Colchicine therapy for refractory idiopathic thrombocytopenic purpura

Fourteen patients with idiopathic thrombocytopenic purpura (ITP) refractory to splenectomy and corticosteroids (prednisone, 1 to 2 mg/kg of body weight per day) received at least 1.2 mg of oral colchicine daily for a minimum of two weeks. Three patients had complete responses and one had a partial response (response rate, 29%). Responses were evident within two weeks of commencing therapy. Only the patient with a partial response was receiving concomitant therapy, a stable dose of prednisone. Responsiveness to colchicine did not seem to correlate with responsiveness to vincristine sulfate. Side effects of colchicine therapy were mild and complications did not occur. A possible mechanism of action for colchicine in ITP is decreased clearance of opsonized platelets secondary to inhibition of microtubule-dependent events in macrophages. Colchicine is useful in the treatment of ITP resistant to standard treatment.