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.

Inclusion Criteria:

• Patients must be men or nonpregnant women at least 18 years of age
• Patients who present with a gastric or duodenal ulcer (major dimension of the ulcer must be ≥ 5 mm and ≤ 20 mm) with endoscopic appearance of spurting, oozing, or nonbleeding visible vessel (NBVV) Patients presenting with adherent protruding clot are eligible if, after removal of the clot by irrigation, the underlying lesion is classified as spurting, oozing or a NBVV. Patients with an actively bleeding ulcer or a NBVV within a hiatal hernia are eligible if the ulcer is located below the Z-line)

Exclusion Criteria:

• Patients with ulcer appearance of clean base (non-oozing, non-spurting) or flat pigmented spot; adherent clots not removed by irrigation
• Patients presenting with active bleeding and/or NBVV at 2 or more separate sites
• Patients with any severe concomitant diseases, eg, end-stage liver or renal disease, or unstable cardiovascular, pulmonary, renal, hepatic, or gastrointestinal diseases