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

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Abstract
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.