 1 (1980-1986) (36 patients), group 2 (1987-Oct. 1990) (37 patients) also underwent additional procedures (transillumination and duodenotomy) at surgery to find duodenal gastrinomas. Preoperative imaging studies localized tumor in 38 (52%) patients, and portal venous sampling for gastrin determinations was positive in 49 (67%) patients. Gastrinomas were found and resected in 57 (78%) patients. Significantly more gastrinomas (92% of patients) were found in group 2 than in group 1 patients (64%) (p less than 0.01). This increase was due to increased numbers of duodenal gastrinomas in group 2 than in group 1 patients (43% versus 11%; p less than 0.01). The increased ability to find duodenal gastrinomas did not significantly improve the immediate disease-free rate, which was 58% for all patients. Duodenal primary gastrinomas were found to have a significantly greater incidence of metastases (55%) and a significantly shorter disease-free interval (12 months) than pancreatic gastrinomas (22% and 84 months, respectively) suggesting that duodenal gastrinomas may be more malignant and not more frequently curable than pancreatic gastrinomas. Operations were performed with no deaths and 11% morbidity rate. Long-term follow-up showed that 50% of patients initially rendered disease free would develop recurrent disease by 5 years. Survival was excellent for all patients, and none died of malignant spread of the tumor or uncontrolled peptic ulcer disease, with a mean follow-up of 5 years. This finding is in contrast to patients who presented with metastatic disease on imaging studies and had a 20% 5-year survival rate. This study suggests that all patients with localized sporadic ZES can have the gastric acid hypersecretion managed medically, that overall survival of these patients is excellent, most (78%) can have all gastrinoma found and resected, and some (30%) will be cured (long-term disease-free survival).

APUDomas: acute complications and their medical management

APUDomas are rare tumours originating from a variety of endocrine cells localized in different organs. Acute complications from APUDomas usually result from the increased biosynthesis and release of bioactive amines or polypeptide hormones by the tumour. Less frequently, bleeding or compression by the tumour can occur requiring emergency surgery. Increased gastrin production by gastrinomas is the cause of ZES (peptic ulceration and diarrhoea) by gastrin effects on gastric acid secretion. Volume depletion, hypokalaemia, severe bleeding, duodenal perforation, oesophageal stricture and pyloric stenosis are the most dramatic complications. Treatment of these complications and their prevention has been facilitated by the availability of antagonists to H2 receptors and H(+)-K+ proton pump. These medications should control acid output in every patient with ZES. Frequent manifestations of carcinoid tumours, VIPomas and medullary thyroid carcinomas are flushing and diarrhoea. Octreotide, a long-acting somatostatin analogue, has markedly changed the management of these patients, their symptoms decreasing in severity or disappearing in most cases. Octreotide has also been used with success in the prevention and treatment of the carcinoid crisis, a dreaded complication of carcinoid tumours. A better understanding of the pathophysiology of APUDomas has enabled new treatment designs which have considerably ameliorated the quality of life of patients affected by these tumours; efforts must be continued to affect their life expectancy.

Thyrotropin-releasing hormone-immunoreactive projections to the dorsal motor nucleus and the nucleus of the solitary tract of the rat

Thyrotropin-releasing hormone-immunoreactive nerve terminals heavily innervate the dorsal motor nucleus and nucleus of the solitary tract, whereas cell bodies containing thyrotropin-releasing hormone residue most densely in the hypothalamus and raphe nuclei. By using double-labeling techniques accomplished by retrograde transport of Fluoro-Gold following microinjection into the dorsal motor nucleus/nucleus of the solitary tract combined with immunohistochemistry for thyrotropin-releasing hormone, it was demonstrated that thyrotropin-releasing hormone-immunoreactive neurons projecting to the dorsal motor nucleus/nucleus of the solitary tract reside in the nucleus raphe pallidus, nucleus raphe obscurus, and the parapyramidal region of the ventral medulla, but not in the paraventricular nucleus of the hypothalamus. The parapyramidal region includes an area along the ventral surface of the caudal medulla, lateral to the pyramidal tract and inferior olivary nucleus and ventromedial to the lateral reticular nucleus. Varying the position of the Fluoro-Gold injection site revealed a rostral to caudal topographic organization of these raphe and parapyramidal projections.

