Drug-induced immune thrombocytopenia.

A variety of drugs and other agents have been reported to cause immune-mediated platelet destruction. The cardinal features of this syndrome are acute, often alarming, purpura, closely related to drug exposure, which remits in one to two weeks after discontinuation of all suspect drugs. Quinidine and quinine have been most commonly implicated but, recently, both heparin and heroin have been the subject of numerous reports. Platelets are removed rapidly from the circulation, apparently as a result of the attachment of drug-antibody immune complexes. In vitro documentation of platelet injury by these complexes has inspired the development of many in vitro tests of differing sophistication. While valuable in confirming the clinical suspicion, none is sufficiently sensitive to exclude the diagnosis.