pantoprazole + bismuth + tetracycline + metronidazole

This drug is a combination therapy consisting of four active pharmaceutical ingredients: pantoprazole (a proton pump inhibitor), bismuth (typically as subcitrate or subsalicylate), tetracycline (a broad-spectrum antibiotic), and metronidazole (an antibiotic and antiprotozoal agent). This quadruple regimen is primarily used for the eradication of Helicobacter pylori infection, especially in patients who have failed standard triple therapy. Pantoprazole reduces gastric acid secretion, creating a less acidic environment that enhances the effectiveness of antibiotics against H. pylori. Bismuth compounds disrupt bacterial cell walls and may also have direct antimicrobial effects on H. pylori, while increasing the efficacy of co-administered antibiotics. Tetracycline inhibits bacterial protein synthesis by binding to the 30S ribosomal subunit, preventing growth and replication of bacteria. Metronidazole acts by damaging bacterial DNA through reduction-activated cytotoxic intermediates, leading to cell death[1][5][8]. The combination targets multiple pathways in H. pylori survival and colonization, making it effective even when resistance to other regimens has developed.