Acquired hemophilia A is an uncommon but potentially life-threatening hemorrhagic disorder caused by the onset of autoantibodies against coagulation factor VIII. Acquired hemophilia A is most frequently associated with autoimmune diseases, solid tumors, lymphoproliferative diseases, pregnancy, and drug reactions. However, in approximately 50 percent of the patients no underlying disorder can be identified. Prompt diagnosis of this acquired bleeding disorder is essential for appropriate management aimed to control hemorrhage and suppress the inhibitor. Based on electronic and manual searches of the published literature, this review examines the current knowledge on drug-induced factor VIII autoantibodies. A total of 34 cases were identified, mostly related to a variety of agents, including antibiotics and psychiatric and immunomodulatory drugs. In particular there is increased evidence for an association between acquired hemophilia A and interferon given as treatment for hepatitis C virus infection. Although most inhibitors reported in the literature were at high titers (mean: 67.7 Bethesda Units/ml), their prognosis was good, as they disappeared in most cases after suspension of the involved drug or after immunosuppressive therapy (complete remission rate: 83.3%). However, further studies are needed to better elucidate the epidemiology, natural history, clinical relevance, and optimal treatment of drug-associated factor VIII autoantibodies.

Keywords: Antibody Formation - drug effects, Anti-Bacterial Agents - adverse effects, Autoantibodies - immunology, Autoimmune Diseases - immunology, Factor VIII - immunology, Hemophilia A - immunology, Immunologic Factors - adverse effects, Psychotropic Drugs - adverse effects