Quinidine-induced immune thrombocytopenia.

We have identified six cases of quinidine-induced immune thrombocytopenia based on clinical evidence and in association with elevated amounts of platelet surface IgG. The degree of thrombocytopenia did not correlate with severity of clinical symptoms, nor did it predict the amount of IgG on the platelet surface. Three of the patients recovered promptly after drug discontinuation alone whereas the other patients received additional corticosteroid therapy. The clinical presentation, mode of diagnosis, and therapeutic considerations in the treatment of drug-induced thrombocytopenia are discussed.