esomeprazole + tripotassium dicitrate bismuthate + amoxicillin + levofloxacin

This is a four-drug combination therapy consisting of esomeprazole, tripotassium dicitrate bismuthate (a form of bismuth subcitrate potassium), amoxicillin, and levofloxacin. It is used primarily for the eradication of Helicobacter pylori infection, especially as a second-line or rescue therapy after failure of first-line regimens. - **Esomeprazole** is a proton pump inhibitor that suppresses gastric acid secretion by irreversibly inhibiting the H+, K+-ATPase enzyme in gastric parietal cells. - **Tripotassium dicitrate bismuthate** acts as a gastroprotective agent with bactericidal activity against H. pylori; it increases mucus secretion, forms a protective barrier on ulcers, and inhibits bacterial enzymes. - **Amoxicillin** is a broad-spectrum beta-lactam antibiotic that inhibits bacterial cell wall synthesis. - **Levofloxacin** is a fluoroquinolone antibiotic that inhibits DNA gyrase and topoisomerase IV, essential enzymes for bacterial DNA replication. This quadruple regimen targets H. pylori through multiple mechanisms—acid suppression to enhance antibiotic efficacy and direct antibacterial effects from three different agents—making it effective even in cases with prior treatment failures or resistance[3][8].