PARENTERAL CONTROL OF GASTRIC-ACID HYPERSECRETION IN PATIENTS WITH ZOLLINGER-ELLISON SYNDROME

Parenteral control of gastric acid hypersecretion in patients with Zol linger-Ellison syndrome is increasingly required; however, existing me thods of determining the required dose are cumbersome and not applicab le in all centers. A previous study suggested that the required parent eral dose of histamine H-2-receptor antagonists correlated with the pr evious oral dose. In the present study, in 31 patients with Zollinger- Ellison syndrome we evaluated the hypothesis that an effective parente ral histamine H-2-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 patie nts 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% 25 mg/kg/hr. This dose of ranitidine acu tely controlled acid secretion (< 10 meq/hr) in all patients. To evalu ate 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 bio chemical, clinical, or hematological toxicity was seen, although ranit idine was stopped in one patient because of skin rash. These results d emonstrate that the parenteral dose of ranitidine required to control acid secretion in patients with Zollinger-Ellison syndrome can be pred icted from the oral dose. This predicted dose will be acutely effectiv e in all patients in reducing acid secretion to <10 meq/hr, the establ ished level of control, will remain effective in 95% of patients for u p to 11 days, and is safe. By utilizing the oral dose to predict the i ntravenous dose, repeated dose titrations will be avoided and thus thi s method should be generally useful in all settings.