A 52-year-old man from Delhi presents with a 3-month history of epigastric pain relieved by food and antacids. He has been a chronic user of aspirin for knee osteoarthritis. On examination, he appears pale with mild epigastric tenderness. His haemoglobin is 9.2 g/dL (MCV 72 fL), and faecal occult blood test is positive. Upper GI endoscopy reveals a 1.5 cm ulcer on the anterior wall of the first part of duodenum with visible vessel at the base. What is the most appropriate immediate management?