This is a multicenter, randomized, double-blind, parallel-group, dose-ranging, comparator-controlled study of the effect of pantoprazole on intragastric pH after successful endoscopic hemostasis in hospitalized patients. Patients will receive either intravenous pantoprazole (one of two regimens) or ranitidine (the comparator) within 2 hours of successful hemostasis and administration will continue for 72 hours after hemostasis.