Omeprazole-induced leukopenia. A case report

Background: Omeprazole has been marketed in France since 1989, for the heal ing of peptic ulcers, erosive reflux oesophagitis, and the Zollinger-Elliso n syndrome. However, the drug has been associated with serious adverse reac tions, including haemolytic anaemia and acute interstitial nephritis. More recently, an autoimmune syndrome induced by omeprazole has been described. Objective: We present here a clinical history and an in vitro test of cytot oxicity linking leukopenia to omeprazole. Results: A 37-year-old woman was hospitalized in the intensive care unit of our hospital with acute pulmonary insufficiency secondary to pneumonia. 72 h after starting omeprazole treatment, a decrease in leucocyte count was o bserved. The leukopenia was maximal on day 22: total white cell count was 2 .1 x 10(9)/l, and neutrophil count was less than 0.75 x 10(9)/l. In order t o find the cause of this leukopenia, an in vitro cytotoxicity test was perf ormed. The test was positive only when patient neutrophils and patient seru m were in the presence of omeprazole. This cytotoxicity seems to be complem ent-dependent, as in the presence of heated serum, the omeprazole toxic eff ect was substantially reduced. Conclusion: This case report suggests that the leukopenia was associated wi th omeprazole.