Procainamide-induced pure red cell aplasia

Abstract

Pure red cell aplasia, characterized by severe anemia, reticulocytopenia, and almost complete absence of erythroid precursors but normal granulopoiesis and megakaryocytopoiesis, can be congenital (Diamond-Blackfan anemia) but more typically is acquired, occurring in association with lymphoproliferative disorders, thymomas, solid tumors, autoimmune diseases, and viral infections (parvovirus B19, Epstein–Barr virus, and cytomegalovirus) [1]. Medicament-associated pure red cell aplasia has been linked to selected drugs (phenytoin, azathioprine, and isoniazid) [2]. Procainamide has been considered to be ‘‘possibly’’ associated with acquired pure red cell aplasia. We report a case of pure red cell aplasia caused by procainamide, confirming its causal role in acquired pure red cell aplasia. A 63-year-old man with a metallic aortic valve prosthesis underwent coronary artery bypass and aortic root grafting. Medications included warfarin, lisinopril, prednisone, dipyridamole, diltiazem, and zolpidem tartrate. Cefazolin followed by vancomycin (for 6 weeks) was administered for a postoperative, coagulase-negative staphylococcal infection. Use of diltiazem was discontinued. Use of digoxin and procainamide (750 mg, 4 times daily) was initiated for atrial flutter; procainamide and N-acetylprocainamide levels were within or below the therapeutic range. Within 2 weeks of initiation of procainamide, the patient experienced fevers and ‘‘tea-colored’’ urine. On physical examination he demonstrated pallor, tachypnea, and mechan-