An open-label study of rabeprazole in patients with Zollinger-Ellison syndrome or idiopathic gastric acid hypersecretion.

BACKGROUND: Omeprazole and lansoprazole are both of proven efficacy in the treatment of Zollinger-Ellison syndrome and idiopathic gastric acid hypersecretion. Rabeprazole, which has a similar mechanism of action, has not previously been studied in these diseases. AIM: To determine the dose of rabeprazole that decreased basal acid output to safe levels in patients with Zollinger-Ellison syndrome or idiopathic gastric acid hypersecretion. METHODS: Patients with Zollinger-Ellison syndrome or idiopathic gastric acid hypersecretion were given rabeprazole 60 mg once daily for uncomplicated disease or 40 mg twice daily for complicated disease. Doses were titrated according to response and continued for 2 years. Efficacy was assessed primarily by measuring basal acid output. RESULTS: All patients had basal acid output before the next dose controlled to <10 mmol/h either at the starting dose or after minor dose titration. Control of acid output was maintained for 2 years. Consistent with this, most patients reported few gastrointestinal symptoms. Gastric biopsy showed no enterochromaffin-like cell dysplasia or neoplasia. CONCLUSIONS: Rabeprazole was an effective and well-tolerated treatment for Zollinger-Ellison syndrome or idiopathic gastric acid hypersecretion, which reliably reduced gastric acid output to safe levels. Although a dose of 60 mg once daily was appropriate for most patients in this study, doses may need adjustment according to individual response.