Immune hemolytic anemia due to cimetidine: the first example of a cimetidine antibody

BACKGROUND: Although there have been a few reports of immune hemolytic anemia (IHA) thought to be due to cimetidine, none of them provided proof (e.g., serologic detection of anti-cimetidine and/or repeat of IHA upon drug rechallenge). One report used cimetidine as an example of how temporal associations of drug administration and hemolytic anemia are not proof of a cause-effect relationship. STUDY DESIGN AND METHODS: A 63-year-old cancer patient developed IHA on two occasions after receiving cimetidine (with and without chemotherapy). Serologic methods included testing cimetidine-treated red blood cells (RBCs) as well as testing untreated RBCs in the presence of cimetidine. RESULTS: The patient's direct antiglobulin test was positive (C3 only) and a serum antibody to cimetidine was detected by both testing methods. An eluate from the patient's RBCs was nonreactive. Cimetidine-treated RBCs were optimally prepared at room temperature and needed to be tested on the day of preparation. CONCLUSIONS: This is the first reported case of IHA due to a cimetidine antibody where a drug-dependent antibody was demonstrated. The patient had IHA after receiving cimetidine on two separate occasions.