[Diaminodiphenyl sulfone therapy for refractory idiopathic thrombocytopenic purpura--long-term effectiveness and possible mechanisms].

Eight patients with idiopathic thrombocytopenic purpura (ITP) refractory to corticosteroids were given oral diaminodiphenyl sulfone (DDS) (75 mg to 150 mg/day). Responses to DDS were observed in 5 patients, and their platelet counts significantly increased to more than 10 x 10(4)/microliter. The duration of treatment required to obtain platelet counts of more than 10 x 10(4)/microliter ranged from 35 to 64 days. In 3 of the 5 responsive patients, platelet counts stabilized at over 10 x 10(4)/microliter during DDS therapy for 3 to 6 years. Although adverse effects including local skin rash and itching were observed in 3 patients, they disappeared after suspension of DDS or in response to medication with antihistamines. Although the exact mechanism by which it increases the platelet counts in ITP patients is still obscure, DDS may inhibit the reticuloendothelial system by excessive red blood cell destruction. We concluded that DDS therapy is well-tolerated and seems to be an effective alternative treatment for patients with ITP that is refractory to other conventional therapies.