Ezetimibe-associated immune thrombocytopenia

Abstract

Objective: To describe a case of immune thrombocytopenia associated with treatment with ezetimibe, a cholesterol absorption inhibitor.

Case summary: A 72-year-old man presented with severe thrombocytopenia (platelets 3 x 10(3)/muL) and "wet purpura" 4 weeks after being started on daily therapy using a combination of ezetimibe 10 mg/simvastatin 20 mg. Platelet counts normalized after administration of ezetimibe/simvastatin was stopped. Nine months later, the patient was restarted on simvastatin because of uncorrected dyslipidemia. Platelet counts remained within the normal range following that rechallenge.

Discussion: Registry data revealed the possibility of ezetimibe-induced thrombocytopenia, but, as of December 3, 2007, no other case reports on this interaction had been published. This case illustrates the probable occurrence of ezetimibe-induced thrombocytopenia. Platelet counts dropped significantly when ezetimibe therapy was initiated, then resolved upon discontinuation of therapy. Other causes of thrombocytopenia were ruled out, and rechallenge with simvastatin further supports the presence of a causal relationship between thrombocytopenia and ezetimibe. Use of the Naranjo probability scale indicated a probable relationship between thrombocytopenia and ezetimibe therapy. An adverse reaction scale specific for evaluation of drug-induced thrombocytopenia also indicated the probable likelihood of ezetimibe-induced thrombocytopenia. This patient was not rechallenged with ezetimibe due to the highly suggestive timeline present and unnecessary risk for him.

Conclusions: Ezetimibe-associated thrombocytopenia cannot be ruled out in the patient reported here. Clinicians should be aware of this adverse event.