Bismuth subcitrate potassium (CBS)

Bismuth subcitrate is a bismuth-containing medication primarily used to treat peptic ulcers and Helicobacter pylori infections [1, 3]. Although it is a therapeutic agent rather than a biological target, it interacts with several molecular components to exert its effects, including the inhibition of bacterial enzymes such as urease, catalase, and lipase [1, 10]. By displacing nickel ions from the active site of H. pylori urease, it disrupts the bacterium's ability to neutralize gastric acid, leading to bacterial death [1, 5]. Additionally, bismuth subcitrate forms a protective coating over the gastric mucosa by binding to mucus glycoproteins, creating a physical barrier against acid and pepsin [4, 7]. It also stimulates the endogenous production of prostaglandins and bicarbonate, which enhances mucosal defense and promotes the healing of gastric and duodenal ulcers [3, 10]. In clinical practice, bismuth subcitrate is frequently used as a component of bismuth-based quadruple therapy, often combined with antibiotics like metronidazole and tetracycline, and proton pump inhibitors like omeprazole [3, 6]. This combination is particularly effective in eradicating antibiotic-resistant H. pylori strains [3]. While generally safe, its use is associated with harmless blackening of the stool and tongue, and rare but serious safety concerns include bismuth-induced encephalopathy or nephrotoxicity if taken in excessive doses over long periods [12, 16]. Its interaction with other drugs can be significant; for instance, proton pump inhibitors can increase bismuth absorption, potentially raising the risk of systemic toxicity [2, 9].

Other names

Bismuth subcitrateColloidal bismuth subcitrateTripotassium dicitratobismuthateDe-NolPylera (component)

Bismuth subcitrate potassium acts as a bactericidal agent against Helicobacter pylori by inhibiting essential enzymes such as urease, catalase, and lipase, and by disrupting the bacterial cell wall and membrane. It also provides gastroprotective effects by forming a physical barrier (bismuth-glycoprotein complex) over ulcers and stimulating the production of mucosal prostaglandins and bicarbonate.