Omeprazole. An updated review of its pharmacology and therapeutic use in acid-related disorders

Omeprazole is the first of a new class of drugs, the acid pump inhibitors, which control gastric acid secretion at the final stage of the acid secretory pathway and thus reduce basal and stimulated acid secretion irrespective of the stimulus. In patients with duodenal or gastric ulcers, omeprazole as a single 20 mg daily dose provides more rapid and complete healing compared with ranitidine 150 mg twice daily or 300 mg at nighttime, or cimetidine 800 or 1000 mg/day. Patients poorly responsive to treatment with histamine H2-receptor antagonists respond well to omeprazole--most ulcers healed within 4 to 8 weeks of omeprazole 40 mg/day therapy. Omeprazole 20 or 40 mg/day has been administered as maintenance therapy for peptic ulcer disease for up to 5.5 years with very few ulcer recurrences. In patients with erosive or ulcerative oesophagitis, omeprazole 20 or 40 mg/day produces healing in about 80% of patients after 4 weeks, and is superior to ranitidine with respect to both healing and symptom relief. Healing rates of greater than 80% are achieved after 8 weeks in patients with severe reflux oesophagitis unresponsive to H2-receptor antagonists. Maintenance therapy with a daily 20 mg dose prevents relapse in about 80% of patients over a 12-month period. Omeprazole is considered to be the best pharmacological option for controlling gastric acid secretion in patients with Zollinger-Ellison syndrome. Daily dosages of 20 to 360 (median 60 to 70 mg successfully reduce basal acid output to target levels (less than 10 mmol/h or less than 5 mmol/h in patients with severe oesophagitis or partial gastrectomy) during treatment for up to 4 years. Omeprazole is well tolerated in short term studies (up to 12 weeks); the reported incidence of serious side effects (about 1%) being similar to that seen in patients treated with an histamine H2-receptor antagonist. The longer term tolerability of omeprazole has been investigated in patients treated for up to 5.5 years. Slight hyperplasia, but no evidence of enterochromaffin-like (ECL) cell dysplasia or neoplasia or ECL cell carcinoids has been reported. ECL cell carcinoids have been observed in rats after life-long treatment with high doses of omeprazole or ranitidine, or in rats with partial corpectomy; the weight of experimental evidence indicates that this is a result of prolonged hypergastrinaemia.(ABSTRACT TRUNCATED AT 400 WORDS)

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.

Representation of the cecum in the lateral dorsal motor nucleus of the vagus nerve and commissural subnucleus of the nucleus tractus solitarii in rat

Motor fibers of the accessory celiac and celiac vagal branches are derived from the lateral columns of the dorsal motor nucleus of the vagus nerve. These branches also contain sensory fibers that terminate within the nucleus of the tractus solitarii. This study traces the innervation of the intestines by using the tracer cholera toxin-horseradish peroxidase. In 53 rats, the tracer was injected into either the stomach, duodenum, jejunum, terminal ileum, cecum, or ascending colon. With all cecal injections, prominent retrograde labeling of cell bodies occurred bilaterally in the lateral columns of the dorsal motor nucleus of the vagus nerve above, at, and below the level of the area postrema. Dendrites of laterally positioned neurons projected medially and rostrocaudally within the dorsal motor nucleus of the vagus nerve and dorsomedially into both the medial subnucleus and parts of the commissural subnucleus of the nucleus of the tractus solitarii. Sensory terminal labeling occurred in the dorsolateral commissural subnucleus at the level of the rostral area postrema and the medial commissural subnucleus caudal to the area postrema. Additionally, there was sensory terminal labeling within a small confined area of the dorsomedial zone of the nucleus of the tractus solitarii immediately adjacent to the fourth ventricle at a level just anterior to the area postrema. Stomach injections labeled motoneurons of the medial column of the entire rostrocaudal extent of the dorsal motor nucleus of the vagus nerve and a sensory terminal field primarily in the subnucleus gelatinosus, with less intense labeling extending caudally into the medial and ventral commissural subnuclei. Dendrites of gastric motoneurons project rostrocaudally and mediolaterally within the dorsal motor nucleus of the vagus nerve and dorsolaterally within the nucleus of the tractus solitarii. They are most pronounced at the level of the rostral area postrema where many dendrites course dorsolaterally terminating primarily within the subnucleus gelatinosus. Injections of the duodenum labeled a small number of the cells within the medial aspects of the dorsal motor nucleus of the vagus nerve. Jejunal, ileal, and ascending colon injections labeled cells sparsely within the lateral aspects of the dorsal motor nucleus of the vagus nerve bilaterally. No afferent terminal labeling was evident after injection of these areas of the bowel.(ABSTRACT TRUNCATED AT 400 WORDS)

