Ineffectiveness of aspirin and dipyridamole in the treatment of thrombotic thrombocytopenic purpura.

Platelet-inhibiting drugs have been used widely in the treatment of thrombotic thrombocytopenia purpura. Nineteen consecutive patients received various treatments including platelet inhibitors, glucocorticoid drugs, whole blood or plasma exchange transfusions, and splenectomy. During treatment with aspirin and dipyridamole in 14 patients, five died, and only one had neither new neurologic signs nor worsening thrombocytopenia. Prostacyclin in one patient was not beneficial. Serious bleeding complications, including massive upper gastrointestinal hemorrhage, epistaxes, or subarachnoid hemorrhage confirmed at autopsy, occurred in five of the 19 patients and only during treatment with aspirin and dipyridamole. We conclude that there is no evidence for the effectiveness of aspirin and dipyridamole in the treatment of thrombotic thrombocytopenic purpura and that these drugs may increase the risk of serious bleeding complications.