Vitamin B-12 levels during prolonged treatment with proton pump inhibitors

Reduced serum vitamin B-12 (cobalamin) levels have been documented occasion ally during long-term treatment with a proton pump inhibitor (PPI) in selec ted groups of patients. This has largely been confined to patients being tr eated for Zollinger-Ellison syndrome who have sustained drug-induced achlor hydria, which does not ordinarily occur during treatment with a PPI. An app reciation of normal cobalamin metabolism and the pharmacological action of the PPIs adequately explain the mechanism for this reduction. PPIs do not p romote the development of pernicious anemia.