Immune thrombocytopenia associated with hemorrhagic diathesis due to ibuprofen administration.

Acute thrombocytopenic purpura temporally related to the oral administration of ibuprofen developed in a patient with ankylosing spondylitis. Clinical manifestations, with sudden onset occurring within 12 h of drug ingestion and rapid increase of platelet counts following discontinuation of the drug, were characteristic of an antibody-mediated immune pathomechanism. Immunological studies demonstrated IgM and IgG antibodies in the patient's serum that were capable of binding to allogenic platelets in the presence of a metabolite preparation. This finding suggested that an ibuprofen metabolite, rather then the drug itself, was the antigenic agent responsible for the immune reaction. Despite its widespread therapeutic use, ibuprofen has not been described previously as causing immune-mediated thrombocytopenia.