Omeprazole. Gastrin and gastric endocrine cell data from clinical studies

Gastric enterochromaffin-like cell carcinoids have been detected in rats exposed lifelong to omeprazole. By inhibiting acid secretion, omeprazole causes hypergastrinemia which, with prolonged exposure, exerts a trophic effect on enterochromaffin-like cells with eventual enterochromaffin-like cell carcinoid formation in some animals. This mechanism seems to explain the appearance of enterochromaffin-like cell carcinoids in human hypergastrinemic states, whether associated with hyperchlorhydria, eg, Zollinger-Ellison syndrome, or with hypochlorhydria, eg, pernicious anemia (nonantral atrophic gastritis). Omeprazole produces modest serum gastrin elevations in humans when monitored over a 24-hr period. Gastrin levels are markedly lower and less sustained than in the above hypergastrinemic states. Extensive gastric biopsy data from patients enrolled in long-term studies indicate that omeprazole administration is not associated with clinically significant changes in the human oxyntic endocrine cell population. Man and rat differ markedly both in their gastrin response to a given level of acid inhibition and in their response to the trophic influence of gastrin on enterochromaffin-like cells. The rat model is a false indicator of risk in man.

Peptic ulcer perforation as the presentation of Zollinger-Ellison syndrome

We examined the characteristics of patients with Zollinger-Ellison syndrome who developed a perforation prior to diagnosis to determine whether any clinical features were useful markers of the syndrome. Of 160 patients with Zollinger-Ellison syndrome, perforation occurred prior to the diagnosis being made in 11 (7%). At surgery, perforations were found in the duodenum in six cases and in the jejunum in five. In no case was tumor identified at emergency surgery, and the diagnosis of Zollinger-Ellison syndrome was made only in the postoperative period when excessive gastric secretions were noted. Neither acid output nor serum gastrin concentration were useful predictors for perforation. The patients, six men and five women, were 27-61 years old (median 48) and one had MEN-1. Three patients had no symptoms prior to the perforation. The other eight had symptoms for 1-15 years, with diarrhea occurring in 45% of the cases. Following the diagnosis of Zollinger-Ellison syndrome, patients were given medication to control gastric acid hypersecretion. Eight patients remained well, but the three patients who had had a partial gastrectomy had a complicated course despite medical therapy. Although features of perforation in Zollinger-Ellison syndrome are not specific, jejunal perforation or perforation associated with a history of diarrhea is suggestive of the diagnosis. Serum gastrin should be measured in every case and a partial gastrectomy avoided.

