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.

Comparative tolerability profile of omeprazole in clinical trials.

The tolerability of omeprazole was compared to control agents in 68 clinical studies that enrolled a total of 4846 patients, of whom 3096 received omeprazole. The incidence of adverse experiences was independent of omeprazole dose administered, the age of the patients, and the disease treated (duodenal ulcer or endoscopically verified gastroesophageal reflux disease). The most common clinical adverse experiences were headache, diarrhea, abdominal pain, and nausea. The most common laboratory adverse experiences were elevated aspartate aminotransferase and elevated alanine aminotransferase. Omeprazole was well tolerated, and the incidence of clinical and laboratory adverse experiences was similar in patients receiving omeprazole, placebo, cimetidine, or ranitidine.

Failure of secretin to stimulate gastrin release and adenylate cyclase activity in gastrinoma in vitro.

It has been hypothesized that secretin may act directly on gastrinoma through the adenylate cyclase system to cause stimulation of gastrin release. We studied gastrinoma cells in vitro to determine whether secretin would stimulate gastrin release directly and whether the gastrinoma cell membrane had a functional secretin receptor adenylate cyclase system. Fresh tumor was prepared in cell suspensions containing 1.5 X 10(6) viable cells and incubated for 2 hours with either 2 mM CaCl2 alone (control) or 2 mM CaCL2 and 0.025 U/ml secretin. The gastrin content of the cells in each incubation chamber and the medium were determined by radioimmunoassay and results were expressed as mean gastrin pg/microgram protein +/- SD. Under basal conditions the cellular gastrin content was 39.9 +/- 6.4 (control) compared with 16.7 +/- 2.1 (secretin). After 2 hours of incubation, cellular gastrin content increased in both groups: 68.5 +/- 11.9 (control) to 68.3 +/- 5.5 (secretin). However, the percent of gastrin released into the medium during incubation decreased by one half in both groups (control 37.3% +/- 4.0% to 22.2% +/- 3.0%; secretin 42.8% +/- 7.0% to 18.9% +/- 1.8%). Adenylate cyclase activity was assessed by measuring cAMP generation in fresh-frozen gastrinoma and cultured gastrinoma cell membranes. Isoproterenol (10(-5) M), PGE1 (10(-4) M), and GppNHp (guanine nucleotide) (10(-5) M) caused fivefold to 25-fold increases in cAMP generation. Secretin did not stimulate adenylate cyclase activity above basal (21.73 +/- 4.07 and 2.29 +/- 1.2 pmol cAMP/mg protein/min) for frozen and cultured gastrinoma, respectively. Secretin failed to stimulate gastrin release and adenylate cyclase in vitro. This suggests that secretin-stimulated gastrin release in vivo may not be due to a direct effect of secretin on the gastrinoma.

Serum levels of alpha-1-antitrypsin in pancreatic islet cell tumors.

To evaluate the usefulness of alpha-1-antitrypsin as a tumor marker for pancreatic islet cell tumors, serum levels were measured in 16 patients including 4 with gastrinomas, 4 with glucagonomas, 1 with a malignant somatostatinoma 1 with a malignant insulinoma, and 6 with "nonfunctioning" islet cell carcinoma and in 10 controls. Serum alpha-1-antitrypsin ranged from 190-420 mg/dl in controls (normal serum values with this method range between 200-450 mg/dl). Serum levels of alpha-1-antitrypsin ranged from 150-900 mg/dl in the 16 patients with islet cell tumors. Only 3 of the 16 patients had elevated levels of alpha-1-antitrypsin. In this group of patients with advanced disease, serum alpha-1-antitrypsin was not a sensitive marker, and it is not likely to be useful for diagnostic screening or for monitoring tumor growth in patients with pancreatic islet cell tumors.

Pathophysiological responses to meals in the Zollinger-Ellison syndrome: 2. Gastric emptying and its effect on duodenal function.

In this study, we investigated the relationship between gastric emptying and duodenal events in patients with the Zollinger-Ellison syndrome due to a gastrinoma. Like the inhibitory effect of a meal on gastric secretion (described in a companion paper), postprandial inhibition of gastric emptying reduces fractional gastric emptying rates to normal during the first two hours after a meal. Gastric discharges of content into the duodenum fluctuate considerably, and, in some patients, duodenal acid load and neutralising duodenal secretions appear to be incoordinated. These mechanisms interact in part as a protective system that maintains reasonably normal duodenal homeostasis in most Zollinger-Ellison patients during the early postprandial period. Our data may explain why clinical evidence of overt-malabsorption is less prevalent and severe in these patients than would be expected from their enormously increased fasting gastric secretory outputs.

Serum group I pepsinogens by radioimmunoassay in control subjects and patients with peptic ulcer.

Serum group I pepsinogen (PG I) levels have been determined by radioimmunoassay in 924 subjects. The mean levels in 300 healthy control subjects and in 389 hospitalized controls were 110.6 and 100.0 ng per ml, respectively. The "normal" range is estimated to be between 50 and 175 ng per ml. The mean level of serum PG I in 7 patients with Zollinger-Ellison syndrome was 503.9 ng per ml; values ranged between 315 and 921 ng per ml. The 77 patients with duodenal ulcer had a mean serum PG I level of 221.3 ng per ml; 49 (63.6%) had values greater than 175 ng per ml. The distribution of serum PG I values was bimodal in the patients with duodenal ulcer whereas it was unimodal in both groups of control subjects. Mean serum PG I levels in 13 patients with both duodenal and gastric ulcer and in 18 patients with prepyloric ulcer were, respectively, 177.2 and 179.4 ng per ml. Approximately one-half of these patients had high values. The 28 patients with gastric ulcer had a mean serum PG I level of 116.6 ng per ml; 6 (21.4%) had high values. With the exception of 3 patients with gastric ulcer, none of the 136 patients with peptic ulcer had a low (less than 50 ng per ml) level of serum PG I. In 37 patients with chronic alcoholism the mean level of serum PG I was 73.4 ng per ml. The observed gradient in the mean level of serum PG I among the groups of patients studied is similar to that which has been reported for maximally stimulated gastric acid output. This finding suggests that the secretory potential of the fundic gland mucosa of the stomach may be reflected by the level of PG I in serum.