Malignant and Corticosteroid-Dependent Idiopathic Anaphylaxis: Successful Responses to Ketotifen

Malignant idiopathic anaphylaxis refers to the most severe form of idiopathic anaphylaxis where defined episodes of idiopathic anaphylaxis are not controlled when the prednisone is reduced below at least 60 mg every other day or 20 mg daily. Corticosteroid-dependent idiopathic anaphylaxis refers to patients with idiopathic anaphylaxis who require continuous daily or alternate day prednisone at threshold doses for control of idiopathic anaphylaxis. Ketotifen has been reported to help induce remission in some patients with idiopathic anaphylaxis and has steroid sparing effects in other patients with idiopathic anaphylaxis. We present five patients, two with malignant idiopathic anaphylaxis and three with corticosteroid-dependent idiopathic anaphylaxis, who responded to the administration of ketotifen. All five patients, while receiving ketotifen, had a reduction or resolution of their episodes of idiopathic anaphylaxis and prednisone was tapered and discontinued. Ketotifen is shown to be successful in inducing remission in two patients with malignant idiopathic anaphylaxis and in three additional patients with corticosteroid-dependent idiopathic anaphylaxis. An additional patient with malignant idiopathic anaphylaxis had prednisone stopped after elective hip surgery.