Therapeutic strategies in the management of endocrine GEP tumours

The therapeutic principles in the management of endocrine gastroenteropancreatic (GEP) tumours include surgical extirpation of the primary tumour in the absence of metastases and medical control of symptoms in the preoperative phase. In the presence of metastases only palliative procedures are available. Tumour growth might be controlled by surgical procedures as debulking of tumour masses, medically by chemotherapy and more recently by new developments as a long-acting somatostatin analogue (SMS 201-995) and alpha-interferon. Their efficacy is currently evaluated in prospective studies. In contrast to inhibition of growth symptoms derived from excessive hormone production by GEP tumours can be well controlled. SMS 201-995 effectively prevents or at least improves flush and diarrhoea in the carcinoid syndrome, disabling diarrhoea in the Verner-Morrison syndrome and migratory erythema in the glucagonoma syndrome. SMS acts by inhibition of hormone release from the tumour and by a direct mechanism at the site of the target cell via SMS receptors present on tumour and target cells. For control of acid hypersecretion in gastrinoma patients omeprazole is superior to all former and present alternatives and replaced total gastrectomy completely. A similarly effective drug to prevent hypoglycaemia due to uncontrolled insulin release from insulinomas is not available since neither SMS nor diazoxide are effective in every insulinoma patient.

Antagonistic effect of human alpha-CGRP [8-37] on the in vivo regional haemodynamic actions of human alpha-CGRP

In conscious rats, infusion of human alpha-CGRP [8-37] (30 nmol/kg/min) caused small, reversible reductions in hindquarters flow and vascular conductance only, whereas at a dose of 300 nmol/kg/min there was a tachycardia and an increase in mean arterial blood pressure, together with renal, mesenteric and hindquarters vasoconstrictions. Human alpha-CGRP (0.03 nmol/kg/min) caused tachycardia, hypotension, and transient renal, but sustained hindquarters, vasodilatation; these changes were accompanied by mesenteric vasoconstriction. Infusion of human alpha-CGRP [8-37] (30 nmol/kg/min) during administration of human alpha-CGRP (0.03 nmol/kg/min) abolished the effects of the latter but these re-appeared when the human alpha-CGRP [8-37] infusion was stopped. This dose of human alpha-CGRP [8-37] did not affect cardiovascular responses to isoprenaline. These results indicate that human alpha-CGRP [8-37] is an effective antagonist of the cardiovascular actions of human alpha-CGRP in vivo.

Intravenous omeprazole in patients with Zollinger-Ellison syndrome undergoing surgery

Twenty patients with Zollinger-Ellison syndrome who were undergoing surgery were studied prospectively to assess the efficacy and safety of IV omeprazole. During the preoperative period, in 19 of 20 patients, omeprazole 60 mg administered as an IV bolus every 12 hours inhibited acid output to less than 5 mEq/h measured in the last hour before the next dose of drug. In one patient, acid output was 25 mEq/h 12 hours after omeprazole, 60 mg, and increasing the dose to 100 mg every 12 hours reduced acid output to less than 5 mEq/h. During the operative and postoperative periods, IV omeprazole controlled gastric acid hypersecretion in all patients for up to 15 days. During this time, all patients received the dose determined preoperatively. No patient developed any clinical, hematological, or biochemical toxicity that could be attributed to omeprazole therapy during the preoperative or postoperative period. The present study demonstrates that omeprazole administered by IV bolus is safe and effective for controlling gastric acid hypersecretion. In contrast to IV histamine H2-receptor antagonists, IV omeprazole has the advantages of not requiring continuous infusion or postoperative dose adjustments. Intravenous omeprazole will become the drug of choice in patients with Zollinger-Ellison syndrome undergoing surgery.

Quantitative ultrastructure of endocrine cells of oxyntic mucosa in Zollinger-Ellison syndrome. Correspondence with light microscopic findings

The endocrine cells of the oxyntic mucosa of five patients with longstanding Zollinger-Ellison syndrome were quantitatively investigated with electron microscopy and two light microscopic methods (Grimelius and immunostaining for chromogranin A). Ultrastructurally, the volume density of endocrine cells was 3.2% +/- 1.1% of the mucosal epithelial component, a 168% increase (P less than 0.001) over the value found in normal subjects. Of the six endocrine cell types of human oxyntic mucosa, only enterochromaffinlike cells increased in cell density (65% +/- 15% of the total endocrine cell mass), size, and number of cell profiles per unit area. The enterochromaffinlike cells also underwent morphological changes of secretory granules with a decrease in vacuolated forms, increase in elongated profiles, and appearance of granules with a punctate structure of the core. The latter variety of granules was previously observed only in carcinoid tumors of the oxyntic mucosa and is possibly related to the enterochromaffinlike cell hyperplasia-neoplasia sequence seen in hypergastrinemic patients. A positive relationship was found between endocrine cell densities evaluated ultrastructurally and with chromogranin A immunostaining. It is concluded that in Zollinger-Ellison syndrome, the trophic effects induced by longstanding hypergastrinemia are strictly selective for enterochromaffinlike cells and are associated with ultrastructural features typical for enterochromaffinlike cell tumors.

