Acquired platelet dysfunction following mithramycin therapy.

The administration of mithramycin to patients with testicular tumors has been accompanied by a hemorrhagic diasthesis, often in the absence of thrombocytopenia. Bleeding time, platelet aggregation, platelet adenine nucleotide levels, and coagulation factor assays were studied in three patients receiving mithramycin for embryonal testicular carcinomas. These studies demonstrated a drug dependent, reversible hemorrhagic diathesis associated with (1) prolongation of bleeding time, (2) decreased platelet aggregation responses to ADP, collagen, and epinephrine, and (3) depleted platelet stores of ADP in the absence of thrombocytopenia. These abnormalities were temporally correlated with the onset of mucocutaneous bleeding in all patients.