esomeprazole + bismuth + metronidazole

This is a combination drug regimen consisting of esomeprazole (a proton pump inhibitor), bismuth (typically as bismuth subcitrate or subcitrate potassium, an inorganic salt with antimicrobial and mucosal protective properties), and metronidazole (a nitroimidazole antibiotic). This combination is used as part of a quadruple therapy for the eradication of Helicobacter pylori infection, which is associated with peptic ulcer disease. Esomeprazole reduces gastric acid secretion by inhibiting the H+/K+ ATPase in gastric parietal cells, creating a less acidic environment that enhances antibiotic efficacy. Bismuth compounds exert direct bactericidal effects against H. pylori and protect the gastric mucosa. Metronidazole disrupts DNA synthesis in susceptible bacteria, including anaerobes like H. pylori. This regimen may be used when tetracycline or amoxicillin are unavailable or contraindicated[4]. The primary indication is for first-line treatment of H. pylori infection to prevent recurrence of peptic ulcers.