Reflux esophagitis in patients with Zollinger-Ellison syndrome

The incidence of ulcers of the stomach and duodenum and their response to medical therapy, in patients with Zollinger-Ellison syndrome is well described. However, reflux esophagitis is less well recognized. In this study we determined the frequency of reflux esophagitis in 122 patients with Zollinger-Ellison syndrome and examined their response to medical therapy. Esophageal symptoms, endoscopic abnormalities, or both were present in 61% of patients. Forty-five percent of patients had esophageal symptoms consisting of heartburn, dysphagia, or both. Forty-three percent of patients had endoscopic abnormalities of the esophagus, and 23% demonstrated moderate or severe disease. When sufficient antisecretory medication was administered to lower gastric acid secretion to less than 10 mEq/h in the last hour before the next dose of drug, 67% of the patients with reflux esophagitis responded with complete disappearance of symptoms and normalization of the endoscopic abnormalities. The other 33% of patients required an increase in medication to lower acid output to less than 5 mEq/h in 7% and less than 1 mEq/h in the other 26% to resolve symptoms and signs completely. We conclude that reflux esophagitis occurs in the majority of patients with Zollinger-Ellison syndrome and responds well to medical therapy, although one third of patients require intensive antisecretory medication.

APUD update

Apudomas are a diffuse group of tumors that have interested surgeons for a long time. With recent developments in their radiological localization and pharmacological control, they are now treated in a truly multidisciplinary approach. In this chapter, recent developments in the radiological, surgical, and medical approaches to these tumors are reviewed. Emphasis is placed on how non-surgical developments have affected the surgical treatment of specific apudomas. Resulting changes in surgical philosophy are also reviewed.

Zollinger-Ellison Syndrome in the Intensive Care Setting

Management of patients with Zollinger-Ellison syn drome differs markedly from management of patients with idiopathic gastric acid hypersecretion or routine peptic ulcer disease. Because of the possible complica tions arising from gastric acid hypersecretion or from complications caused by the gastrinoma itself, patients with these disorders frequently present to critical care physicians. It is important that critical care physicians be familiar with the acute presentation of patients with Zollinger-Ellison syndrome as well as the appropriate treatment. We review the important points pertaining to the recognition and treatment of Zollinger-Ellison syn drome in the acute care setting.

Famotidine. An updated review of its pharmacodynamic and pharmacokinetic properties, and therapeutic use in peptic ulcer disease and other allied diseases

Famotidine is a highly selective histamine H2-receptor antagonist. In healthy volunteers and patients with acid hypersecretory disease it is approximately 20 to 50 times more potent at inhibiting gastric acid secretion than cimetidine and 8 times more potent than ranitidine on a weight basis. As shown in placebo-controlled trials, famotidine is effective in healing both duodenal and gastric ulcers. Famotidine 20mg twice daily or 40mg at bedtime achieves healing rates and symptom relief similar or superior to those achieved by cimetidine 800mg daily or ranitidine 300mg daily in patients with peptic ulcer disease. Results of 1 placebo-controlled study suggest that famotidine prevents recurrence of duodenal ulcer, but comparative trials are needed to establish its relative efficacy in maintenance therapy. The few non-comparative trials conducted to date also suggest that famotidine 10 to 20mg twice daily may be effective in the treatment of gastritis and reflux gastro-oesophagitis. In comparative trials, famotidine was similar in efficacy to cimetidine in the treatment of upper gastrointestinal bleeding and to ranitidine in the prevention of pulmonary aspiration of acid. In patients with Zollinger-Ellison syndrome, the potency and long duration of action of famotidine may confer an advantage over other H2-receptor antagonists--in individualised doses (mean 0.33 g/day) famotidine successfully controlled acid secretion for up to 72 months in 1 study of such patients. Accumulated clinical evidence confirms that famotidine is very well tolerated and is free of the antiandrogenic effects infrequently reported with cimetidine. Moreover, famotidine is not associated with altered hepatic metabolism of drugs. Thus, famotidine is an effective, well-tolerated alternative to cimetidine and ranitidine. Famotidine is also promising as maintenance therapy for preventing recurrence of duodenal ulcer and as initial or maintenance treatment of gastric hypersecretory disorders, but further clinical experience, particularly in the long term, is needed to define the relative efficacy and tolerability of famotidine in these indications.

