Quinolones and Penicillins Incompatibility

sure, viral hepatitis, tuberculosis, pancreatitis, autoimmune diseases, hematological disorders, or occupational chemical exposure, were present. His aplastic anemia therefore is thought to be secondary to tocainide. The time course of this case is similar to the two previously reported cases of tocainide-induced aplastic anemia. The other patients were noted to have aplastic anemia at 3 months and 75 days after tocainide was begun. One ofthe other patients was alive 110days after the drug was stopped; however, the long-term survival of this patient has not been reported. The other reported patient died from a suspected intracerebral hemorrhage.' No patient who has developed aplastic anemia while taking tocainide has been reported to have had a recovery of their stem cell production upon drug withdrawal. These reports have prompted the manufacturer to change the labeling ofTonocard to emphasize the relatively high rate of serious hematological toxicity and to circulate a "Dear Doctor" letter (personal communication, A. Curtis True, M.D., Merck Sharp & Dohme, November 1987) encouraging practitioners to "limit the use of this drug to patients with life-threatening ventricular arrhythmias or very carefully selected patients with less severe arrhythmias." The manufacturer reports an incidence of serious hematological disorders (agranulocytosis, leukopenia, neutropenia, hypoplastic anem~a, ~nd thrombocytopenia) of 0.18 percent." They recommend monttonng complete blood counts weekly for the first 12 weeks of therapy and periodically thereafter to detect hematological toxicity early. It is unknown, however, whether early detection of hematological depression in patients taking tocainide will prevent the development of aplastic anemia. GREGORY B. MORRILL, Pharm.D. Clinical Pharmacist Veterans Administration Medical Center AssistantClinical Professor ofMedicine SchoolofMedicine University ofNevada Reno. Nevada89520 STEVEN M. GIBSON,M.D. ChiefMedicalResident Veterans AdministrationMedical Center SchoolofMedicine University ofNevada