BACKGROUND AND OBJECTIVES: Drug-induced thrombocytopenia is a serious, but rare, side-effect of treatment with a number of drugs. In this report, we investigate the suspicion that amlodipine, a calcium-channel blocker, was responsible for immune thrombocytopenia in a 79-year-old patient. PATIENT AND METHODS: Our patient experienced two attacks of thrombocytopenic purpura after 10 years of treatment with amlodipine. Antibodies to platelets were tested by standard methods. RESULTS: Initially, the platelet count increased owing to treatment with prednisolone and intravenous immunoglobulin G, but decreased shortly after discontinuation of this treatment. The patient's serum was found to contain amlodipine-dependent antibodies to platelets, and he recovered after stopping the drug. CONCLUSIONS: Amlodipine can induce immune thrombocytopenia, which may strongly resemble autoimmune thrombocytopenia.
BACKGROUND AND OBJECTIVES: Drug-induced thrombocytopenia is a serious, but rare, side-effect of treatment with a number of drugs. In this report, we investigate the suspicion that amlodipine, a calcium-channel blocker, was responsible for immune thrombocytopenia in a 79-year-old patient. PATIENT AND METHODS: Our patient experienced two attacks of thrombocytopenic purpura after 10 years of treatment with amlodipine. Antibodies to platelets were tested by standard methods. RESULTS: Initially, the platelet count increased owing to treatment with prednisolone and intravenous immunoglobulin G, but decreased shortly after discontinuation of this treatment. The patient's serum was found to contain amlodipine-dependent antibodies to platelets, and he recovered after stopping the drug. CONCLUSIONS:Amlodipine can induce immune thrombocytopenia, which may strongly resemble autoimmune thrombocytopenia.