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.

Diagnosis and management of Zollinger-Ellison syndrome

With the recent widespread availability of gastrin radioimmunoassays, the development of increasingly effective medical therapy for gastric hypersecretion, and improved methods to localize gastrinomas in patients with Zollinger-Ellison syndrome, the diagnosis, treatment of the gastric acid hypersecretion, and approach to the tumor have changed significantly. Recent advances in each of these areas and the current management of a patient with Zollinger-Ellison syndrome are reviewed.

Parenteral antisecretory drug therapy in patients with Zollinger-Ellison syndrome

Forty-six patients with Zollinger-Ellison syndrome were studied prospectively to determine a safe and effective method and criterion for controlling gastric acid hypersecretion during periods when oral antisecretory agents could not be used. In each patient it was possible to reduce acid secretion to less than or equal to 10 mEq/h after an i.v. bolus of 150 or 300 mg of cimetidine and a stepwise titration of cimetidine given by continuous infusion. The mean dose given by i.v. infusion was 2.9 mg/kg body wt.h but there was a wide range (0.5-7.0 mg/kg body wt.h) and the minimal dose had to be determined individually for each patient. The minimal i.v. cimetidine dose did not correlate with basal or maximal acid output or fasting gastrin concentration, but correlated closely with either the previous oral dose of cimetidine (r = 0.96, p less than 0.001) or the previous oral dose of ranitidine or famotidine (r = 0.95, p less than 0.001). To study the efficacy and safety of an i.v. infusion of cimetidine, 34 patients undergoing surgery were maintained on i.v. cimetidine for a mean of 12 days (range 1-83 days). One-half of the patients did not require dose adjustment, whereas the remainder required an average of 2 adjustments, usually in the first 3 postoperative days. No patient developed complications attributable to gastric acid hypersecretion in the postoperative period, and there was no detectable neurologic, hematologic, or hepatic toxicity. This study demonstrates that a continuous i.v. infusion of cimetidine adequately inhibits gastric acid hypersecretion in patients with Zollinger-Ellison syndrome. However, high doses were frequently required, the dose had to be determined in a stepwise fashion individually for each patient, and the i.v. dose correlated with the previous oral dose. Reducing acid secretion to less than or equal to 10 mEq/h was a safe criterion during surgery and continuous i.v. cimetidine was safe and effective in achieving this degree of control for up to 83 days.

Gastrinoma. New medical and surgical approaches

The clinical presentation of gastrinoma has changed since the original description by Zollinger and Ellison in 1955. Tumors currently found are smaller, extrapancreatic or extraintestinal in location, and frequently occult within lymph nodes. The incidence of hepatic metastases on initial presentation has decreased. In addition, the clinical course of patients with tumor in lymph nodes is benign, suggesting that more patients than were previously thought are now candidates for cure. Improved knowledge of the anatomic location of gastrinomas has enhanced our ability to find and remove them at laparotomy. As a result of these factors, more patients are being cured than ever before, and in the future, cure rate may be even higher. On the basis of these recent advances, the optimal treatment of gastrinoma is surgical excision for cure.