A 34-year-old man presents with a 6-month history of intermittent epigastric pain, worse after meals and sometimes waking him at night. He occasionally uses over-the-counter antacids with temporary relief. He is a smoker and drinks 20 units of alcohol per week. A urea breath test is positive for H. pylori. He has no known drug allergies. What is the most appropriate first-line eradication therapy?